[Mesa-dev] [PATCH] mapi: update the asm code to support x32

[Ilia Mirkin]

This seems reasonable. I spent a bit of time thinking about how this
could be improved, but couldn't come up with anything. Going to leave
this on-list for a bit though so others better versed in the mapi
logic can provide feedback. In the meanwhile, this is

Reviewed-by: Ilia Mirkin <imirkin at alum.mit.edu>

On Sun, Jan 8, 2017 at 12:38 PM, Grazvydas Ignotas <notasas at gmail.com> wrote:
> Fixes crashes when both glx-tls and asm are enabled on x32.
>
> Cc: mesa-stable at lists.freedesktop.org
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94512
> Signed-off-by: Grazvydas Ignotas <notasas at gmail.com>
> ---
> no commit access, please push
>
>  src/mapi/entry_x86-64_tls.h | 31 ++++++++++++++++++++++++++++---
>  1 file changed, 28 insertions(+), 3 deletions(-)
>
> diff --git a/src/mapi/entry_x86-64_tls.h b/src/mapi/entry_x86-64_tls.h
> index 8f3fa91..1e29bde 100644
> --- a/src/mapi/entry_x86-64_tls.h
> +++ b/src/mapi/entry_x86-64_tls.h
> @@ -41,11 +41,23 @@ __asm__(".text\n"
>     ".balign 32\n"                                        \
>     func ":"
>
> +#ifndef __ILP32__
> +
>  #define STUB_ASM_CODE(slot)                              \
>     "movq " ENTRY_CURRENT_TABLE "@GOTTPOFF(%rip), %rax\n\t"  \
>     "movq %fs:(%rax), %r11\n\t"                           \
>     "jmp *(8 * " slot ")(%r11)"
>
> +#else
> +
> +#define STUB_ASM_CODE(slot)                              \
> +   "movq " ENTRY_CURRENT_TABLE "@GOTTPOFF(%rip), %rax\n\t"  \
> +   "movl %fs:(%rax), %r11d\n\t"                          \
> +   "movl 4*" slot "(%r11d), %r11d\n\t"                   \
> +   "jmp *%r11"
> +
> +#endif
> +
>  #define MAPI_TMP_STUB_ASM_GCC
>  #include "mapi_tmp.h"
>
> @@ -72,19 +84,32 @@ void
>  entry_patch(mapi_func entry, int slot)
>  {
>     char *code = (char *) entry;
> -   *((unsigned int *) (code + 12)) = slot * sizeof(mapi_func);
> +   int offset = 12;
> +#ifdef __ILP32__
> +   offset = 13;
> +#endif
> +   *((unsigned int *) (code + offset)) = slot * sizeof(mapi_func);
>  }
>
>  mapi_func
>  entry_generate(int slot)
>  {
> -   const char code_templ[16] = {
> +   const char code_templ[] = {
> +#ifndef __ILP32__
>        /* movq %fs:0, %r11 */
>        0x64, 0x4c, 0x8b, 0x1c, 0x25, 0x00, 0x00, 0x00, 0x00,
>        /* jmp *0x1234(%r11) */
>        0x41, 0xff, 0xa3, 0x34, 0x12, 0x00, 0x00,
> +#else
> +      /* movl %fs:0, %r11d */
> +      0x64, 0x44, 0x8b, 0x1c, 0x25, 0x00, 0x00, 0x00, 0x00,
> +      /* movl 0x1234(%r11d), %r11d */
> +      0x67, 0x45, 0x8b, 0x9b, 0x34, 0x12, 0x00, 0x00,
> +      /* jmp *%r11 */
> +      0x41, 0xff, 0xe3,
> +#endif
>     };
> -   unsigned long addr;
> +   unsigned long long addr;
>     char *code;
>     mapi_func entry;
>
> --
> 2.7.4
>
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