[PATCH] x86/fsgsbase: Replace static_cpu_has() with boot_cpu_has()

From: Borislav Petkov
Date: Tue Aug 18 2020 - 06:36:39 EST


From: Borislav Petkov <bp@xxxxxxx>

ptrace and prctl() are not really fast paths to warrant the use of
static_cpu_has() and cause alternatives patching for no good reason.
Replace with boot_cpu_has() which is simple and fast enough.

No functional changes.

Signed-off-by: Borislav Petkov <bp@xxxxxxx>
---
arch/x86/include/asm/fsgsbase.h | 4 ++--
arch/x86/kernel/process_64.c | 8 ++++----
2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/x86/include/asm/fsgsbase.h b/arch/x86/include/asm/fsgsbase.h
index d552646411a9..35cff5f2becf 100644
--- a/arch/x86/include/asm/fsgsbase.h
+++ b/arch/x86/include/asm/fsgsbase.h
@@ -57,7 +57,7 @@ static inline unsigned long x86_fsbase_read_cpu(void)
{
unsigned long fsbase;

- if (static_cpu_has(X86_FEATURE_FSGSBASE))
+ if (boot_cpu_has(X86_FEATURE_FSGSBASE))
fsbase = rdfsbase();
else
rdmsrl(MSR_FS_BASE, fsbase);
@@ -67,7 +67,7 @@ static inline unsigned long x86_fsbase_read_cpu(void)

static inline void x86_fsbase_write_cpu(unsigned long fsbase)
{
- if (static_cpu_has(X86_FEATURE_FSGSBASE))
+ if (boot_cpu_has(X86_FEATURE_FSGSBASE))
wrfsbase(fsbase);
else
wrmsrl(MSR_FS_BASE, fsbase);
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 9afefe325acb..df342bedea88 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -407,7 +407,7 @@ unsigned long x86_gsbase_read_cpu_inactive(void)
{
unsigned long gsbase;

- if (static_cpu_has(X86_FEATURE_FSGSBASE)) {
+ if (boot_cpu_has(X86_FEATURE_FSGSBASE)) {
unsigned long flags;

local_irq_save(flags);
@@ -422,7 +422,7 @@ unsigned long x86_gsbase_read_cpu_inactive(void)

void x86_gsbase_write_cpu_inactive(unsigned long gsbase)
{
- if (static_cpu_has(X86_FEATURE_FSGSBASE)) {
+ if (boot_cpu_has(X86_FEATURE_FSGSBASE)) {
unsigned long flags;

local_irq_save(flags);
@@ -439,7 +439,7 @@ unsigned long x86_fsbase_read_task(struct task_struct *task)

if (task == current)
fsbase = x86_fsbase_read_cpu();
- else if (static_cpu_has(X86_FEATURE_FSGSBASE) ||
+ else if (boot_cpu_has(X86_FEATURE_FSGSBASE) ||
(task->thread.fsindex == 0))
fsbase = task->thread.fsbase;
else
@@ -454,7 +454,7 @@ unsigned long x86_gsbase_read_task(struct task_struct *task)

if (task == current)
gsbase = x86_gsbase_read_cpu_inactive();
- else if (static_cpu_has(X86_FEATURE_FSGSBASE) ||
+ else if (boot_cpu_has(X86_FEATURE_FSGSBASE) ||
(task->thread.gsindex == 0))
gsbase = task->thread.gsbase;
else
--
2.21.0