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Subject[RFC 2/3] Allow saving of individual states in fpu_xsave().
Date
Add a feature mask argument to fpu_xsave(). Introduce XCNTXT_DEFAULT
to specify which feature states are to be saved/restored by default at
context switches. Rename XCNTXT_MASK to XCNTXT_SUPPORTED to make clear
what it really is.

Signed-off-by: Hans Rosenfeld <hans.rosenfeld@amd.com>
---
arch/x86/include/asm/i387.h | 4 ++--
arch/x86/include/asm/xsave.h | 14 +++++++++++---
arch/x86/kernel/xsave.c | 2 +-
3 files changed, 14 insertions(+), 6 deletions(-)
diff --git a/arch/x86/include/asm/i387.h b/arch/x86/include/asm/i387.h
index de8593b..33600d3 100644
--- a/arch/x86/include/asm/i387.h
+++ b/arch/x86/include/asm/i387.h
@@ -201,7 +201,7 @@ static inline void fpu_save_init(struct fpu *fpu)
if (use_xsave()) {
struct xsave_struct *xstate = &fpu->state->xsave;

- fpu_xsave(xstate);
+ fpu_xsave(xstate, XCNTXT_DEFAULT);

/*
* xsave header may indicate the init state of the FP.
@@ -239,7 +239,7 @@ static inline void __save_init_fpu(struct task_struct *tsk)
static inline int fpu_restore_checking(struct fpu *fpu)
{
if (use_xsave())
- return xrstor_checking(&fpu->state->xsave, -1);
+ return xrstor_checking(&fpu->state->xsave, XCNTXT_DEFAULT);
else
return fxrstor_checking(&fpu->state->fxsave);
}
diff --git a/arch/x86/include/asm/xsave.h b/arch/x86/include/asm/xsave.h
index 8bcbbce..8820b57 100644
--- a/arch/x86/include/asm/xsave.h
+++ b/arch/x86/include/asm/xsave.h
@@ -23,7 +23,12 @@
/*
* These are the features that the OS can handle currently.
*/
-#define XCNTXT_MASK (XSTATE_FP | XSTATE_SSE | XSTATE_YMM)
+#define XCNTXT_SUPPORTED (XSTATE_FP | XSTATE_SSE | XSTATE_YMM)
+
+/*
+ * These are the features that the OS saves/restores by default.
+ */
+#define XCNTXT_DEFAULT (-1)

#ifdef CONFIG_X86_64
#define REX_PREFIX "0x48, "
@@ -113,15 +118,18 @@ static inline void xsave_state(struct xsave_struct *fx, u64 mask)
: "memory");
}

-static inline void fpu_xsave(struct xsave_struct *fx)
+static inline void fpu_xsave(struct xsave_struct *fx, u64 mask)
{
+ u32 lmask = mask;
+ u32 hmask = mask >> 32;
+
/* This, however, we can work around by forcing the compiler to select
an addressing mode that doesn't require extended registers. */
alternative_input(
".byte " REX_PREFIX "0x0f,0xae,0x27",
".byte " REX_PREFIX "0x0f,0xae,0x37",
X86_FEATURE_XSAVEOPT,
- [fx] "D" (fx), "a" (-1), "d" (-1) :
+ [fx] "D" (fx), "a" (lmask), "d" (hmask) :
"memory");
}
#endif
diff --git a/arch/x86/kernel/xsave.c b/arch/x86/kernel/xsave.c
index 5eb15d4..11c3445 100644
--- a/arch/x86/kernel/xsave.c
+++ b/arch/x86/kernel/xsave.c
@@ -434,7 +434,7 @@ static void __init xstate_enable_boot_cpu(void)
/*
* Support only the state known to OS.
*/
- pcntxt_mask = pcntxt_mask & XCNTXT_MASK;
+ pcntxt_mask = pcntxt_mask & XCNTXT_SUPPORTED;

xstate_enable();

--
1.5.6.5



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