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

["H.J. Lu" <hjl.tools@gmail.com>]

On Tue, Jan 8, 2013 at 7:59 AM, Mike Frysinger <vapier@gentoo.org> wrote:
> 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

Can you try this?


-- 
H.J.
---
diff --git a/gdb/common/linux-ptrace.c b/gdb/common/linux-ptrace.c
index 761ef59..cc08b6a 100644
--- a/gdb/common/linux-ptrace.c
+++ b/gdb/common/linux-ptrace.c
@@ -103,21 +103,16 @@ linux_ptrace_test_ret_to_nx (void)
 		 strerror (errno));
       else
 	{
-#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");
+#ifdef __x86_64__
+			: : "r" ((uint64_t) (uintptr_t) (return_address))
 #else
-# error "!__i386__ && !__x86_64__"
+			: : "r" (return_address)
 #endif
+			: "sp", "memory");
 	  gdb_assert_not_reached ("asm block did not terminate");
 	}