diff options
Diffstat (limited to 'drivers/gpu/drm/vmwgfx/vmwgfx_msg.h')
| -rw-r--r-- | drivers/gpu/drm/vmwgfx/vmwgfx_msg.h | 25 |
1 files changed, 17 insertions, 8 deletions
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_msg.h b/drivers/gpu/drm/vmwgfx/vmwgfx_msg.h index 557a033fb610..8545488aa0cf 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_msg.h +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_msg.h @@ -135,17 +135,24 @@ #else -/* In the 32-bit version of this macro, we use "m" because there is no - * more register left for bp +/* + * In the 32-bit version of this macro, we store bp in a memory location + * because we've ran out of registers. + * Now we can't reference that memory location while we've modified + * %esp or %ebp, so we first push it on the stack, just before we push + * %ebp, and then when we need it we read it from the stack where we + * just pushed it. */ #define VMW_PORT_HB_OUT(cmd, in_ecx, in_si, in_di, \ port_num, magic, bp, \ eax, ebx, ecx, edx, si, di) \ ({ \ - asm volatile ("push %%ebp;" \ - "mov %12, %%ebp;" \ + asm volatile ("push %12;" \ + "push %%ebp;" \ + "mov 0x04(%%esp), %%ebp;" \ "rep outsb;" \ - "pop %%ebp;" : \ + "pop %%ebp;" \ + "add $0x04, %%esp;" : \ "=a"(eax), \ "=b"(ebx), \ "=c"(ecx), \ @@ -167,10 +174,12 @@ port_num, magic, bp, \ eax, ebx, ecx, edx, si, di) \ ({ \ - asm volatile ("push %%ebp;" \ - "mov %12, %%ebp;" \ + asm volatile ("push %12;" \ + "push %%ebp;" \ + "mov 0x04(%%esp), %%ebp;" \ "rep insb;" \ - "pop %%ebp" : \ + "pop %%ebp;" \ + "add $0x04, %%esp;" : \ "=a"(eax), \ "=b"(ebx), \ "=c"(ecx), \ |