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x86: explicitly use edx in const delay function.

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For x86_64, we can't just use %0, as it would
generate a mul against rdx, which is not really what we
want (note the ">> 32" in x86_64 version).

Using a u64 variable with a shift in i386 generates bad code,
so the solution is to explicitly use %%edx in inline assembly
for both.

Signed-off-by: Glauber Costa <gcosta@redhat.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Glauber Costa 2008-06-24 10:21:25 -03:00 committed by Ingo Molnar
parent a76febe975
commit 7e58818d32
2 changed files with 10 additions and 3 deletions
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2
arch/x86/lib/delay_32.c
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@ -114,7 +114,7 @@ inline void __const_udelay(unsigned long xloops)
int d0;
xloops *= 4;
__asm__("mull %0"
__asm__("mull %%edx"
:"=d" (xloops), "=&a" (d0)
:"1" (xloops), "0"
(cpu_data(raw_smp_processor_id()).loops_per_jiffy * (HZ/4)));

11
arch/x86/lib/delay_64.c
View file

@ -103,9 +103,16 @@ EXPORT_SYMBOL(__delay);
inline void __const_udelay(unsigned long xloops)
{
__delay(((xloops * HZ *
cpu_data(raw_smp_processor_id()).loops_per_jiffy) >> 32) + 1);
int d0;
xloops *= 4;
__asm__("mull %%edx"
:"=d" (xloops), "=&a" (d0)
:"1" (xloops), "0"
(cpu_data(raw_smp_processor_id()).loops_per_jiffy * (HZ/4)));
__delay(++xloops);
}
EXPORT_SYMBOL(__const_udelay);
void __udelay(unsigned long usecs)