Commit-ID: 64e16720ea0879f8ab4547e3b9758936d483909b
Gitweb: https://git.kernel.org/tip/64e16720ea0879f8ab4547e3b9758936d483909b
Author: Borislav Petkov <bp@xxxxxxx>
AuthorDate: Sat, 27 Jan 2018 16:24:34 +0000
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Sat, 27 Jan 2018 19:10:45 +0100
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@xxxxxxx>
Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: ak@xxxxxxxxxxxxxxx
Cc: dave.hansen@xxxxxxxxx
Cc: karahmed@xxxxxxxxx
Cc: arjan@xxxxxxxxxxxxxxx
Cc: torvalds@xxxxxxxxxxxxxxxxxxxx
Cc: peterz@xxxxxxxxxxxxx
Cc: bp@xxxxxxxxx
Cc: pbonzini@xxxxxxxxxx
Cc: tim.c.chen@xxxxxxxxxxxxxxx
Cc: gregkh@xxxxxxxxxxxxxxxxxxxx
Link: https://lkml.kernel.org/r/1517070274-12128-4-git-send-email-dwmw@xxxxxxxxxxxx
---
arch/x86/include/asm/nospec-branch.h | 13 ++++---------
arch/x86/include/asm/processor.h | 3 +++
arch/x86/kernel/cpu/bugs.c | 6 ++++++
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 df4ececa..d15d471 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 9c18da6..881ca3b 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 32d8e6c..3bfb2b2 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);
--
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