Messages in this thread Patch in this message | | | From | Glauber Costa <> | Subject | [PATCH 04/39] explicitly use edx in const delay function. | Date | Fri, 27 Jun 2008 18:34:11 -0300 |
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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> --- arch/x86/lib/delay_32.c | 2 +- arch/x86/lib/delay_64.c | 11 +++++++++-- 2 files changed, 10 insertions(+), 3 deletions(-)
diff --git a/arch/x86/lib/delay_32.c b/arch/x86/lib/delay_32.c index bf6de05..0b659a3 100644 --- a/arch/x86/lib/delay_32.c +++ b/arch/x86/lib/delay_32.c @@ -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))); diff --git a/arch/x86/lib/delay_64.c b/arch/x86/lib/delay_64.c index d0326d0..ff3dfec 100644 --- a/arch/x86/lib/delay_64.c +++ b/arch/x86/lib/delay_64.c @@ -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) -- 1.5.5.1
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