llvm-project

Commit Graph

Author	SHA1	Message	Date
Fangrui Song	ee9a251caf	[ELF] Set DF_1_PIE for -pie DF_1_PIE originated from Solaris (https://docs.oracle.com/cd/E36784_01/html/E36857/chapter6-42444.html ). GNU ld since https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=5fe2850dd96483f176858fd75c098313d5b20bc2 sets the flag on non-Solaris platforms. It can help distinguish PIE from ET_DYN. eu-classify from elfutils uses this to recognize PIE (https://sourceware.org/git/?p=elfutils.git;a=commit;h=3f489b5c7c78df6d52f8982f79c36e9a220e8951 ) glibc uses this flag to reject dlopen'ing a PIE (https://sourceware.org/bugzilla/show_bug.cgi?id=24323 ) Reviewed By: psmith Differential Revision: https://reviews.llvm.org/D80872	2020-06-01 10:19:41 -07:00
Fangrui Song	523f999acf	[ELF][RISCV] Allow PT_LOAD to have overlapping p_offset ranges on EM_RISCV Port the D64906 technique to RISC-V. It deletes 3 alignments at PT_LOAD boundaries for the default case: the size of a RISC-V binary decreases by at most 12kb. llvm-svn: 370192	2019-08-28 12:06:06 +00:00
Fangrui Song	5b4285d82d	[ELF][RISCV] Create dummy .sdata for __global_pointer$ if .sdata does not exist If .sdata is absent, linker synthesized __global_pointer$ gets a section index of SHN_ABS. (ld.bfd has a similar issue: binutils PR24678) Scrt1.o may use `lla gp, __global_pointer$` to reference the symbol PC relatively. In -pie/-shared mode, lld complains if a PC relative relocation references an absolute symbol (SHN_ABS) but ld.bfd doesn't: ld.lld: error: relocation R_RISCV_PCREL_HI20 cannot refer to lute symbol: __global_pointer$ Let the reference of __global_pointer$ to force creation of .sdata to fix the problem. This is similar to _GLOBAL_OFFSET_TABLE_, which forces creation of .got or .got.plt . Also, change the visibility from STV_HIDDEN to STV_DEFAULT and don't define the symbol for -shared. This matches ld.bfd, though I don't understand why it uses STV_DEFAULT. Reviewed By: ruiu, jrtc27 Differential Revision: https://reviews.llvm.org/D63132 llvm-svn: 363351	2019-06-14 02:14:53 +00:00

Author

SHA1

Message

Date

Fangrui Song

ee9a251caf

[ELF] Set DF_1_PIE for -pie

DF_1_PIE originated from Solaris (https://docs.oracle.com/cd/E36784_01/html/E36857/chapter6-42444.html ).
GNU ld since
https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=5fe2850dd96483f176858fd75c098313d5b20bc2
sets the flag on non-Solaris platforms.

It can help distinguish PIE from ET_DYN.
eu-classify from elfutils uses this to recognize PIE (https://sourceware.org/git/?p=elfutils.git;a=commit;h=3f489b5c7c78df6d52f8982f79c36e9a220e8951 )

glibc uses this flag to reject dlopen'ing a PIE (https://sourceware.org/bugzilla/show_bug.cgi?id=24323 )

Reviewed By: psmith

Differential Revision: https://reviews.llvm.org/D80872

2020-06-01 10:19:41 -07:00

Fangrui Song

523f999acf

[ELF][RISCV] Allow PT_LOAD to have overlapping p_offset ranges on EM_RISCV

Port the D64906 technique to RISC-V. It deletes 3 alignments at
PT_LOAD boundaries for the default case: the size of a RISC-V binary
decreases by at most 12kb.

llvm-svn: 370192

2019-08-28 12:06:06 +00:00

Fangrui Song

5b4285d82d

[ELF][RISCV] Create dummy .sdata for __global_pointer$ if .sdata does not exist

If .sdata is absent, linker synthesized __global_pointer$ gets a section index of SHN_ABS.
(ld.bfd has a similar issue: binutils PR24678)

Scrt1.o may use `lla gp, __global_pointer$` to reference the symbol PC
relatively. In -pie/-shared mode, lld complains if a PC relative
relocation references an absolute symbol (SHN_ABS) but ld.bfd doesn't:

    ld.lld: error: relocation R_RISCV_PCREL_HI20 cannot refer to lute symbol: __global_pointer$

Let the reference of __global_pointer$ to force creation of .sdata to
fix the problem. This is similar to _GLOBAL_OFFSET_TABLE_, which forces
creation of .got or .got.plt .

Also, change the visibility from STV_HIDDEN to STV_DEFAULT and don't
define the symbol for -shared. This matches ld.bfd, though I don't
understand why it uses STV_DEFAULT.

Reviewed By: ruiu, jrtc27

Differential Revision: https://reviews.llvm.org/D63132

llvm-svn: 363351

2019-06-14 02:14:53 +00:00

3 Commits