diff options
Diffstat (limited to 'tools/include')
| -rw-r--r-- | tools/include/nolibc/nolibc.h | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/tools/include/nolibc/nolibc.h b/tools/include/nolibc/nolibc.h index 96b6d56acb57..7f300dc379e7 100644 --- a/tools/include/nolibc/nolibc.h +++ b/tools/include/nolibc/nolibc.h @@ -583,13 +583,21 @@ struct sys_stat_struct { }) /* startup code */ +/* + * i386 System V ABI mandates: + * 1) last pushed argument must be 16-byte aligned. + * 2) The deepest stack frame should be set to zero + * + */ asm(".section .text\n" ".global _start\n" "_start:\n" "pop %eax\n" // argc (first arg, %eax) "mov %esp, %ebx\n" // argv[] (second arg, %ebx) "lea 4(%ebx,%eax,4),%ecx\n" // then a NULL then envp (third arg, %ecx) - "and $-16, %esp\n" // x86 ABI : esp must be 16-byte aligned when + "xor %ebp, %ebp\n" // zero the stack frame + "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 "push %ebx\n" // support both regparm and plain stack modes "push %eax\n" |