From: David Woodhouse <dwmw@amazon.co.uk>
To: arjan@linux.intel.com, tglx@linutronix.de, karahmed@amazon.de,
x86@kernel.org, linux-kernel@vger.kernel.org,
tim.c.chen@linux.intel.com, bp@alien8.de, peterz@infradead.org,
pbonzini@redhat.com, ak@linux.intel.com,
torvalds@linux-foundation.org, gregkh@linux-foundation.org,
dave.hansen@intel.com
Subject: [PATCH 3/3] x86/speculation: Simplify indirect_branch_prediction_barrier()
Date: Sat, 27 Jan 2018 16:24:34 +0000 [thread overview]
Message-ID: <1517070274-12128-4-git-send-email-dwmw@amazon.co.uk> (raw)
In-Reply-To: <1517070274-12128-1-git-send-email-dwmw@amazon.co.uk>
From: Borislav Petkov <bp@suse.de>
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>
---
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 0c6dd43..dd99808 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -303,3 +303,9 @@ ssize_t cpu_show_spectre_v2(struct device *dev,
spectre_v2_bad_module ? " - vulnerable module loaded" : "");
}
#endif
+
+void __ibp_barrier(void)
+{
+ __wrmsr(MSR_IA32_PRED_CMD, PRED_CMD_IBPB, 0);
+}
+EXPORT_SYMBOL_GPL(__ibp_barrier);
--
2.7.4
next prev parent reply other threads:[~2018-01-27 16:24 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-27 16:24 [PATCH 0/3] Speculation CPU feature cleanups David Woodhouse
2018-01-27 16:24 ` [PATCH 1/3] x86/cpufeatures: Clean up Spectre v2 related CPUID flags David Woodhouse
2018-01-27 18:16 ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-27 16:24 ` [PATCH 2/3] x86/retpoline: Simplify vmexit_fill_RSB() David Woodhouse
2018-01-27 18:16 ` [tip:x86/pti] " tip-bot for Borislav Petkov
2018-01-27 16:24 ` David Woodhouse [this message]
2018-01-27 18:17 ` [tip:x86/pti] x86/speculation: Simplify indirect_branch_prediction_barrier() tip-bot for Borislav Petkov
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