x86: explicitly use edx in const delay function. (7e58818d) · Commits · 戴 / test

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>

arch/x86/lib/delay_32.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -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)));

arch/x86/lib/delay_64.c

+9 −2

Original line number	Diff line number	Diff line
		@@ -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)

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