diff options
| author | Willy Tarreau <w@1wt.eu> | 2023-01-10 08:24:25 +0100 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2023-01-10 13:33:56 -0800 |
| commit | 2ab4aa487b93d9d994b4a20382848a4041f00d78 (patch) | |
| tree | f5a49a4fd583899aaeccd3db9c102df7c8285e48 | |
| parent | 9e5bdc613d06fdc6fed73267767c09a0dc0c6aac (diff) | |
tools/nolibc: add auxiliary vector retrieval for i386
In the _start block we now iterate over envp to find the auxiliary
vector after the NULL. The pointer is saved into an _auxv variable
that is marked as weak so that it's accessible from multiple units.
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
| -rw-r--r-- | tools/include/nolibc/arch-i386.h | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/tools/include/nolibc/arch-i386.h b/tools/include/nolibc/arch-i386.h index 60b586120727..e8d0cf545bf1 100644 --- a/tools/include/nolibc/arch-i386.h +++ b/tools/include/nolibc/arch-i386.h @@ -179,6 +179,7 @@ struct sys_stat_struct { }) char **environ __attribute__((weak)); +const unsigned long *_auxv __attribute__((weak)); /* startup code */ /* @@ -195,6 +196,12 @@ void __attribute__((weak,noreturn,optimize("omit-frame-pointer"))) _start(void) "lea 4(%ebx,%eax,4),%ecx\n" // then a NULL then envp (third arg, %ecx) "mov %ecx, environ\n" // save environ "xor %ebp, %ebp\n" // zero the stack frame + "mov %ecx, %edx\n" // search for auxv (follows NULL after last env) + "0:\n" + "add $4, %edx\n" // search for auxv using edx, it follows the + "cmp -4(%edx), %ebp\n" // ... NULL after last env (ebp is zero here) + "jnz 0b\n" + "mov %edx, _auxv\n" // save it into _auxv "and $-16, %esp\n" // x86 ABI : esp must be 16-byte aligned before "sub $4, %esp\n" // the call instruction (args are aligned) "push %ecx\n" // push all registers on the stack so that we |