[PATCH 05/11] x86/retpoline/hyperv: Convert assembler indirect jumps

From: Andi Kleen
Date: Wed Jan 03 2018 - 18:09:54 EST


From: Andi Kleen <ak@xxxxxxxxxxxxxxx>

Convert all indirect jumps in hyperv inline asm code to use
non speculative sequences.

Based on code from David Woodhouse and Tim Chen

Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
---
arch/x86/include/asm/mshyperv.h | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index 5400add2885b..2dfcdd401d4c 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -7,6 +7,7 @@
#include <linux/nmi.h>
#include <asm/io.h>
#include <asm/hyperv.h>
+#include <asm/jump-asm.h>

/*
* The below CPUID leaves are present if VersionAndFeatures.HypervisorPresent
@@ -186,7 +187,7 @@ static inline u64 hv_do_hypercall(u64 control, void *input, void *output)
return U64_MAX;

__asm__ __volatile__("mov %4, %%r8\n"
- "call *%5"
+ NOSPEC_CALL("%5")
: "=a" (hv_status), ASM_CALL_CONSTRAINT,
"+c" (control), "+d" (input_address)
: "r" (output_address), "m" (hv_hypercall_pg)
@@ -200,7 +201,7 @@ static inline u64 hv_do_hypercall(u64 control, void *input, void *output)
if (!hv_hypercall_pg)
return U64_MAX;

- __asm__ __volatile__("call *%7"
+ __asm__ __volatile__(NOSPEC_CALL("%7")
: "=A" (hv_status),
"+c" (input_address_lo), ASM_CALL_CONSTRAINT
: "A" (control),
@@ -227,7 +228,7 @@ static inline u64 hv_do_fast_hypercall8(u16 code, u64 input1)

#ifdef CONFIG_X86_64
{
- __asm__ __volatile__("call *%4"
+ __asm__ __volatile__(NOSPEC_CALL("%4")
: "=a" (hv_status), ASM_CALL_CONSTRAINT,
"+c" (control), "+d" (input1)
: "m" (hv_hypercall_pg)
@@ -238,7 +239,7 @@ static inline u64 hv_do_fast_hypercall8(u16 code, u64 input1)
u32 input1_hi = upper_32_bits(input1);
u32 input1_lo = lower_32_bits(input1);

- __asm__ __volatile__ ("call *%5"
+ __asm__ __volatile__ (NOSPEC_CALL("%5")
: "=A"(hv_status),
"+c"(input1_lo),
ASM_CALL_CONSTRAINT
--
2.14.3