Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 64e16720 authored by Borislav Petkov's avatar Borislav Petkov Committed by Thomas Gleixner
Browse files

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: default avatarBorislav Petkov <bp@suse.de>
Signed-off-by: default avatarDavid Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: default avatarThomas 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
parent 1dde7415

arch/x86/include/asm/nospec-branch.h

+4 −9
Original line number Diff line number Diff line
@@ -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__ */

arch/x86/include/asm/processor.h

+3 −0
Original line number Diff line number Diff line
@@ -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 */

arch/x86/kernel/cpu/bugs.c

+6 −0
Original line number Diff line number Diff line
@@ -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);