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authorBorislav Petkov <bp@suse.de>2018-01-27 16:24:34 +0000
committerThomas Gleixner <tglx@linutronix.de>2018-01-27 19:10:45 +0100
commit64e16720ea0879f8ab4547e3b9758936d483909b (patch)
treee8f8f39b1bfc79990ae218f451e035724d8e2d87 /arch
parent1dde7415e99933bb7293d6b2843752cbdb43ec11 (diff)
downloadlinux-64e16720ea0879f8ab4547e3b9758936d483909b.tar.bz2
x86/speculation: Simplify indirect_branch_prediction_barrier()
Make it all a function which does the WRMSR instead of having a hairy inline asm. [dwmw2: export it, fix CONFIG_RETPOLINE issues] Signed-off-by: Borislav Petkov <bp@suse.de> Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: ak@linux.intel.com Cc: dave.hansen@intel.com Cc: karahmed@amazon.de Cc: arjan@linux.intel.com Cc: torvalds@linux-foundation.org Cc: peterz@infradead.org Cc: bp@alien8.de Cc: pbonzini@redhat.com Cc: tim.c.chen@linux.intel.com Cc: gregkh@linux-foundation.org Link: https://lkml.kernel.org/r/1517070274-12128-4-git-send-email-dwmw@amazon.co.uk
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/include/asm/nospec-branch.h13
-rw-r--r--arch/x86/include/asm/processor.h3
-rw-r--r--arch/x86/kernel/cpu/bugs.c6
3 files changed, 13 insertions, 9 deletions
diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h
index df4ececa6ebf..d15d471348b8 100644
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -164,15 +164,10 @@ static inline void vmexit_fill_RSB(void)
static inline void indirect_branch_prediction_barrier(void)
{
- asm volatile(ALTERNATIVE("",
- "movl %[msr], %%ecx\n\t"
- "movl %[val], %%eax\n\t"
- "movl $0, %%edx\n\t"
- "wrmsr",
- X86_FEATURE_USE_IBPB)
- : : [msr] "i" (MSR_IA32_PRED_CMD),
- [val] "i" (PRED_CMD_IBPB)
- : "eax", "ecx", "edx", "memory");
+ alternative_input("",
+ "call __ibp_barrier",
+ X86_FEATURE_USE_IBPB,
+ ASM_NO_INPUT_CLOBBER("eax", "ecx", "edx", "memory"));
}
#endif /* __ASSEMBLY__ */
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 9c18da64daa9..881ca3b1d6d4 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -970,4 +970,7 @@ bool xen_set_default_idle(void);
void stop_this_cpu(void *dummy);
void df_debug(struct pt_regs *regs, long error_code);
+
+void __ibp_barrier(void);
+
#endif /* _ASM_X86_PROCESSOR_H */
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 32d8e6cdc09e..3bfb2b23d79c 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -311,3 +311,9 @@ ssize_t cpu_show_spectre_v2(struct device *dev,
spectre_v2_module_string());
}
#endif
+
+void __ibp_barrier(void)
+{
+ __wrmsr(MSR_IA32_PRED_CMD, PRED_CMD_IBPB, 0);
+}
+EXPORT_SYMBOL_GPL(__ibp_barrier);