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llvm-project/lld/test/ELF/ppc64-tls-missing-gdld.s

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[LLD][PowerPC] Add check in LLD to produce an error for missing TLSGD/TLSLD The function `__tls_get_addr` is used to get the address of an object that is Thread Local Storage. It needs to have two relocations on it. One relocation is for the function call itself and it is either R_PPC64_REL24 or R_PPC64_REL24_NOTOC. The other is R_PPC64_TLSGD or R_PPC64_TLSLD for the symbol that is having its address computed. In the early days of the transition from the ELFv1 ABI that is used for big endian PowerPC Linux distributions to the ELFv2 ABI that is used for little endian PowerPC Linux distributions, there was some ambiguity in the specification of the relocations for TLS. The GNU linker has implemented support for correct handling of calls to __tls_get_addr with a missing relocation. Unfortunately, we didn't notice that the IBM XL compiler did not handle TLS according to the updated ABI until we tried linking XL compiled libraries with LLD. As a result, there is a lot of code out there in various libraries compiled with XL that have this problem. This patch adds a new error check in LLD that makes sure calls to `__tls_get_addr` are not missing the TLSGD/TLSLD relocation. Reviewed By: MaskRay Differential Revision: https://reviews.llvm.org/D85994
2020-08-20 19:02:34 +08:00
# REQUIRES: ppc
[ELF][PPC64] Detect missing R_PPC64_TLSGD/R_PPC64_TLSLD and disable TLS relaxation Alternative to D91611. The TLS General Dynamic/Local Dynamic code sequences need to mark `__tls_get_addr` with R_PPC64_TLSGD or R_PPC64_TLSLD, e.g. ``` addis r3, r2, x@got@tlsgd@ha # R_PPC64_GOT_TLSGD16_HA addi r3, r3, x@got@tlsgd@l # R_PPC64_GOT_TLSGD16_LO bl __tls_get_addr(x@tlsgd) # R_PPC64_TLSGD followed by R_PPC64_REL24 nop ``` However, there are two deviations form the above: 1. direct call to `__tls_get_addr`. This is essential to implement ld.so in glibc/musl/FreeBSD. ``` bl __tls_get_addr nop ``` This is only used in a -shared link, and thus not subject to the GD/LD to IE/LE relaxation issue below. 2. Missing R_PPC64_TLSGD/R_PPC64_TLSGD for compiler generated TLS references According to Stefan Pintille, "In the early days of the transition from the ELFv1 ABI that is used for big endian PowerPC Linux distributions to the ELFv2 ABI that is used for little endian PowerPC Linux distributions, there was some ambiguity in the specification of the relocations for TLS. The GNU linker has implemented support for correct handling of calls to __tls_get_addr with a missing relocation. Unfortunately, we didn't notice that the IBM XL compiler did not handle TLS according to the updated ABI until we tried linking XL compiled libraries with LLD." In short, LLD needs to work around the old IBM XL compiler issue. Otherwise, if the object file is linked in -no-pie or -pie mode, the result will be incorrect because the 4 instructions are partially rewritten (the latter 2 are not changed). Work around the compiler bug by disable General Dynamic/Local Dynamic to Initial Exec/Local Exec relaxation. Note, we also disable Initial Exec to Local Exec relaxation for implementation simplicity, though technically it can be kept. ppc64-tls-missing-gdld.s demonstrates the updated behavior. Reviewed By: #powerpc, stefanp, grimar Differential Revision: https://reviews.llvm.org/D92959
2020-12-22 00:45:41 +08:00
# RUN: split-file %s %t
# RUN: llvm-mc --triple=ppc64le %t/a.s --filetype=obj -o %t/a.o
# RUN: llvm-mc --triple=ppc64le %t/b.s --filetype=obj -o %t/b.o
# RUN: llvm-mc --triple=ppc64le %t/tga.s --filetype=obj -o %t/tga.o
[LLD][PowerPC] Add check in LLD to produce an error for missing TLSGD/TLSLD The function `__tls_get_addr` is used to get the address of an object that is Thread Local Storage. It needs to have two relocations on it. One relocation is for the function call itself and it is either R_PPC64_REL24 or R_PPC64_REL24_NOTOC. The other is R_PPC64_TLSGD or R_PPC64_TLSLD for the symbol that is having its address computed. In the early days of the transition from the ELFv1 ABI that is used for big endian PowerPC Linux distributions to the ELFv2 ABI that is used for little endian PowerPC Linux distributions, there was some ambiguity in the specification of the relocations for TLS. The GNU linker has implemented support for correct handling of calls to __tls_get_addr with a missing relocation. Unfortunately, we didn't notice that the IBM XL compiler did not handle TLS according to the updated ABI until we tried linking XL compiled libraries with LLD. As a result, there is a lot of code out there in various libraries compiled with XL that have this problem. This patch adds a new error check in LLD that makes sure calls to `__tls_get_addr` are not missing the TLSGD/TLSLD relocation. Reviewed By: MaskRay Differential Revision: https://reviews.llvm.org/D85994
2020-08-20 19:02:34 +08:00
[ELF] Don't error on R_PPC64_REL24/R_PPC64_REL24_NOTOC referencing __tls_get_addr for missing R_PPC64_TLSGD/R_PPC64_TLSLD This partially reverts D85994. In glibc, elf/dl-sym.c calls the raw `__tls_get_addr` by specifying the tls_index parameter. Such a call does not have a pairing R_PPC64_TLSGD/R_PPC64_TLSLD. This is legitimate. Since we cannot distinguish the benign case from cases due to toolchain issues, we have to be permissive. Acked by Stefan Pintilie
2020-10-24 01:37:24 +08:00
## User code can call __tls_get_addr by specifying the tls_index parameter.
## We need to allow R_PPC64_REL24/R_PPC64_REL24_NOTOC referencing __tls_get_addr
## without a pairing R_PPC64_TLSGD/R_PPC64_TLSLD.
[ELF][PPC64] Detect missing R_PPC64_TLSGD/R_PPC64_TLSLD and disable TLS relaxation Alternative to D91611. The TLS General Dynamic/Local Dynamic code sequences need to mark `__tls_get_addr` with R_PPC64_TLSGD or R_PPC64_TLSLD, e.g. ``` addis r3, r2, x@got@tlsgd@ha # R_PPC64_GOT_TLSGD16_HA addi r3, r3, x@got@tlsgd@l # R_PPC64_GOT_TLSGD16_LO bl __tls_get_addr(x@tlsgd) # R_PPC64_TLSGD followed by R_PPC64_REL24 nop ``` However, there are two deviations form the above: 1. direct call to `__tls_get_addr`. This is essential to implement ld.so in glibc/musl/FreeBSD. ``` bl __tls_get_addr nop ``` This is only used in a -shared link, and thus not subject to the GD/LD to IE/LE relaxation issue below. 2. Missing R_PPC64_TLSGD/R_PPC64_TLSGD for compiler generated TLS references According to Stefan Pintille, "In the early days of the transition from the ELFv1 ABI that is used for big endian PowerPC Linux distributions to the ELFv2 ABI that is used for little endian PowerPC Linux distributions, there was some ambiguity in the specification of the relocations for TLS. The GNU linker has implemented support for correct handling of calls to __tls_get_addr with a missing relocation. Unfortunately, we didn't notice that the IBM XL compiler did not handle TLS according to the updated ABI until we tried linking XL compiled libraries with LLD." In short, LLD needs to work around the old IBM XL compiler issue. Otherwise, if the object file is linked in -no-pie or -pie mode, the result will be incorrect because the 4 instructions are partially rewritten (the latter 2 are not changed). Work around the compiler bug by disable General Dynamic/Local Dynamic to Initial Exec/Local Exec relaxation. Note, we also disable Initial Exec to Local Exec relaxation for implementation simplicity, though technically it can be kept. ppc64-tls-missing-gdld.s demonstrates the updated behavior. Reviewed By: #powerpc, stefanp, grimar Differential Revision: https://reviews.llvm.org/D92959
2020-12-22 00:45:41 +08:00
# RUN: ld.lld --shared --fatal-warnings %t/b.o -o /dev/null
[LLD][PowerPC] Add check in LLD to produce an error for missing TLSGD/TLSLD The function `__tls_get_addr` is used to get the address of an object that is Thread Local Storage. It needs to have two relocations on it. One relocation is for the function call itself and it is either R_PPC64_REL24 or R_PPC64_REL24_NOTOC. The other is R_PPC64_TLSGD or R_PPC64_TLSLD for the symbol that is having its address computed. In the early days of the transition from the ELFv1 ABI that is used for big endian PowerPC Linux distributions to the ELFv2 ABI that is used for little endian PowerPC Linux distributions, there was some ambiguity in the specification of the relocations for TLS. The GNU linker has implemented support for correct handling of calls to __tls_get_addr with a missing relocation. Unfortunately, we didn't notice that the IBM XL compiler did not handle TLS according to the updated ABI until we tried linking XL compiled libraries with LLD. As a result, there is a lot of code out there in various libraries compiled with XL that have this problem. This patch adds a new error check in LLD that makes sure calls to `__tls_get_addr` are not missing the TLSGD/TLSLD relocation. Reviewed By: MaskRay Differential Revision: https://reviews.llvm.org/D85994
2020-08-20 19:02:34 +08:00
[ELF][PPC64] Detect missing R_PPC64_TLSGD/R_PPC64_TLSLD and disable TLS relaxation Alternative to D91611. The TLS General Dynamic/Local Dynamic code sequences need to mark `__tls_get_addr` with R_PPC64_TLSGD or R_PPC64_TLSLD, e.g. ``` addis r3, r2, x@got@tlsgd@ha # R_PPC64_GOT_TLSGD16_HA addi r3, r3, x@got@tlsgd@l # R_PPC64_GOT_TLSGD16_LO bl __tls_get_addr(x@tlsgd) # R_PPC64_TLSGD followed by R_PPC64_REL24 nop ``` However, there are two deviations form the above: 1. direct call to `__tls_get_addr`. This is essential to implement ld.so in glibc/musl/FreeBSD. ``` bl __tls_get_addr nop ``` This is only used in a -shared link, and thus not subject to the GD/LD to IE/LE relaxation issue below. 2. Missing R_PPC64_TLSGD/R_PPC64_TLSGD for compiler generated TLS references According to Stefan Pintille, "In the early days of the transition from the ELFv1 ABI that is used for big endian PowerPC Linux distributions to the ELFv2 ABI that is used for little endian PowerPC Linux distributions, there was some ambiguity in the specification of the relocations for TLS. The GNU linker has implemented support for correct handling of calls to __tls_get_addr with a missing relocation. Unfortunately, we didn't notice that the IBM XL compiler did not handle TLS according to the updated ABI until we tried linking XL compiled libraries with LLD." In short, LLD needs to work around the old IBM XL compiler issue. Otherwise, if the object file is linked in -no-pie or -pie mode, the result will be incorrect because the 4 instructions are partially rewritten (the latter 2 are not changed). Work around the compiler bug by disable General Dynamic/Local Dynamic to Initial Exec/Local Exec relaxation. Note, we also disable Initial Exec to Local Exec relaxation for implementation simplicity, though technically it can be kept. ppc64-tls-missing-gdld.s demonstrates the updated behavior. Reviewed By: #powerpc, stefanp, grimar Differential Revision: https://reviews.llvm.org/D92959
2020-12-22 00:45:41 +08:00
## Warn missing R_PPC64_TLSGD/R_PPC64_TLSLD.
# RUN: ld.lld --shared %t/a.o -o %t.so 2>&1 | FileCheck %s --check-prefix=WARN
# RUN: llvm-objdump -d --no-leading-addr %t.so | FileCheck %s --check-prefix=DIS
# RUN: ld.lld %t/a.o %t/tga.o -o %t2 2>&1 | FileCheck %s --check-prefix=WARN
# RUN: llvm-readelf -x .got %t2 | FileCheck %s --check-prefix=HEX
# RUN: llvm-objdump -d --no-leading-addr %t2 | FileCheck %s --check-prefix=DIS
# WARN: warning: {{.*}}.o: disable TLS relaxation due to R_PPC64_GOT_TLS* relocations without R_PPC64_TLSGD/R_PPC64_TLSLD relocations
## .got+0: x is local - relaxed to LE - its DTPMOD/DTPREL slots are link-time constants.
## DTPMOD is 1. DTPREL is st_value-0x8000 = -0x8000.
## .got+16: DTPMOD/DTPREL for _TLS_MODULE_BASE_ is 1 and 0, respectively.
## .got+32: TPOFFSET for x = st_value-0x7000
# HEX: section '.got':
[PowerPC] Fix issue where binary uses a .got but is missing a .TOC. From the PowerPC ELFv2 ABI section 4.2.3. Global Offset Table. ``` The GOT consists of an 8-byte header that contains the TOC base (the first TOC base when multiple TOCs are present), followed by an array of 8-byte addresses. ``` Due to the introduction of PC Relative code it is now possible to require a GOT without having a .TOC. symbol in the object that is being linked. Since LLD uses the .TOC. symbol to determine whether or not a GOT is required the GOT header is not setup correctly and the 8-byte header is missing. This patch allows the Power PC GOT setup to happen when an element is added to the GOT instead of at the very begining. When this header is added a .TOC. symbol is also added. Reviewed By: MaskRay Differential Revision: https://reviews.llvm.org/D91426
2021-04-05 21:07:16 +08:00
# HEX-NEXT: [[#%x,IGNORE:]] 50820210 00000000 01000000 00000000
# HEX-NEXT: [[#%x,IGNORE:]] 0080ffff ffffffff 01000000 00000000
# HEX-NEXT: [[#%x,IGNORE:]] 00000000 00000000 0090ffff ffffffff
[ELF][PPC64] Detect missing R_PPC64_TLSGD/R_PPC64_TLSLD and disable TLS relaxation Alternative to D91611. The TLS General Dynamic/Local Dynamic code sequences need to mark `__tls_get_addr` with R_PPC64_TLSGD or R_PPC64_TLSLD, e.g. ``` addis r3, r2, x@got@tlsgd@ha # R_PPC64_GOT_TLSGD16_HA addi r3, r3, x@got@tlsgd@l # R_PPC64_GOT_TLSGD16_LO bl __tls_get_addr(x@tlsgd) # R_PPC64_TLSGD followed by R_PPC64_REL24 nop ``` However, there are two deviations form the above: 1. direct call to `__tls_get_addr`. This is essential to implement ld.so in glibc/musl/FreeBSD. ``` bl __tls_get_addr nop ``` This is only used in a -shared link, and thus not subject to the GD/LD to IE/LE relaxation issue below. 2. Missing R_PPC64_TLSGD/R_PPC64_TLSGD for compiler generated TLS references According to Stefan Pintille, "In the early days of the transition from the ELFv1 ABI that is used for big endian PowerPC Linux distributions to the ELFv2 ABI that is used for little endian PowerPC Linux distributions, there was some ambiguity in the specification of the relocations for TLS. The GNU linker has implemented support for correct handling of calls to __tls_get_addr with a missing relocation. Unfortunately, we didn't notice that the IBM XL compiler did not handle TLS according to the updated ABI until we tried linking XL compiled libraries with LLD." In short, LLD needs to work around the old IBM XL compiler issue. Otherwise, if the object file is linked in -no-pie or -pie mode, the result will be incorrect because the 4 instructions are partially rewritten (the latter 2 are not changed). Work around the compiler bug by disable General Dynamic/Local Dynamic to Initial Exec/Local Exec relaxation. Note, we also disable Initial Exec to Local Exec relaxation for implementation simplicity, though technically it can be kept. ppc64-tls-missing-gdld.s demonstrates the updated behavior. Reviewed By: #powerpc, stefanp, grimar Differential Revision: https://reviews.llvm.org/D92959
2020-12-22 00:45:41 +08:00
## .TOC.-32768 = (.got+0x8000)-32768 = .got
# DIS-LABEL: <GeneralDynamic>:
# DIS-NEXT: addis 3, 2, 0
[PowerPC] Fix issue where binary uses a .got but is missing a .TOC. From the PowerPC ELFv2 ABI section 4.2.3. Global Offset Table. ``` The GOT consists of an 8-byte header that contains the TOC base (the first TOC base when multiple TOCs are present), followed by an array of 8-byte addresses. ``` Due to the introduction of PC Relative code it is now possible to require a GOT without having a .TOC. symbol in the object that is being linked. Since LLD uses the .TOC. symbol to determine whether or not a GOT is required the GOT header is not setup correctly and the 8-byte header is missing. This patch allows the Power PC GOT setup to happen when an element is added to the GOT instead of at the very begining. When this header is added a .TOC. symbol is also added. Reviewed By: MaskRay Differential Revision: https://reviews.llvm.org/D91426
2021-04-05 21:07:16 +08:00
# DIS-NEXT: addi 3, 3, -32760
[ELF][PPC64] Detect missing R_PPC64_TLSGD/R_PPC64_TLSLD and disable TLS relaxation Alternative to D91611. The TLS General Dynamic/Local Dynamic code sequences need to mark `__tls_get_addr` with R_PPC64_TLSGD or R_PPC64_TLSLD, e.g. ``` addis r3, r2, x@got@tlsgd@ha # R_PPC64_GOT_TLSGD16_HA addi r3, r3, x@got@tlsgd@l # R_PPC64_GOT_TLSGD16_LO bl __tls_get_addr(x@tlsgd) # R_PPC64_TLSGD followed by R_PPC64_REL24 nop ``` However, there are two deviations form the above: 1. direct call to `__tls_get_addr`. This is essential to implement ld.so in glibc/musl/FreeBSD. ``` bl __tls_get_addr nop ``` This is only used in a -shared link, and thus not subject to the GD/LD to IE/LE relaxation issue below. 2. Missing R_PPC64_TLSGD/R_PPC64_TLSGD for compiler generated TLS references According to Stefan Pintille, "In the early days of the transition from the ELFv1 ABI that is used for big endian PowerPC Linux distributions to the ELFv2 ABI that is used for little endian PowerPC Linux distributions, there was some ambiguity in the specification of the relocations for TLS. The GNU linker has implemented support for correct handling of calls to __tls_get_addr with a missing relocation. Unfortunately, we didn't notice that the IBM XL compiler did not handle TLS according to the updated ABI until we tried linking XL compiled libraries with LLD." In short, LLD needs to work around the old IBM XL compiler issue. Otherwise, if the object file is linked in -no-pie or -pie mode, the result will be incorrect because the 4 instructions are partially rewritten (the latter 2 are not changed). Work around the compiler bug by disable General Dynamic/Local Dynamic to Initial Exec/Local Exec relaxation. Note, we also disable Initial Exec to Local Exec relaxation for implementation simplicity, though technically it can be kept. ppc64-tls-missing-gdld.s demonstrates the updated behavior. Reviewed By: #powerpc, stefanp, grimar Differential Revision: https://reviews.llvm.org/D92959
2020-12-22 00:45:41 +08:00
# DIS-NEXT: bl [[#%x,TGA:]]
# DIS-LABEL: <GeneralDynamic_NOTOC>:
# DIS-NEXT: addis 3, 2, 0
[PowerPC] Fix issue where binary uses a .got but is missing a .TOC. From the PowerPC ELFv2 ABI section 4.2.3. Global Offset Table. ``` The GOT consists of an 8-byte header that contains the TOC base (the first TOC base when multiple TOCs are present), followed by an array of 8-byte addresses. ``` Due to the introduction of PC Relative code it is now possible to require a GOT without having a .TOC. symbol in the object that is being linked. Since LLD uses the .TOC. symbol to determine whether or not a GOT is required the GOT header is not setup correctly and the 8-byte header is missing. This patch allows the Power PC GOT setup to happen when an element is added to the GOT instead of at the very begining. When this header is added a .TOC. symbol is also added. Reviewed By: MaskRay Differential Revision: https://reviews.llvm.org/D91426
2021-04-05 21:07:16 +08:00
# DIS-NEXT: addi 3, 3, -32760
[ELF][PPC64] Detect missing R_PPC64_TLSGD/R_PPC64_TLSLD and disable TLS relaxation Alternative to D91611. The TLS General Dynamic/Local Dynamic code sequences need to mark `__tls_get_addr` with R_PPC64_TLSGD or R_PPC64_TLSLD, e.g. ``` addis r3, r2, x@got@tlsgd@ha # R_PPC64_GOT_TLSGD16_HA addi r3, r3, x@got@tlsgd@l # R_PPC64_GOT_TLSGD16_LO bl __tls_get_addr(x@tlsgd) # R_PPC64_TLSGD followed by R_PPC64_REL24 nop ``` However, there are two deviations form the above: 1. direct call to `__tls_get_addr`. This is essential to implement ld.so in glibc/musl/FreeBSD. ``` bl __tls_get_addr nop ``` This is only used in a -shared link, and thus not subject to the GD/LD to IE/LE relaxation issue below. 2. Missing R_PPC64_TLSGD/R_PPC64_TLSGD for compiler generated TLS references According to Stefan Pintille, "In the early days of the transition from the ELFv1 ABI that is used for big endian PowerPC Linux distributions to the ELFv2 ABI that is used for little endian PowerPC Linux distributions, there was some ambiguity in the specification of the relocations for TLS. The GNU linker has implemented support for correct handling of calls to __tls_get_addr with a missing relocation. Unfortunately, we didn't notice that the IBM XL compiler did not handle TLS according to the updated ABI until we tried linking XL compiled libraries with LLD." In short, LLD needs to work around the old IBM XL compiler issue. Otherwise, if the object file is linked in -no-pie or -pie mode, the result will be incorrect because the 4 instructions are partially rewritten (the latter 2 are not changed). Work around the compiler bug by disable General Dynamic/Local Dynamic to Initial Exec/Local Exec relaxation. Note, we also disable Initial Exec to Local Exec relaxation for implementation simplicity, though technically it can be kept. ppc64-tls-missing-gdld.s demonstrates the updated behavior. Reviewed By: #powerpc, stefanp, grimar Differential Revision: https://reviews.llvm.org/D92959
2020-12-22 00:45:41 +08:00
# DIS-NEXT: bl [[#TGA]]
## LocalDynamic references _TLS_MODULE_BASE_.
## .TOC.-32752 = (.got+0x8000)-32752 = .got+16
# DIS-LABEL: <LocalDynamic>:
# DIS-NEXT: addis 3, 2, 0
[PowerPC] Fix issue where binary uses a .got but is missing a .TOC. From the PowerPC ELFv2 ABI section 4.2.3. Global Offset Table. ``` The GOT consists of an 8-byte header that contains the TOC base (the first TOC base when multiple TOCs are present), followed by an array of 8-byte addresses. ``` Due to the introduction of PC Relative code it is now possible to require a GOT without having a .TOC. symbol in the object that is being linked. Since LLD uses the .TOC. symbol to determine whether or not a GOT is required the GOT header is not setup correctly and the 8-byte header is missing. This patch allows the Power PC GOT setup to happen when an element is added to the GOT instead of at the very begining. When this header is added a .TOC. symbol is also added. Reviewed By: MaskRay Differential Revision: https://reviews.llvm.org/D91426
2021-04-05 21:07:16 +08:00
# DIS-NEXT: addi 3, 3, -32744
[ELF][PPC64] Detect missing R_PPC64_TLSGD/R_PPC64_TLSLD and disable TLS relaxation Alternative to D91611. The TLS General Dynamic/Local Dynamic code sequences need to mark `__tls_get_addr` with R_PPC64_TLSGD or R_PPC64_TLSLD, e.g. ``` addis r3, r2, x@got@tlsgd@ha # R_PPC64_GOT_TLSGD16_HA addi r3, r3, x@got@tlsgd@l # R_PPC64_GOT_TLSGD16_LO bl __tls_get_addr(x@tlsgd) # R_PPC64_TLSGD followed by R_PPC64_REL24 nop ``` However, there are two deviations form the above: 1. direct call to `__tls_get_addr`. This is essential to implement ld.so in glibc/musl/FreeBSD. ``` bl __tls_get_addr nop ``` This is only used in a -shared link, and thus not subject to the GD/LD to IE/LE relaxation issue below. 2. Missing R_PPC64_TLSGD/R_PPC64_TLSGD for compiler generated TLS references According to Stefan Pintille, "In the early days of the transition from the ELFv1 ABI that is used for big endian PowerPC Linux distributions to the ELFv2 ABI that is used for little endian PowerPC Linux distributions, there was some ambiguity in the specification of the relocations for TLS. The GNU linker has implemented support for correct handling of calls to __tls_get_addr with a missing relocation. Unfortunately, we didn't notice that the IBM XL compiler did not handle TLS according to the updated ABI until we tried linking XL compiled libraries with LLD." In short, LLD needs to work around the old IBM XL compiler issue. Otherwise, if the object file is linked in -no-pie or -pie mode, the result will be incorrect because the 4 instructions are partially rewritten (the latter 2 are not changed). Work around the compiler bug by disable General Dynamic/Local Dynamic to Initial Exec/Local Exec relaxation. Note, we also disable Initial Exec to Local Exec relaxation for implementation simplicity, though technically it can be kept. ppc64-tls-missing-gdld.s demonstrates the updated behavior. Reviewed By: #powerpc, stefanp, grimar Differential Revision: https://reviews.llvm.org/D92959
2020-12-22 00:45:41 +08:00
# DIS-NEXT: bl [[#TGA]]
# DIS-LABEL: <LocalDynamic_NOTOC>:
# DIS-NEXT: addis 3, 2, 0
[PowerPC] Fix issue where binary uses a .got but is missing a .TOC. From the PowerPC ELFv2 ABI section 4.2.3. Global Offset Table. ``` The GOT consists of an 8-byte header that contains the TOC base (the first TOC base when multiple TOCs are present), followed by an array of 8-byte addresses. ``` Due to the introduction of PC Relative code it is now possible to require a GOT without having a .TOC. symbol in the object that is being linked. Since LLD uses the .TOC. symbol to determine whether or not a GOT is required the GOT header is not setup correctly and the 8-byte header is missing. This patch allows the Power PC GOT setup to happen when an element is added to the GOT instead of at the very begining. When this header is added a .TOC. symbol is also added. Reviewed By: MaskRay Differential Revision: https://reviews.llvm.org/D91426
2021-04-05 21:07:16 +08:00
# DIS-NEXT: addi 3, 3, -32744
[ELF][PPC64] Detect missing R_PPC64_TLSGD/R_PPC64_TLSLD and disable TLS relaxation Alternative to D91611. The TLS General Dynamic/Local Dynamic code sequences need to mark `__tls_get_addr` with R_PPC64_TLSGD or R_PPC64_TLSLD, e.g. ``` addis r3, r2, x@got@tlsgd@ha # R_PPC64_GOT_TLSGD16_HA addi r3, r3, x@got@tlsgd@l # R_PPC64_GOT_TLSGD16_LO bl __tls_get_addr(x@tlsgd) # R_PPC64_TLSGD followed by R_PPC64_REL24 nop ``` However, there are two deviations form the above: 1. direct call to `__tls_get_addr`. This is essential to implement ld.so in glibc/musl/FreeBSD. ``` bl __tls_get_addr nop ``` This is only used in a -shared link, and thus not subject to the GD/LD to IE/LE relaxation issue below. 2. Missing R_PPC64_TLSGD/R_PPC64_TLSGD for compiler generated TLS references According to Stefan Pintille, "In the early days of the transition from the ELFv1 ABI that is used for big endian PowerPC Linux distributions to the ELFv2 ABI that is used for little endian PowerPC Linux distributions, there was some ambiguity in the specification of the relocations for TLS. The GNU linker has implemented support for correct handling of calls to __tls_get_addr with a missing relocation. Unfortunately, we didn't notice that the IBM XL compiler did not handle TLS according to the updated ABI until we tried linking XL compiled libraries with LLD." In short, LLD needs to work around the old IBM XL compiler issue. Otherwise, if the object file is linked in -no-pie or -pie mode, the result will be incorrect because the 4 instructions are partially rewritten (the latter 2 are not changed). Work around the compiler bug by disable General Dynamic/Local Dynamic to Initial Exec/Local Exec relaxation. Note, we also disable Initial Exec to Local Exec relaxation for implementation simplicity, though technically it can be kept. ppc64-tls-missing-gdld.s demonstrates the updated behavior. Reviewed By: #powerpc, stefanp, grimar Differential Revision: https://reviews.llvm.org/D92959
2020-12-22 00:45:41 +08:00
# DIS-NEXT: bl [[#TGA]]
## Technically we don't have to disable IE to LE relaxation,
## but disabling it for implementation simplicity does not hurt.
# DIS-LABEL: <InitialExec>:
# DIS-NEXT: addis 3, 2, 0
[PowerPC] Fix issue where binary uses a .got but is missing a .TOC. From the PowerPC ELFv2 ABI section 4.2.3. Global Offset Table. ``` The GOT consists of an 8-byte header that contains the TOC base (the first TOC base when multiple TOCs are present), followed by an array of 8-byte addresses. ``` Due to the introduction of PC Relative code it is now possible to require a GOT without having a .TOC. symbol in the object that is being linked. Since LLD uses the .TOC. symbol to determine whether or not a GOT is required the GOT header is not setup correctly and the 8-byte header is missing. This patch allows the Power PC GOT setup to happen when an element is added to the GOT instead of at the very begining. When this header is added a .TOC. symbol is also added. Reviewed By: MaskRay Differential Revision: https://reviews.llvm.org/D91426
2021-04-05 21:07:16 +08:00
# DIS-NEXT: ld 3, -32728(3)
[ELF][PPC64] Detect missing R_PPC64_TLSGD/R_PPC64_TLSLD and disable TLS relaxation Alternative to D91611. The TLS General Dynamic/Local Dynamic code sequences need to mark `__tls_get_addr` with R_PPC64_TLSGD or R_PPC64_TLSLD, e.g. ``` addis r3, r2, x@got@tlsgd@ha # R_PPC64_GOT_TLSGD16_HA addi r3, r3, x@got@tlsgd@l # R_PPC64_GOT_TLSGD16_LO bl __tls_get_addr(x@tlsgd) # R_PPC64_TLSGD followed by R_PPC64_REL24 nop ``` However, there are two deviations form the above: 1. direct call to `__tls_get_addr`. This is essential to implement ld.so in glibc/musl/FreeBSD. ``` bl __tls_get_addr nop ``` This is only used in a -shared link, and thus not subject to the GD/LD to IE/LE relaxation issue below. 2. Missing R_PPC64_TLSGD/R_PPC64_TLSGD for compiler generated TLS references According to Stefan Pintille, "In the early days of the transition from the ELFv1 ABI that is used for big endian PowerPC Linux distributions to the ELFv2 ABI that is used for little endian PowerPC Linux distributions, there was some ambiguity in the specification of the relocations for TLS. The GNU linker has implemented support for correct handling of calls to __tls_get_addr with a missing relocation. Unfortunately, we didn't notice that the IBM XL compiler did not handle TLS according to the updated ABI until we tried linking XL compiled libraries with LLD." In short, LLD needs to work around the old IBM XL compiler issue. Otherwise, if the object file is linked in -no-pie or -pie mode, the result will be incorrect because the 4 instructions are partially rewritten (the latter 2 are not changed). Work around the compiler bug by disable General Dynamic/Local Dynamic to Initial Exec/Local Exec relaxation. Note, we also disable Initial Exec to Local Exec relaxation for implementation simplicity, though technically it can be kept. ppc64-tls-missing-gdld.s demonstrates the updated behavior. Reviewed By: #powerpc, stefanp, grimar Differential Revision: https://reviews.llvm.org/D92959
2020-12-22 00:45:41 +08:00
# DIS-NEXT: add 3, 3, 13
#--- a.s
[LLD][PowerPC] Add check in LLD to produce an error for missing TLSGD/TLSLD The function `__tls_get_addr` is used to get the address of an object that is Thread Local Storage. It needs to have two relocations on it. One relocation is for the function call itself and it is either R_PPC64_REL24 or R_PPC64_REL24_NOTOC. The other is R_PPC64_TLSGD or R_PPC64_TLSLD for the symbol that is having its address computed. In the early days of the transition from the ELFv1 ABI that is used for big endian PowerPC Linux distributions to the ELFv2 ABI that is used for little endian PowerPC Linux distributions, there was some ambiguity in the specification of the relocations for TLS. The GNU linker has implemented support for correct handling of calls to __tls_get_addr with a missing relocation. Unfortunately, we didn't notice that the IBM XL compiler did not handle TLS according to the updated ABI until we tried linking XL compiled libraries with LLD. As a result, there is a lot of code out there in various libraries compiled with XL that have this problem. This patch adds a new error check in LLD that makes sure calls to `__tls_get_addr` are not missing the TLSGD/TLSLD relocation. Reviewed By: MaskRay Differential Revision: https://reviews.llvm.org/D85994
2020-08-20 19:02:34 +08:00
GeneralDynamic:
addis 3, 2, x@got@tlsgd@ha
addi 3, 3, x@got@tlsgd@l
bl __tls_get_addr
[ELF][PPC64] Detect missing R_PPC64_TLSGD/R_PPC64_TLSLD and disable TLS relaxation Alternative to D91611. The TLS General Dynamic/Local Dynamic code sequences need to mark `__tls_get_addr` with R_PPC64_TLSGD or R_PPC64_TLSLD, e.g. ``` addis r3, r2, x@got@tlsgd@ha # R_PPC64_GOT_TLSGD16_HA addi r3, r3, x@got@tlsgd@l # R_PPC64_GOT_TLSGD16_LO bl __tls_get_addr(x@tlsgd) # R_PPC64_TLSGD followed by R_PPC64_REL24 nop ``` However, there are two deviations form the above: 1. direct call to `__tls_get_addr`. This is essential to implement ld.so in glibc/musl/FreeBSD. ``` bl __tls_get_addr nop ``` This is only used in a -shared link, and thus not subject to the GD/LD to IE/LE relaxation issue below. 2. Missing R_PPC64_TLSGD/R_PPC64_TLSGD for compiler generated TLS references According to Stefan Pintille, "In the early days of the transition from the ELFv1 ABI that is used for big endian PowerPC Linux distributions to the ELFv2 ABI that is used for little endian PowerPC Linux distributions, there was some ambiguity in the specification of the relocations for TLS. The GNU linker has implemented support for correct handling of calls to __tls_get_addr with a missing relocation. Unfortunately, we didn't notice that the IBM XL compiler did not handle TLS according to the updated ABI until we tried linking XL compiled libraries with LLD." In short, LLD needs to work around the old IBM XL compiler issue. Otherwise, if the object file is linked in -no-pie or -pie mode, the result will be incorrect because the 4 instructions are partially rewritten (the latter 2 are not changed). Work around the compiler bug by disable General Dynamic/Local Dynamic to Initial Exec/Local Exec relaxation. Note, we also disable Initial Exec to Local Exec relaxation for implementation simplicity, though technically it can be kept. ppc64-tls-missing-gdld.s demonstrates the updated behavior. Reviewed By: #powerpc, stefanp, grimar Differential Revision: https://reviews.llvm.org/D92959
2020-12-22 00:45:41 +08:00
nop
[LLD][PowerPC] Add check in LLD to produce an error for missing TLSGD/TLSLD The function `__tls_get_addr` is used to get the address of an object that is Thread Local Storage. It needs to have two relocations on it. One relocation is for the function call itself and it is either R_PPC64_REL24 or R_PPC64_REL24_NOTOC. The other is R_PPC64_TLSGD or R_PPC64_TLSLD for the symbol that is having its address computed. In the early days of the transition from the ELFv1 ABI that is used for big endian PowerPC Linux distributions to the ELFv2 ABI that is used for little endian PowerPC Linux distributions, there was some ambiguity in the specification of the relocations for TLS. The GNU linker has implemented support for correct handling of calls to __tls_get_addr with a missing relocation. Unfortunately, we didn't notice that the IBM XL compiler did not handle TLS according to the updated ABI until we tried linking XL compiled libraries with LLD. As a result, there is a lot of code out there in various libraries compiled with XL that have this problem. This patch adds a new error check in LLD that makes sure calls to `__tls_get_addr` are not missing the TLSGD/TLSLD relocation. Reviewed By: MaskRay Differential Revision: https://reviews.llvm.org/D85994
2020-08-20 19:02:34 +08:00
GeneralDynamic_NOTOC:
addis 3, 2, x@got@tlsgd@ha
addi 3, 3, x@got@tlsgd@l
bl __tls_get_addr@notoc
[ELF][PPC64] Detect missing R_PPC64_TLSGD/R_PPC64_TLSLD and disable TLS relaxation Alternative to D91611. The TLS General Dynamic/Local Dynamic code sequences need to mark `__tls_get_addr` with R_PPC64_TLSGD or R_PPC64_TLSLD, e.g. ``` addis r3, r2, x@got@tlsgd@ha # R_PPC64_GOT_TLSGD16_HA addi r3, r3, x@got@tlsgd@l # R_PPC64_GOT_TLSGD16_LO bl __tls_get_addr(x@tlsgd) # R_PPC64_TLSGD followed by R_PPC64_REL24 nop ``` However, there are two deviations form the above: 1. direct call to `__tls_get_addr`. This is essential to implement ld.so in glibc/musl/FreeBSD. ``` bl __tls_get_addr nop ``` This is only used in a -shared link, and thus not subject to the GD/LD to IE/LE relaxation issue below. 2. Missing R_PPC64_TLSGD/R_PPC64_TLSGD for compiler generated TLS references According to Stefan Pintille, "In the early days of the transition from the ELFv1 ABI that is used for big endian PowerPC Linux distributions to the ELFv2 ABI that is used for little endian PowerPC Linux distributions, there was some ambiguity in the specification of the relocations for TLS. The GNU linker has implemented support for correct handling of calls to __tls_get_addr with a missing relocation. Unfortunately, we didn't notice that the IBM XL compiler did not handle TLS according to the updated ABI until we tried linking XL compiled libraries with LLD." In short, LLD needs to work around the old IBM XL compiler issue. Otherwise, if the object file is linked in -no-pie or -pie mode, the result will be incorrect because the 4 instructions are partially rewritten (the latter 2 are not changed). Work around the compiler bug by disable General Dynamic/Local Dynamic to Initial Exec/Local Exec relaxation. Note, we also disable Initial Exec to Local Exec relaxation for implementation simplicity, though technically it can be kept. ppc64-tls-missing-gdld.s demonstrates the updated behavior. Reviewed By: #powerpc, stefanp, grimar Differential Revision: https://reviews.llvm.org/D92959
2020-12-22 00:45:41 +08:00
nop
[LLD][PowerPC] Add check in LLD to produce an error for missing TLSGD/TLSLD The function `__tls_get_addr` is used to get the address of an object that is Thread Local Storage. It needs to have two relocations on it. One relocation is for the function call itself and it is either R_PPC64_REL24 or R_PPC64_REL24_NOTOC. The other is R_PPC64_TLSGD or R_PPC64_TLSLD for the symbol that is having its address computed. In the early days of the transition from the ELFv1 ABI that is used for big endian PowerPC Linux distributions to the ELFv2 ABI that is used for little endian PowerPC Linux distributions, there was some ambiguity in the specification of the relocations for TLS. The GNU linker has implemented support for correct handling of calls to __tls_get_addr with a missing relocation. Unfortunately, we didn't notice that the IBM XL compiler did not handle TLS according to the updated ABI until we tried linking XL compiled libraries with LLD. As a result, there is a lot of code out there in various libraries compiled with XL that have this problem. This patch adds a new error check in LLD that makes sure calls to `__tls_get_addr` are not missing the TLSGD/TLSLD relocation. Reviewed By: MaskRay Differential Revision: https://reviews.llvm.org/D85994
2020-08-20 19:02:34 +08:00
LocalDynamic:
addis 3, 2, x@got@tlsld@ha
addi 3, 3, x@got@tlsld@l
bl __tls_get_addr
[ELF][PPC64] Detect missing R_PPC64_TLSGD/R_PPC64_TLSLD and disable TLS relaxation Alternative to D91611. The TLS General Dynamic/Local Dynamic code sequences need to mark `__tls_get_addr` with R_PPC64_TLSGD or R_PPC64_TLSLD, e.g. ``` addis r3, r2, x@got@tlsgd@ha # R_PPC64_GOT_TLSGD16_HA addi r3, r3, x@got@tlsgd@l # R_PPC64_GOT_TLSGD16_LO bl __tls_get_addr(x@tlsgd) # R_PPC64_TLSGD followed by R_PPC64_REL24 nop ``` However, there are two deviations form the above: 1. direct call to `__tls_get_addr`. This is essential to implement ld.so in glibc/musl/FreeBSD. ``` bl __tls_get_addr nop ``` This is only used in a -shared link, and thus not subject to the GD/LD to IE/LE relaxation issue below. 2. Missing R_PPC64_TLSGD/R_PPC64_TLSGD for compiler generated TLS references According to Stefan Pintille, "In the early days of the transition from the ELFv1 ABI that is used for big endian PowerPC Linux distributions to the ELFv2 ABI that is used for little endian PowerPC Linux distributions, there was some ambiguity in the specification of the relocations for TLS. The GNU linker has implemented support for correct handling of calls to __tls_get_addr with a missing relocation. Unfortunately, we didn't notice that the IBM XL compiler did not handle TLS according to the updated ABI until we tried linking XL compiled libraries with LLD." In short, LLD needs to work around the old IBM XL compiler issue. Otherwise, if the object file is linked in -no-pie or -pie mode, the result will be incorrect because the 4 instructions are partially rewritten (the latter 2 are not changed). Work around the compiler bug by disable General Dynamic/Local Dynamic to Initial Exec/Local Exec relaxation. Note, we also disable Initial Exec to Local Exec relaxation for implementation simplicity, though technically it can be kept. ppc64-tls-missing-gdld.s demonstrates the updated behavior. Reviewed By: #powerpc, stefanp, grimar Differential Revision: https://reviews.llvm.org/D92959
2020-12-22 00:45:41 +08:00
nop
[LLD][PowerPC] Add check in LLD to produce an error for missing TLSGD/TLSLD The function `__tls_get_addr` is used to get the address of an object that is Thread Local Storage. It needs to have two relocations on it. One relocation is for the function call itself and it is either R_PPC64_REL24 or R_PPC64_REL24_NOTOC. The other is R_PPC64_TLSGD or R_PPC64_TLSLD for the symbol that is having its address computed. In the early days of the transition from the ELFv1 ABI that is used for big endian PowerPC Linux distributions to the ELFv2 ABI that is used for little endian PowerPC Linux distributions, there was some ambiguity in the specification of the relocations for TLS. The GNU linker has implemented support for correct handling of calls to __tls_get_addr with a missing relocation. Unfortunately, we didn't notice that the IBM XL compiler did not handle TLS according to the updated ABI until we tried linking XL compiled libraries with LLD. As a result, there is a lot of code out there in various libraries compiled with XL that have this problem. This patch adds a new error check in LLD that makes sure calls to `__tls_get_addr` are not missing the TLSGD/TLSLD relocation. Reviewed By: MaskRay Differential Revision: https://reviews.llvm.org/D85994
2020-08-20 19:02:34 +08:00
LocalDynamic_NOTOC:
addis 3, 2, x@got@tlsld@ha
addi 3, 3, x@got@tlsld@l
bl __tls_get_addr@notoc
[ELF][PPC64] Detect missing R_PPC64_TLSGD/R_PPC64_TLSLD and disable TLS relaxation Alternative to D91611. The TLS General Dynamic/Local Dynamic code sequences need to mark `__tls_get_addr` with R_PPC64_TLSGD or R_PPC64_TLSLD, e.g. ``` addis r3, r2, x@got@tlsgd@ha # R_PPC64_GOT_TLSGD16_HA addi r3, r3, x@got@tlsgd@l # R_PPC64_GOT_TLSGD16_LO bl __tls_get_addr(x@tlsgd) # R_PPC64_TLSGD followed by R_PPC64_REL24 nop ``` However, there are two deviations form the above: 1. direct call to `__tls_get_addr`. This is essential to implement ld.so in glibc/musl/FreeBSD. ``` bl __tls_get_addr nop ``` This is only used in a -shared link, and thus not subject to the GD/LD to IE/LE relaxation issue below. 2. Missing R_PPC64_TLSGD/R_PPC64_TLSGD for compiler generated TLS references According to Stefan Pintille, "In the early days of the transition from the ELFv1 ABI that is used for big endian PowerPC Linux distributions to the ELFv2 ABI that is used for little endian PowerPC Linux distributions, there was some ambiguity in the specification of the relocations for TLS. The GNU linker has implemented support for correct handling of calls to __tls_get_addr with a missing relocation. Unfortunately, we didn't notice that the IBM XL compiler did not handle TLS according to the updated ABI until we tried linking XL compiled libraries with LLD." In short, LLD needs to work around the old IBM XL compiler issue. Otherwise, if the object file is linked in -no-pie or -pie mode, the result will be incorrect because the 4 instructions are partially rewritten (the latter 2 are not changed). Work around the compiler bug by disable General Dynamic/Local Dynamic to Initial Exec/Local Exec relaxation. Note, we also disable Initial Exec to Local Exec relaxation for implementation simplicity, though technically it can be kept. ppc64-tls-missing-gdld.s demonstrates the updated behavior. Reviewed By: #powerpc, stefanp, grimar Differential Revision: https://reviews.llvm.org/D92959
2020-12-22 00:45:41 +08:00
nop
InitialExec:
addis 3, 2, x@got@tprel@ha
ld 3, x@got@tprel@l(3)
add 3, 3, x@tls
[LLD][PowerPC] Add check in LLD to produce an error for missing TLSGD/TLSLD The function `__tls_get_addr` is used to get the address of an object that is Thread Local Storage. It needs to have two relocations on it. One relocation is for the function call itself and it is either R_PPC64_REL24 or R_PPC64_REL24_NOTOC. The other is R_PPC64_TLSGD or R_PPC64_TLSLD for the symbol that is having its address computed. In the early days of the transition from the ELFv1 ABI that is used for big endian PowerPC Linux distributions to the ELFv2 ABI that is used for little endian PowerPC Linux distributions, there was some ambiguity in the specification of the relocations for TLS. The GNU linker has implemented support for correct handling of calls to __tls_get_addr with a missing relocation. Unfortunately, we didn't notice that the IBM XL compiler did not handle TLS according to the updated ABI until we tried linking XL compiled libraries with LLD. As a result, there is a lot of code out there in various libraries compiled with XL that have this problem. This patch adds a new error check in LLD that makes sure calls to `__tls_get_addr` are not missing the TLSGD/TLSLD relocation. Reviewed By: MaskRay Differential Revision: https://reviews.llvm.org/D85994
2020-08-20 19:02:34 +08:00
[ELF][PPC64] Detect missing R_PPC64_TLSGD/R_PPC64_TLSLD and disable TLS relaxation Alternative to D91611. The TLS General Dynamic/Local Dynamic code sequences need to mark `__tls_get_addr` with R_PPC64_TLSGD or R_PPC64_TLSLD, e.g. ``` addis r3, r2, x@got@tlsgd@ha # R_PPC64_GOT_TLSGD16_HA addi r3, r3, x@got@tlsgd@l # R_PPC64_GOT_TLSGD16_LO bl __tls_get_addr(x@tlsgd) # R_PPC64_TLSGD followed by R_PPC64_REL24 nop ``` However, there are two deviations form the above: 1. direct call to `__tls_get_addr`. This is essential to implement ld.so in glibc/musl/FreeBSD. ``` bl __tls_get_addr nop ``` This is only used in a -shared link, and thus not subject to the GD/LD to IE/LE relaxation issue below. 2. Missing R_PPC64_TLSGD/R_PPC64_TLSGD for compiler generated TLS references According to Stefan Pintille, "In the early days of the transition from the ELFv1 ABI that is used for big endian PowerPC Linux distributions to the ELFv2 ABI that is used for little endian PowerPC Linux distributions, there was some ambiguity in the specification of the relocations for TLS. The GNU linker has implemented support for correct handling of calls to __tls_get_addr with a missing relocation. Unfortunately, we didn't notice that the IBM XL compiler did not handle TLS according to the updated ABI until we tried linking XL compiled libraries with LLD." In short, LLD needs to work around the old IBM XL compiler issue. Otherwise, if the object file is linked in -no-pie or -pie mode, the result will be incorrect because the 4 instructions are partially rewritten (the latter 2 are not changed). Work around the compiler bug by disable General Dynamic/Local Dynamic to Initial Exec/Local Exec relaxation. Note, we also disable Initial Exec to Local Exec relaxation for implementation simplicity, though technically it can be kept. ppc64-tls-missing-gdld.s demonstrates the updated behavior. Reviewed By: #powerpc, stefanp, grimar Differential Revision: https://reviews.llvm.org/D92959
2020-12-22 00:45:41 +08:00
.globl _start
_start:
.section .tbss,"awT",@nobits
.globl x
x:
.quad 0
#--- b.s
[LLD][PowerPC] Add check in LLD to produce an error for missing TLSGD/TLSLD The function `__tls_get_addr` is used to get the address of an object that is Thread Local Storage. It needs to have two relocations on it. One relocation is for the function call itself and it is either R_PPC64_REL24 or R_PPC64_REL24_NOTOC. The other is R_PPC64_TLSGD or R_PPC64_TLSLD for the symbol that is having its address computed. In the early days of the transition from the ELFv1 ABI that is used for big endian PowerPC Linux distributions to the ELFv2 ABI that is used for little endian PowerPC Linux distributions, there was some ambiguity in the specification of the relocations for TLS. The GNU linker has implemented support for correct handling of calls to __tls_get_addr with a missing relocation. Unfortunately, we didn't notice that the IBM XL compiler did not handle TLS according to the updated ABI until we tried linking XL compiled libraries with LLD. As a result, there is a lot of code out there in various libraries compiled with XL that have this problem. This patch adds a new error check in LLD that makes sure calls to `__tls_get_addr` are not missing the TLSGD/TLSLD relocation. Reviewed By: MaskRay Differential Revision: https://reviews.llvm.org/D85994
2020-08-20 19:02:34 +08:00
CallOnly:
bl __tls_get_addr
[ELF][PPC64] Detect missing R_PPC64_TLSGD/R_PPC64_TLSLD and disable TLS relaxation Alternative to D91611. The TLS General Dynamic/Local Dynamic code sequences need to mark `__tls_get_addr` with R_PPC64_TLSGD or R_PPC64_TLSLD, e.g. ``` addis r3, r2, x@got@tlsgd@ha # R_PPC64_GOT_TLSGD16_HA addi r3, r3, x@got@tlsgd@l # R_PPC64_GOT_TLSGD16_LO bl __tls_get_addr(x@tlsgd) # R_PPC64_TLSGD followed by R_PPC64_REL24 nop ``` However, there are two deviations form the above: 1. direct call to `__tls_get_addr`. This is essential to implement ld.so in glibc/musl/FreeBSD. ``` bl __tls_get_addr nop ``` This is only used in a -shared link, and thus not subject to the GD/LD to IE/LE relaxation issue below. 2. Missing R_PPC64_TLSGD/R_PPC64_TLSGD for compiler generated TLS references According to Stefan Pintille, "In the early days of the transition from the ELFv1 ABI that is used for big endian PowerPC Linux distributions to the ELFv2 ABI that is used for little endian PowerPC Linux distributions, there was some ambiguity in the specification of the relocations for TLS. The GNU linker has implemented support for correct handling of calls to __tls_get_addr with a missing relocation. Unfortunately, we didn't notice that the IBM XL compiler did not handle TLS according to the updated ABI until we tried linking XL compiled libraries with LLD." In short, LLD needs to work around the old IBM XL compiler issue. Otherwise, if the object file is linked in -no-pie or -pie mode, the result will be incorrect because the 4 instructions are partially rewritten (the latter 2 are not changed). Work around the compiler bug by disable General Dynamic/Local Dynamic to Initial Exec/Local Exec relaxation. Note, we also disable Initial Exec to Local Exec relaxation for implementation simplicity, though technically it can be kept. ppc64-tls-missing-gdld.s demonstrates the updated behavior. Reviewed By: #powerpc, stefanp, grimar Differential Revision: https://reviews.llvm.org/D92959
2020-12-22 00:45:41 +08:00
nop
blr
#--- tga.s
.globl __tls_get_addr
__tls_get_addr:
[LLD][PowerPC] Add check in LLD to produce an error for missing TLSGD/TLSLD The function `__tls_get_addr` is used to get the address of an object that is Thread Local Storage. It needs to have two relocations on it. One relocation is for the function call itself and it is either R_PPC64_REL24 or R_PPC64_REL24_NOTOC. The other is R_PPC64_TLSGD or R_PPC64_TLSLD for the symbol that is having its address computed. In the early days of the transition from the ELFv1 ABI that is used for big endian PowerPC Linux distributions to the ELFv2 ABI that is used for little endian PowerPC Linux distributions, there was some ambiguity in the specification of the relocations for TLS. The GNU linker has implemented support for correct handling of calls to __tls_get_addr with a missing relocation. Unfortunately, we didn't notice that the IBM XL compiler did not handle TLS according to the updated ABI until we tried linking XL compiled libraries with LLD. As a result, there is a lot of code out there in various libraries compiled with XL that have this problem. This patch adds a new error check in LLD that makes sure calls to `__tls_get_addr` are not missing the TLSGD/TLSLD relocation. Reviewed By: MaskRay Differential Revision: https://reviews.llvm.org/D85994
2020-08-20 19:02:34 +08:00
blr