From 7fc49f19813030f2e15ad2ccec5cb701f7f4a3ec Mon Sep 17 00:00:00 2001
From: Andreas Schwab <schwab@suse.de>
Date: Tue, 27 Jan 2009 21:45:57 +0100
Subject: [PATCH] x86 setup: fix asm constraints in vesa_store_edid
Impact: fix potential miscompile (currently believed non-manifest)
As the comment explains, the VBE DDC call can clobber any register.
Tell the compiler about that fact.
Signed-off-by: Andreas Schwab <schwab@suse.de>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
arch/x86/boot/video-vesa.c | 11 +++++------
1 file changed, 5 insertions(+), 6 deletions(-)
diff --git a/arch/x86/boot/video-vesa.c b/arch/x86/boot/video-vesa.c
index 75115849af330..4a58c8ce3f696 100644
--- a/arch/x86/boot/video-vesa.c
+++ b/arch/x86/boot/video-vesa.c
@@ -269,9 +269,8 @@ void vesa_store_edid(void)
we genuinely have to assume all registers are destroyed here. */
asm("pushw %%es; movw %2,%%es; "INT10"; popw %%es"
- : "+a" (ax), "+b" (bx)
- : "c" (cx), "D" (di)
- : "esi");
+ : "+a" (ax), "+b" (bx), "+c" (cx), "+D" (di)
+ : : "esi", "edx");
if (ax != 0x004f)
return; /* No EDID */
@@ -285,9 +284,9 @@ void vesa_store_edid(void)
dx = 0; /* EDID block number */
di =(size_t) &boot_params.edid_info; /* (ES:)Pointer to block */
asm(INT10
- : "+a" (ax), "+b" (bx), "+d" (dx), "=m" (boot_params.edid_info)
- : "c" (cx), "D" (di)
- : "esi");
+ : "+a" (ax), "+b" (bx), "+d" (dx), "=m" (boot_params.edid_info),
+ "+c" (cx), "+D" (di)
+ : : "esi");
#endif /* CONFIG_FIRMWARE_EDID */
}
--
GitLab