From: Linus Torvalds Date: Sat, 17 Sep 2005 22:41:04 +0000 (-0700) Subject: x86-64/smp: fix random SIGSEGV issues X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=bc5e8fdfc622b03acf5ac974a1b8b26da6511c99;p=GitHub%2Fexynos8895%2Fandroid_kernel_samsung_universal8895.git x86-64/smp: fix random SIGSEGV issues They seem to have been due to AMD errata 63/122; the fix is to disable TLB flush filtering in SMP configurations. Confirmed to fix the problem by Andrew Walrond [ Let's see if we'll have a better fix eventually, this is the Q&D "let's get this fixed and out there" version ] Signed-off-by: Linus Torvalds --- diff --git a/arch/x86_64/kernel/setup.c b/arch/x86_64/kernel/setup.c index 351d8d64c2fb..238f73e1a834 100644 --- a/arch/x86_64/kernel/setup.c +++ b/arch/x86_64/kernel/setup.c @@ -831,11 +831,26 @@ static void __init amd_detect_cmp(struct cpuinfo_x86 *c) #endif } +#define HWCR 0xc0010015 + static int __init init_amd(struct cpuinfo_x86 *c) { int r; int level; +#ifdef CONFIG_SMP + unsigned long value; + + // Disable TLB flush filter by setting HWCR.FFDIS: + // bit 6 of msr C001_0015 + // + // Errata 63 for SH-B3 steppings + // Errata 122 for all(?) steppings + rdmsrl(HWCR, value); + value |= 1 << 6; + wrmsrl(HWCR, value); +#endif + /* Bit 31 in normal CPUID used for nonstandard 3DNow ID; 3DNow is IDd by bit 31 in extended CPUID (1*32+31) anyway */ clear_bit(0*32+31, &c->x86_capability);