Commit-ID: 7a8c54ea75ddc33d65aaf67f6c878b6c71d1ee98
Gitweb: http://git.kernel.org/tip/7a8c54ea75ddc33d65aaf67f6c878b6c71d1ee98
Author: H. Peter Anvin <hpa@xxxxxxxxx>
AuthorDate: Sat, 28 Mar 2009 13:53:26 -0700
Committer: H. Peter Anvin <hpa@xxxxxxxxx>
CommitDate: Sat, 28 Mar 2009 18:14:11 -0700
x86, setup: preemptively save/restore edit and ebp around INT 15 E820
Impact: BIOS bugproofing
Since there are BIOSes known to clobber %ebx and %esi for INT 15 E820,
assume there is something out there clobbering %edi and/or %ebp too,
and don't wait for it to fail.
Signed-off-by: H. Peter Anvin <hpa@xxxxxxxxx>
---
arch/x86/boot/memory.c | 9 +++++----
1 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/arch/x86/boot/memory.c b/arch/x86/boot/memory.c
index a99dbbe..fcdb10a 100644
--- a/arch/x86/boot/memory.c
+++ b/arch/x86/boot/memory.c
@@ -20,7 +20,7 @@ static int detect_memory_e820(void)
{
int count = 0;
u32 next = 0;
- u32 size, id;
+ u32 size, id, edi;
u8 err;
struct e820entry *desc = boot_params.e820_map;
@@ -29,10 +29,11 @@ static int detect_memory_e820(void)
/* Important: %edx and %esi are clobbered by some BIOSes,
so they must be either used for the error output
- or explicitly marked clobbered. */
- asm("int $0x15; setc %0"
+ or explicitly marked clobbered. Given that, assume there
+ is something out there clobbering %ebp and %edi, too. */
+ asm("pushl %%ebp; int $0x15; popl %%ebp; setc %0"
: "=d" (err), "+b" (next), "=a" (id), "+c" (size),
- "=m" (*desc)
+ "=D" (edi), "=m" (*desc)
: "D" (desc), "d" (SMAP), "a" (0xe820)
: "esi");
--
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