2018-05-26 02:26:14 +08:00
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// REQUIRES: x86
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// RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %p/Inputs/shared.s -o %t1.o
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// RUN: ld.lld -o %t.so -shared %t1.o
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// RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t2.o
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2018-05-26 05:14:45 +08:00
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// RUN: ld.lld -o %t1.exe %t2.o %t.so -image-base=0xcafe00000000
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// RUN: llvm-objdump -s -j .got.plt %t1.exe | FileCheck %s
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2018-05-26 02:26:14 +08:00
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// CHECK: Contents of section .got.plt:
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[ELF] Simplify RelRo, TLS, NOBITS section ranks and make RW PT_LOAD start with RelRo
Old: PT_LOAD(.data | PT_GNU_RELRO(.data.rel.ro .bss.rel.ro) | .bss)
New: PT_LOAD(PT_GNU_RELRO(.data.rel.ro .bss.rel.ro) | .data .bss)
The placement of | indicates page alignment caused by PT_GNU_RELRO. The
new layout has simpler rules and saves space for many cases.
Old size: roundup(.data) + roundup(.data.rel.ro)
New size: roundup(.data.rel.ro + .bss.rel.ro) + .data
Other advantages:
* At runtime the 3 memory mappings decrease to 2.
* start(PT_TLS) = start(PT_GNU_RELRO) = start(RW PT_LOAD). This
simplifies binary manipulation tools.
GNU strip before 2.31 discards PT_GNU_RELRO if its
address is not equal to the start of its associated PT_LOAD.
This has been fixed by https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=f2731e0c374e5323ce4cdae2bcc7b7fe22da1a6f
But with this change, we will be compatible with GNU strip before 2.31
* Before, .got.plt (non-relro by default) was placed before .got (relro
by default), which made it impossible to have _GLOBAL_OFFSET_TABLE_
(start of .got.plt on x86-64) equal to the end of .got (R_GOT*_FROM_END)
(https://bugs.llvm.org/show_bug.cgi?id=36555). With the new ordering, we
can improve on this regard if we'd like to.
Reviewers: ruiu, espindola, pcc
Subscribers: emaste, arichardson, llvm-commits, joerg, jdoerfert
Differential Revision: https://reviews.llvm.org/D56828
llvm-svn: 356117
2019-03-14 11:47:45 +08:00
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// CHECK-NEXT: cafe00003000 00200000 feca0000 00000000 00000000
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// CHECK-NEXT: cafe00003010 00000000 00000000 26100000 feca0000
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2018-05-26 02:26:14 +08:00
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2018-05-26 05:14:45 +08:00
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// RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t2.o
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// RUN: ld.lld -o %t2.exe %t2.o %t.so -image-base=0xcafe00000000 -z retpolineplt
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// RUN: llvm-objdump -s -j .got.plt %t2.exe | FileCheck -check-prefix=RETPOLINE %s
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// RETPOLINE: Contents of section .got.plt:
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[ELF] Simplify RelRo, TLS, NOBITS section ranks and make RW PT_LOAD start with RelRo
Old: PT_LOAD(.data | PT_GNU_RELRO(.data.rel.ro .bss.rel.ro) | .bss)
New: PT_LOAD(PT_GNU_RELRO(.data.rel.ro .bss.rel.ro) | .data .bss)
The placement of | indicates page alignment caused by PT_GNU_RELRO. The
new layout has simpler rules and saves space for many cases.
Old size: roundup(.data) + roundup(.data.rel.ro)
New size: roundup(.data.rel.ro + .bss.rel.ro) + .data
Other advantages:
* At runtime the 3 memory mappings decrease to 2.
* start(PT_TLS) = start(PT_GNU_RELRO) = start(RW PT_LOAD). This
simplifies binary manipulation tools.
GNU strip before 2.31 discards PT_GNU_RELRO if its
address is not equal to the start of its associated PT_LOAD.
This has been fixed by https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=f2731e0c374e5323ce4cdae2bcc7b7fe22da1a6f
But with this change, we will be compatible with GNU strip before 2.31
* Before, .got.plt (non-relro by default) was placed before .got (relro
by default), which made it impossible to have _GLOBAL_OFFSET_TABLE_
(start of .got.plt on x86-64) equal to the end of .got (R_GOT*_FROM_END)
(https://bugs.llvm.org/show_bug.cgi?id=36555). With the new ordering, we
can improve on this regard if we'd like to.
Reviewers: ruiu, espindola, pcc
Subscribers: emaste, arichardson, llvm-commits, joerg, jdoerfert
Differential Revision: https://reviews.llvm.org/D56828
llvm-svn: 356117
2019-03-14 11:47:45 +08:00
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// RETPOLINE-NEXT: cafe00003000 00200000 feca0000 00000000 00000000
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// RETPOLINE-NEXT: cafe00003010 00000000 00000000 51100000 feca0000
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2018-05-26 05:14:45 +08:00
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2018-05-26 02:26:14 +08:00
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.global _start
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_start:
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jmp bar@PLT
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