The following commit has been merged into the x86/fpu branch of tip:
Commit-ID: 1d9bffab116fadfe1594f5fea2b50ab280d81d30
Gitweb: https://git.kernel.org/tip/1d9bffab116fadfe1594f5fea2b50ab280d81d30
Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
AuthorDate: Wed, 23 Jun 2021 14:02:15 +02:00
Committer: Borislav Petkov <bp@xxxxxxx>
CommitterDate: Wed, 23 Jun 2021 19:26:37 +02:00
x86/fpu: Move FXSAVE_LEAK quirk info __copy_kernel_to_fpregs()
copy_kernel_to_fpregs() restores all xfeatures but it is also the place
where the AMD FXSAVE_LEAK bug is handled.
That prevents fpregs_restore_userregs() to limit the restored features,
which is required to untangle PKRU and XSTATE handling and also for the
upcoming supervisor state management.
Move the FXSAVE_LEAK quirk into __copy_kernel_to_fpregs() and deinline that
function which has become rather fat.
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Reviewed-by: Borislav Petkov <bp@xxxxxxx>
Link: https://lkml.kernel.org/r/20210623121456.114271278@xxxxxxxxxxxxx
---
arch/x86/include/asm/fpu/internal.h | 25 +------------------------
arch/x86/kernel/fpu/core.c | 27 +++++++++++++++++++++++++++
2 files changed, 28 insertions(+), 24 deletions(-)
diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h
index f7688f6..63d9796 100644
--- a/arch/x86/include/asm/fpu/internal.h
+++ b/arch/x86/include/asm/fpu/internal.h
@@ -379,33 +379,10 @@ static inline int os_xrstor_safe(struct xregs_state *xstate, u64 mask)
return err;
}
-static inline void __restore_fpregs_from_fpstate(union fpregs_state *fpstate, u64 mask)
-{
- if (use_xsave()) {
- os_xrstor(&fpstate->xsave, mask);
- } else {
- if (use_fxsr())
- fxrstor(&fpstate->fxsave);
- else
- frstor(&fpstate->fsave);
- }
-}
+extern void __restore_fpregs_from_fpstate(union fpregs_state *fpstate, u64 mask);
static inline void restore_fpregs_from_fpstate(union fpregs_state *fpstate)
{
- /*
- * AMD K7/K8 CPUs don't save/restore FDP/FIP/FOP unless an exception is
- * pending. Clear the x87 state here by setting it to fixed values.
- * "m" is a random variable that should be in L1.
- */
- if (unlikely(static_cpu_has_bug(X86_BUG_FXSAVE_LEAK))) {
- asm volatile(
- "fnclex\n\t"
- "emms\n\t"
- "fildl %P[addr]" /* set F?P to defined value */
- : : [addr] "m" (fpstate));
- }
-
__restore_fpregs_from_fpstate(fpstate, -1);
}
diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index 6babf18..afd0dee 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -124,6 +124,33 @@ void save_fpregs_to_fpstate(struct fpu *fpu)
}
EXPORT_SYMBOL(save_fpregs_to_fpstate);
+void __restore_fpregs_from_fpstate(union fpregs_state *fpstate, u64 mask)
+{
+ /*
+ * AMD K7/K8 and later CPUs up to Zen don't save/restore
+ * FDP/FIP/FOP unless an exception is pending. Clear the x87 state
+ * here by setting it to fixed values. "m" is a random variable
+ * that should be in L1.
+ */
+ if (unlikely(static_cpu_has_bug(X86_BUG_FXSAVE_LEAK))) {
+ asm volatile(
+ "fnclex\n\t"
+ "emms\n\t"
+ "fildl %P[addr]" /* set F?P to defined value */
+ : : [addr] "m" (fpstate));
+ }
+
+ if (use_xsave()) {
+ os_xrstor(&fpstate->xsave, mask);
+ } else {
+ if (use_fxsr())
+ fxrstor(&fpstate->fxsave);
+ else
+ frstor(&fpstate->fsave);
+ }
+}
+EXPORT_SYMBOL_GPL(__restore_fpregs_from_fpstate);
+
void kernel_fpu_begin_mask(unsigned int kfpu_mask)
{
preempt_disable();
|