diff options
| author | Dmitry Chagin <dchagin@FreeBSD.org> | 2023-07-11 12:10:32 +0000 |
|---|---|---|
| committer | Dmitry Chagin <dchagin@FreeBSD.org> | 2023-07-11 12:10:32 +0000 |
| commit | e541cf8316bb787df0f19c43132c517482cf24a6 (patch) | |
| tree | 9610b23e677ccc92a5256bb718b37efc8f6eb7c4 /libexec/rtld-elf | |
| parent | 86c63225ea21f2b4c0926bde9d9d4da1ec891b06 (diff) | |
rtld: Annotate .rtld_start on i386
Add a stop indicator to rtld_start to satisfy unwinders:
The right unwinding stop indicator should be CFI-undefined PC.
https://dwarfstd.org/doc/Dwarf3.pdf - page 118:
If a Return Address register is defined in the virtual unwind table,
and its rule is undefined (for example, by DW_CFA_undefined), then
there is no return address and no call address, and the virtual
unwind of stack activations is complete.
That is allows gdb and libunwind successfully stop when unwinding stack
from global constructors and destructors.
Reviewed by: kib
Differential Revision: https://reviews.freebsd.org/D40949
Diffstat (limited to 'libexec/rtld-elf')
| -rw-r--r-- | libexec/rtld-elf/i386/rtld_start.S | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/libexec/rtld-elf/i386/rtld_start.S b/libexec/rtld-elf/i386/rtld_start.S index 6dbae220d89c..656ebb13864f 100644 --- a/libexec/rtld-elf/i386/rtld_start.S +++ b/libexec/rtld-elf/i386/rtld_start.S @@ -30,8 +30,15 @@ .globl .rtld_start .type .rtld_start,@function .rtld_start: + .cfi_startproc + .cfi_undefined %eip xorl %ebp,%ebp # Clear frame pointer for good form movl %esp,%esi # Save initial stack pointer + pushl %ebp + .cfi_def_cfa_offset 4 + movl %esp,%ebp + .cfi_offset %ebp,-4 + .cfi_def_cfa_register %ebp andl $0xfffffff0,%esp # Align stack pointer subl $16,%esp # A place to store exit procedure addr movl %esp,%ebx # save address of exit proc @@ -53,6 +60,7 @@ .globl .rtld_goto_main .rtld_goto_main: # This symbol exists just to make debugging easier. jmp *%eax # Enter main program + .cfi_endproc /* |