Messages in this thread |  | | | Subject | Re: [PATCH] slub: Disable the lockless allocator | | From | Eric Dumazet <> | | Date | Sun, 27 Mar 2011 09:52:27 +0200 |
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Le samedi 26 mars 2011 à 20:57 -0500, Christoph Lameter a écrit : > But then the same fix must also be used in the asm code or the fallback > (turns out that the fallback is always used in kmem_cache_init since > the instruction patching comes later). > > Patch boots fine both in UP and SMP mode > > > > > Subject: percpu: Omit segment prefix in the UP case for cmpxchg_double > > Omit the segment prefix in the UP case. GS is not used then > and we will generate segfaults if cmpxchg16b is used otherwise. > > Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> > Signed-off-by: Christoph Lameter <cl@linux.com> > > arch/x86/include/asm/percpu.h | 10 ++++++---- > 1 files changed, 6 insertions(+), 4 deletions(-) > > Index: linux-2.6/arch/x86/include/asm/percpu.h > =================================================================== > --- linux-2.6.orig/arch/x86/include/asm/percpu.h 2011-03-26 20:43:03.994089001 -0500 > +++ linux-2.6/arch/x86/include/asm/percpu.h 2011-03-26 20:43:22.414089004 -0500 > @@ -45,7 +45,7 @@ > #include <linux/stringify.h> > > #ifdef CONFIG_SMP > -#define __percpu_arg(x) "%%"__stringify(__percpu_seg)":%P" #x > +#define __percpu_prefix "%%"__stringify(__percpu_seg)":" > #define __my_cpu_offset percpu_read(this_cpu_off) > > /* > @@ -62,9 +62,11 @@ > (typeof(*(ptr)) __kernel __force *)tcp_ptr__; \ > }) > #else > -#define __percpu_arg(x) "%P" #x > +#define __percpu_prefix "" > #endif > > +#define __percpu_arg(x) __percpu_prefix "%P" #x > + > /* > * Initialized pointers to per-cpu variables needed for the boot > * processor need to use these macros to get the proper address > @@ -516,11 +518,11 @@ > typeof(o2) __n2 = n2; \ > typeof(o2) __dummy; \ > alternative_io("call this_cpu_cmpxchg16b_emu\n\t" P6_NOP4, \
I guess you should make P6_NOP4 be P6_NOP3 in !SMP builds.
> - "cmpxchg16b %%gs:(%%rsi)\n\tsetz %0\n\t", \ > + "cmpxchg16b " __percpu_prefix "(%%rsi)\n\tsetz %0\n\t", \ > X86_FEATURE_CX16, \ > ASM_OUTPUT2("=a"(__ret), "=d"(__dummy)), \ > "S" (&pcp1), "b"(__n1), "c"(__n2), \ > - "a"(__o1), "d"(__o2)); \ > + "a"(__o1), "d"(__o2) : "memory"); \ > __ret; \ > }) >
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