From 8aa3d340f5612327861f4465550fc8eb39a54d4a Mon Sep 17 00:00:00 2001 From: Andy Whitcroft Date: Fri, 26 Jan 2018 12:36:50 +0000 Subject: [PATCH 07/89] Revert "x86/cpu/AMD: Remove now unused definition of MFENCE_RDTSC feature" CVE-2017-5753 (revert embargoed) CVE-2017-5715 (revert embargoed) This reverts commit 6e6c998937329e9d13d4b239233cd058e8a7730f. Signed-off-by: Andy Whitcroft --- arch/x86/include/asm/barrier.h | 3 ++- arch/x86/include/asm/msr.h | 3 ++- arch/x86/net/bpf_jit_comp.c | 3 +++ 3 files changed, 7 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/barrier.h b/arch/x86/include/asm/barrier.h index d00432579444..aae78054cae2 100644 --- a/arch/x86/include/asm/barrier.h +++ b/arch/x86/include/asm/barrier.h @@ -23,7 +23,8 @@ #define wmb() asm volatile("sfence" ::: "memory") #endif -#define gmb() alternative("", "lfence", X86_FEATURE_LFENCE_RDTSC); +#define gmb() alternative_2("", "mfence", X86_FEATURE_MFENCE_RDTSC, \ + "lfence", X86_FEATURE_LFENCE_RDTSC); #ifdef CONFIG_X86_PPRO_FENCE #define dma_rmb() rmb() diff --git a/arch/x86/include/asm/msr.h b/arch/x86/include/asm/msr.h index 3139098269f6..898dba2e2e2c 100644 --- a/arch/x86/include/asm/msr.h +++ b/arch/x86/include/asm/msr.h @@ -213,7 +213,8 @@ static __always_inline unsigned long long rdtsc_ordered(void) * that some other imaginary CPU is updating continuously with a * time stamp. */ - alternative("", "lfence", X86_FEATURE_LFENCE_RDTSC); + alternative_2("", "mfence", X86_FEATURE_MFENCE_RDTSC, + "lfence", X86_FEATURE_LFENCE_RDTSC); return rdtsc(); } diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index e20e304320f9..879dbfefb66d 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -116,6 +116,9 @@ static void emit_memory_barrier(u8 **pprog) if (boot_cpu_has(X86_FEATURE_LFENCE_RDTSC)) /* x86 LFENCE opcode 0F AE E8 */ EMIT3(0x0f, 0xae, 0xe8); + else if (boot_cpu_has(X86_FEATURE_MFENCE_RDTSC)) + /* AMD MFENCE opcode 0F AE F0 */ + EMIT3(0x0f, 0xae, 0xf0); else /* we should never end up here, * but if we do, better not to emit anything*/ -- 2.15.1