diff options
| author | Willy Tarreau <w@1wt.eu> | 2023-01-10 08:24:26 +0100 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2023-01-10 13:33:56 -0800 |
| commit | 1cce162ab4a565c8a88ffac1d9f78c80e160d6a1 (patch) | |
| tree | 436a262f976fd92a1738e6c615e44fedb0fb871c /tools/include | |
| parent | 2ab4aa487b93d9d994b4a20382848a4041f00d78 (diff) | |
tools/nolibc: add auxiliary vector retrieval for x86_64
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>
Diffstat (limited to 'tools/include')
| -rw-r--r-- | tools/include/nolibc/arch-x86_64.h | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/tools/include/nolibc/arch-x86_64.h b/tools/include/nolibc/arch-x86_64.h index 683702a16a61..17f6751208e7 100644 --- a/tools/include/nolibc/arch-x86_64.h +++ b/tools/include/nolibc/arch-x86_64.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 8(%rsi,%rdi,8),%rdx\n" // then a NULL then envp (third arg, %rdx) "mov %rdx, environ\n" // save environ "xor %ebp, %ebp\n" // zero the stack frame + "mov %rdx, %rax\n" // search for auxv (follows NULL after last env) + "0:\n" + "add $8, %rax\n" // search for auxv using rax, it follows the + "cmp -8(%rax), %rbp\n" // ... NULL after last env (rbp is zero here) + "jnz 0b\n" + "mov %rax, _auxv\n" // save it into _auxv "and $-16, %rsp\n" // x86 ABI : esp must be 16-byte aligned before call "call main\n" // main() returns the status code, we'll exit with it. "mov %eax, %edi\n" // retrieve exit code (32 bit) |