[PATCH 5.9 659/757] x86/mce: Annotate mce_rd/wrmsrl() with noinstr

Greg Kroah-Hartman
2020-10-27T16:33:43Z

From: Borislav Petkov <bp@suse.de>

[ Upstream commit e100777016fdf6ec3a9d7c1773b15a2b5eca6c55 ]

They do get called from the #MC handler which is already marked
"noinstr".

Commit

e2def7d49d08 ("x86/mce: Make mce_rdmsrl() panic on an inaccessible MSR")

already got rid of the instrumentation in the MSR accessors, fix the
annotation now too, in order to get rid of:

vmlinux.o: warning: objtool: do_machine_check()+0x4a: call to mce_rdmsrl() leaves .noinstr.text section

Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200915194020.28807-1-bp@alien8.de
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/x86/kernel/cpu/mce/core.c | 27 +++++++++++++++++++++------
1 file changed, 21 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
index fc4f8c04bdb56..4288645425f15 100644
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -374,16 +374,25 @@ static int msr_to_offset(u32 msr)
}

/* MSR access wrappers used for error injection */
-static u64 mce_rdmsrl(u32 msr)
+static noinstr u64 mce_rdmsrl(u32 msr)
{
u64 v;

if (__this_cpu_read(injectm.finished)) {
- int offset = msr_to_offset(msr);
+ int offset;
+ u64 ret;

+ instrumentation_begin();
+
+ offset = msr_to_offset(msr);
if (offset < 0)
- return 0;
- return *(u64 *)((char *)this_cpu_ptr(&injectm) + offset);
+ ret = 0;
+ else
+ ret = *(u64 *)((char *)this_cpu_ptr(&injectm) + offset);
+
+ instrumentation_end();
+
+ return ret;
}

if (rdmsrl_safe(msr, &v)) {
@@ -399,13 +408,19 @@ static u64 mce_rdmsrl(u32 msr)
return v;
}

-static void mce_wrmsrl(u32 msr, u64 v)
+static noinstr void mce_wrmsrl(u32 msr, u64 v)
{
if (__this_cpu_read(injectm.finished)) {
- int offset = msr_to_offset(msr);
+ int offset;

+ instrumentation_begin();
+
+ offset = msr_to_offset(msr);
if (offset >= 0)
*(u64 *)((char *)this_cpu_ptr(&injectm) + offset) = v;
+
+ instrumentation_end();
+
return;
}
wrmsrl(msr, v);
--
2.25.1