tip-bot for H. Peter Anvin wrote:
> Commit-ID: f88731e3068f9d1392ba71cc9f50f035d26a0d4f
> Gitweb: http://git.kernel.org/tip/f88731e3068f9d1392ba71cc9f50f035d26a0d4f
> Author: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
> AuthorDate: Wed, 9 Jun 2010 16:03:09 -0700
> Committer: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
> CommitDate: Wed, 9 Jun 2010 16:03:09 -0700
>
> x86, alternatives: Use 16-bit numbers for cpufeature index
>
> We already have cpufeature indicies above 255, so use a 16-bit number
> for the alternatives index. This consumes a padding field and so
> doesn't add any size, but it means that abusing the padding field to
> create assembly errors on overflow no longer works. We can retain the
> test simply by redirecting it to the .discard section, however.
>
My machine hits "invalid opcode" at *prepare_to_copy+0x79,
and it can't boot up.
(gdb) l *prepare_to_copy+0x79
0xc0101789 is in prepare_to_copy (/home/njubee/work/linux-2.6-tip/arch/x86/include/asm/xsave.h:118).
113
114 static inline void fpu_xsave(struct fpu *fpu)
115 {
116 /* This, however, we can work around by forcing the compiler to select
117 an addressing mode that doesn't require extended registers. */
118 __asm__ __volatile__(".byte " REX_PREFIX "0x0f,0xae,0x27"
119 : : "D" (&(fpu->state->xsave)),
120 "a" (-1), "d"(-1) : "memory");
121 }
122 #endif
It can boot up if this patch is reverted.
Does this patch change the return value of "use_xsave()"
cat /proc/cpuinfo
processor : 0
vendor_id : GenuineIntel
cpu family : 15
model : 4
model name : Intel(R) Pentium(R) D CPU 2.80GHz
stepping : 8
cpu MHz : 2800.120
cache size : 1024 KB
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 5
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss constant_tsc pebs bts tsc_reliable pni ds_cpl
bogomips : 5600.24
clflush size : 64
cache_alignment : 128
address sizes : 36 bits physical, 48 bits virtual
power management:
processor : 1
vendor_id : GenuineIntel
cpu family : 15
model : 4
model name : Intel(R) Pentium(R) D CPU 2.80GHz
stepping : 8
cpu MHz : 2800.120
cache size : 1024 KB
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 5
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss constant_tsc pebs bts tsc_reliable pni ds_cpl
bogomips : 5574.36
clflush size : 64
cache_alignment : 128
address sizes : 36 bits physical, 48 bits virtual
power management:
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