Re: [PATCH] gdb: x86: fix x32 builds with inline asm

Mike Frysinger
2013-01-08T15:57:24Z

[-- Attachment #1: Type: Text/Plain, Size: 1232 bytes --]

On Tuesday 08 January 2013 10:01:20 Mike Frysinger wrote:
> -#if defined __i386__
> - asm volatile ("pushl %0;"
> - ".globl linux_ptrace_test_ret_to_nx_instr;"
> - "linux_ptrace_test_ret_to_nx_instr:"
> - "ret"
> - : : "r" (return_address) : "%esp", "memory");
> -#elif defined __x86_64__
> - asm volatile ("pushq %0;"
> + asm volatile ("push %0;"
> ".globl linux_ptrace_test_ret_to_nx_instr;"
> "linux_ptrace_test_ret_to_nx_instr:"
> "ret"
> - : : "r" (return_address) : "%rsp", "memory");
> -#else
> -# error "!__i386__ && !__x86_64__"
> -#endif
> + : : "r" (return_address) : "sp", "memory");

hrm, this works for -m32 and -m64, but doesn't actually help with -mx32. this
doesn't seem to line up with my expectations. can you suggest something here
H.J. Lu ?

$ cat test.c
main() { asm volatile ("push %0; ret;" : : "r"(main) : "sp", "memory"); }

$ gcc -m32 test.c
8: 50 push %eax
9: c3 ret

$ gcc -m64 test.c
9: 50 push %rax
a: c3 retq

$ gcc -mx32 test.c
test.c: Assembler messages:
test.c:2: Error: operand type mismatch for `push'
-mike

[-- Attachment #2: This is a digitally signed message part. --]
[-- Type: application/pgp-signature, Size: 836 bytes --]