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Diffstat (limited to 'drivers/gpu/drm/vmwgfx/vmwgfx_msg.h')
-rw-r--r--drivers/gpu/drm/vmwgfx/vmwgfx_msg.h25
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), \