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authorLinus Torvalds <torvalds@linux-foundation.org>2020-06-02 00:09:26 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2020-06-02 00:09:26 +0300
commit0a319ef75d931de0b21882ec17d8d70ece0aa871 (patch)
tree80e9a3a5effe197646a30b0a016b5788bb778d3e /arch/x86
parenteff5ddadab04dc7ae8c4588dd3eef2ecad770fd7 (diff)
parent55e00fb66fd5048f4a3ee357018fd26fc527abca (diff)
downloadlinux-0a319ef75d931de0b21882ec17d8d70ece0aa871.tar.xz
Merge tag 'x86-fpu-2020-06-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 FPU updates from Ingo Molnar: "Most of the changes here related to 'XSAVES supervisor state' support, which is a feature that allows kernel-only data to be automatically saved/restored by the FPU context switching code. CPU features that can be supported this way are Intel PT, 'PASID' and CET features" * tag 'x86-fpu-2020-06-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/fpu/xstate: Restore supervisor states for signal return x86/fpu/xstate: Preserve supervisor states for the slow path in __fpu__restore_sig() x86/fpu: Introduce copy_supervisor_to_kernel() x86/fpu/xstate: Update copy_kernel_to_xregs_err() for supervisor states x86/fpu/xstate: Update sanitize_restored_xstate() for supervisor xstates x86/fpu/xstate: Define new functions for clearing fpregs and xstates x86/fpu/xstate: Introduce XSAVES supervisor states x86/fpu/xstate: Separate user and supervisor xfeatures mask x86/fpu/xstate: Define new macros for supervisor and user xstates x86/fpu/xstate: Rename validate_xstate_header() to validate_user_xstate_header()
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/include/asm/fpu/internal.h10
-rw-r--r--arch/x86/include/asm/fpu/xstate.h52
-rw-r--r--arch/x86/kernel/fpu/core.c53
-rw-r--r--arch/x86/kernel/fpu/init.c3
-rw-r--r--arch/x86/kernel/fpu/regset.c2
-rw-r--r--arch/x86/kernel/fpu/signal.c144
-rw-r--r--arch/x86/kernel/fpu/xstate.c199
-rw-r--r--arch/x86/kernel/process.c2
-rw-r--r--arch/x86/kernel/signal.c2
9 files changed, 336 insertions, 131 deletions
diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h
index 44c48e34d799..42159f45bf9c 100644
--- a/arch/x86/include/asm/fpu/internal.h
+++ b/arch/x86/include/asm/fpu/internal.h
@@ -31,7 +31,8 @@ extern void fpu__save(struct fpu *fpu);
extern int fpu__restore_sig(void __user *buf, int ia32_frame);
extern void fpu__drop(struct fpu *fpu);
extern int fpu__copy(struct task_struct *dst, struct task_struct *src);
-extern void fpu__clear(struct fpu *fpu);
+extern void fpu__clear_user_states(struct fpu *fpu);
+extern void fpu__clear_all(struct fpu *fpu);
extern int fpu__exception_code(struct fpu *fpu, int trap_nr);
extern int dump_fpu(struct pt_regs *ptregs, struct user_i387_struct *fpstate);
@@ -92,7 +93,7 @@ static inline void fpstate_init_xstate(struct xregs_state *xsave)
* XRSTORS requires these bits set in xcomp_bv, or it will
* trigger #GP:
*/
- xsave->header.xcomp_bv = XCOMP_BV_COMPACTED_FORMAT | xfeatures_mask;
+ xsave->header.xcomp_bv = XCOMP_BV_COMPACTED_FORMAT | xfeatures_mask_all;
}
static inline void fpstate_init_fxstate(struct fxregs_state *fx)
@@ -399,7 +400,10 @@ static inline int copy_kernel_to_xregs_err(struct xregs_state *xstate, u64 mask)
u32 hmask = mask >> 32;
int err;
- XSTATE_OP(XRSTOR, xstate, lmask, hmask, err);
+ if (static_cpu_has(X86_FEATURE_XSAVES))
+ XSTATE_OP(XRSTORS, xstate, lmask, hmask, err);
+ else
+ XSTATE_OP(XRSTOR, xstate, lmask, hmask, err);
return err;
}
diff --git a/arch/x86/include/asm/fpu/xstate.h b/arch/x86/include/asm/fpu/xstate.h
index c6136d79f8c0..422d8369012a 100644
--- a/arch/x86/include/asm/fpu/xstate.h
+++ b/arch/x86/include/asm/fpu/xstate.h
@@ -21,19 +21,29 @@
#define XSAVE_YMM_SIZE 256
#define XSAVE_YMM_OFFSET (XSAVE_HDR_SIZE + XSAVE_HDR_OFFSET)
-/* Supervisor features */
-#define XFEATURE_MASK_SUPERVISOR (XFEATURE_MASK_PT)
-
-/* All currently supported features */
-#define XCNTXT_MASK (XFEATURE_MASK_FP | \
- XFEATURE_MASK_SSE | \
- XFEATURE_MASK_YMM | \
- XFEATURE_MASK_OPMASK | \
- XFEATURE_MASK_ZMM_Hi256 | \
- XFEATURE_MASK_Hi16_ZMM | \
- XFEATURE_MASK_PKRU | \
- XFEATURE_MASK_BNDREGS | \
- XFEATURE_MASK_BNDCSR)
+/* All currently supported user features */
+#define XFEATURE_MASK_USER_SUPPORTED (XFEATURE_MASK_FP | \
+ XFEATURE_MASK_SSE | \
+ XFEATURE_MASK_YMM | \
+ XFEATURE_MASK_OPMASK | \
+ XFEATURE_MASK_ZMM_Hi256 | \
+ XFEATURE_MASK_Hi16_ZMM | \
+ XFEATURE_MASK_PKRU | \
+ XFEATURE_MASK_BNDREGS | \
+ XFEATURE_MASK_BNDCSR)
+
+/* All currently supported supervisor features */
+#define XFEATURE_MASK_SUPERVISOR_SUPPORTED (0)
+
+/*
+ * Unsupported supervisor features. When a supervisor feature in this mask is
+ * supported in the future, move it to the supported supervisor feature mask.
+ */
+#define XFEATURE_MASK_SUPERVISOR_UNSUPPORTED (XFEATURE_MASK_PT)
+
+/* All supervisor states including supported and unsupported states. */
+#define XFEATURE_MASK_SUPERVISOR_ALL (XFEATURE_MASK_SUPERVISOR_SUPPORTED | \
+ XFEATURE_MASK_SUPERVISOR_UNSUPPORTED)
#ifdef CONFIG_X86_64
#define REX_PREFIX "0x48, "
@@ -41,7 +51,18 @@
#define REX_PREFIX
#endif
-extern u64 xfeatures_mask;
+extern u64 xfeatures_mask_all;
+
+static inline u64 xfeatures_mask_supervisor(void)
+{
+ return xfeatures_mask_all & XFEATURE_MASK_SUPERVISOR_SUPPORTED;
+}
+
+static inline u64 xfeatures_mask_user(void)
+{
+ return xfeatures_mask_all & XFEATURE_MASK_USER_SUPPORTED;
+}
+
extern u64 xstate_fx_sw_bytes[USER_XSTATE_FX_SW_WORDS];
extern void __init update_regset_xstate_info(unsigned int size,
@@ -54,8 +75,9 @@ int copy_xstate_to_kernel(void *kbuf, struct xregs_state *xsave, unsigned int of
int copy_xstate_to_user(void __user *ubuf, struct xregs_state *xsave, unsigned int offset, unsigned int size);
int copy_kernel_to_xstate(struct xregs_state *xsave, const void *kbuf);
int copy_user_to_xstate(struct xregs_state *xsave, const void __user *ubuf);
+void copy_supervisor_to_kernel(struct xregs_state *xsave);
/* Validate an xstate header supplied by userspace (ptrace or sigreturn) */
-extern int validate_xstate_header(const struct xstate_header *hdr);
+int validate_user_xstate_header(const struct xstate_header *hdr);
#endif
diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index 12c70840980e..06c818967bb6 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -291,15 +291,13 @@ void fpu__drop(struct fpu *fpu)
}
/*
- * Clear FPU registers by setting them up from
- * the init fpstate:
+ * Clear FPU registers by setting them up from the init fpstate.
+ * Caller must do fpregs_[un]lock() around it.
*/
-static inline void copy_init_fpstate_to_fpregs(void)
+static inline void copy_init_fpstate_to_fpregs(u64 features_mask)
{
- fpregs_lock();
-
if (use_xsave())
- copy_kernel_to_xregs(&init_fpstate.xsave, -1);
+ copy_kernel_to_xregs(&init_fpstate.xsave, features_mask);
else if (static_cpu_has(X86_FEATURE_FXSR))
copy_kernel_to_fxregs(&init_fpstate.fxsave);
else
@@ -307,9 +305,6 @@ static inline void copy_init_fpstate_to_fpregs(void)
if (boot_cpu_has(X86_FEATURE_OSPKE))
copy_init_pkru_to_fpregs();
-
- fpregs_mark_activate();
- fpregs_unlock();
}
/*
@@ -318,18 +313,40 @@ static inline void copy_init_fpstate_to_fpregs(void)
* Called by sys_execve(), by the signal handler code and by various
* error paths.
*/
-void fpu__clear(struct fpu *fpu)
+static void fpu__clear(struct fpu *fpu, bool user_only)
{
- WARN_ON_FPU(fpu != &current->thread.fpu); /* Almost certainly an anomaly */
+ WARN_ON_FPU(fpu != &current->thread.fpu);
- fpu__drop(fpu);
+ if (!static_cpu_has(X86_FEATURE_FPU)) {
+ fpu__drop(fpu);
+ fpu__initialize(fpu);
+ return;
+ }
- /*
- * Make sure fpstate is cleared and initialized.
- */
- fpu__initialize(fpu);
- if (static_cpu_has(X86_FEATURE_FPU))
- copy_init_fpstate_to_fpregs();
+ fpregs_lock();
+
+ if (user_only) {
+ if (!fpregs_state_valid(fpu, smp_processor_id()) &&
+ xfeatures_mask_supervisor())
+ copy_kernel_to_xregs(&fpu->state.xsave,
+ xfeatures_mask_supervisor());
+ copy_init_fpstate_to_fpregs(xfeatures_mask_user());
+ } else {
+ copy_init_fpstate_to_fpregs(xfeatures_mask_all);
+ }
+
+ fpregs_mark_activate();
+ fpregs_unlock();
+}
+
+void fpu__clear_user_states(struct fpu *fpu)
+{
+ fpu__clear(fpu, true);
+}
+
+void fpu__clear_all(struct fpu *fpu)
+{
+ fpu__clear(fpu, false);
}
/*
diff --git a/arch/x86/kernel/fpu/init.c b/arch/x86/kernel/fpu/init.c
index 6ce7e0a23268..61ddc3a5e5c2 100644
--- a/arch/x86/kernel/fpu/init.c
+++ b/arch/x86/kernel/fpu/init.c
@@ -224,7 +224,8 @@ static void __init fpu__init_system_xstate_size_legacy(void)
*/
u64 __init fpu__get_supported_xfeatures_mask(void)
{
- return XCNTXT_MASK;
+ return XFEATURE_MASK_USER_SUPPORTED |
+ XFEATURE_MASK_SUPERVISOR_SUPPORTED;
}
/* Legacy code to initialize eager fpu mode. */
diff --git a/arch/x86/kernel/fpu/regset.c b/arch/x86/kernel/fpu/regset.c
index d652b939ccfb..bd1d0649f8ce 100644
--- a/arch/x86/kernel/fpu/regset.c
+++ b/arch/x86/kernel/fpu/regset.c
@@ -139,7 +139,7 @@ int xstateregs_set(struct task_struct *target, const struct user_regset *regset,
} else {
ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, xsave, 0, -1);
if (!ret)
- ret = validate_xstate_header(&xsave->header);
+ ret = validate_user_xstate_header(&xsave->header);
}
/*
diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c
index 400a05e1c1c5..9393a445d73c 100644
--- a/arch/x86/kernel/fpu/signal.c
+++ b/arch/x86/kernel/fpu/signal.c
@@ -211,9 +211,9 @@ retry:
}
static inline void
-sanitize_restored_xstate(union fpregs_state *state,
- struct user_i387_ia32_struct *ia32_env,
- u64 xfeatures, int fx_only)
+sanitize_restored_user_xstate(union fpregs_state *state,
+ struct user_i387_ia32_struct *ia32_env,
+ u64 user_xfeatures, int fx_only)
{
struct xregs_state *xsave = &state->xsave;
struct xstate_header *header = &xsave->header;
@@ -226,13 +226,22 @@ sanitize_restored_xstate(union fpregs_state *state,
*/
/*
- * Init the state that is not present in the memory
- * layout and not enabled by the OS.
+ * 'user_xfeatures' might have bits clear which are
+ * set in header->xfeatures. This represents features that
+ * were in init state prior to a signal delivery, and need
+ * to be reset back to the init state. Clear any user
+ * feature bits which are set in the kernel buffer to get
+ * them back to the init state.
+ *
+ * Supervisor state is unchanged by input from userspace.
+ * Ensure supervisor state bits stay set and supervisor
+ * state is not modified.
*/
if (fx_only)
header->xfeatures = XFEATURE_MASK_FPSSE;
else
- header->xfeatures &= xfeatures;
+ header->xfeatures &= user_xfeatures |
+ xfeatures_mask_supervisor();
}
if (use_fxsr()) {
@@ -252,16 +261,24 @@ sanitize_restored_xstate(union fpregs_state *state,
*/
static int copy_user_to_fpregs_zeroing(void __user *buf, u64 xbv, int fx_only)
{
+ u64 init_bv;
+ int r;
+
if (use_xsave()) {
if (fx_only) {
- u64 init_bv = xfeatures_mask & ~XFEATURE_MASK_FPSSE;
- copy_kernel_to_xregs(&init_fpstate.xsave, init_bv);
- return copy_user_to_fxregs(buf);
+ init_bv = xfeatures_mask_user() & ~XFEATURE_MASK_FPSSE;
+
+ r = copy_user_to_fxregs(buf);
+ if (!r)
+ copy_kernel_to_xregs(&init_fpstate.xsave, init_bv);
+ return r;
} else {
- u64 init_bv = xfeatures_mask & ~xbv;
- if (unlikely(init_bv))
+ init_bv = xfeatures_mask_user() & ~xbv;
+
+ r = copy_user_to_xregs(buf, xbv);
+ if (!r && unlikely(init_bv))
copy_kernel_to_xregs(&init_fpstate.xsave, init_bv);
- return copy_user_to_xregs(buf, xbv);
+ return r;
}
} else if (use_fxsr()) {
return copy_user_to_fxregs(buf);
@@ -277,7 +294,7 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
struct task_struct *tsk = current;
struct fpu *fpu = &tsk->thread.fpu;
struct user_i387_ia32_struct env;
- u64 xfeatures = 0;
+ u64 user_xfeatures = 0;
int fx_only = 0;
int ret = 0;
@@ -285,7 +302,7 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
IS_ENABLED(CONFIG_IA32_EMULATION));
if (!buf) {
- fpu__clear(fpu);
+ fpu__clear_user_states(fpu);
return 0;
}
@@ -310,32 +327,14 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
trace_x86_fpu_xstate_check_failed(fpu);
} else {
state_size = fx_sw_user.xstate_size;
- xfeatures = fx_sw_user.xfeatures;
+ user_xfeatures = fx_sw_user.xfeatures;
}
}
- /*
- * The current state of the FPU registers does not matter. By setting
- * TIF_NEED_FPU_LOAD unconditionally it is ensured that the our xstate
- * is not modified on context switch and that the xstate is considered
- * to be loaded again on return to userland (overriding last_cpu avoids
- * the optimisation).
- */
- set_thread_flag(TIF_NEED_FPU_LOAD);
- __fpu_invalidate_fpregs_state(fpu);
-
if ((unsigned long)buf_fx % 64)
fx_only = 1;
- /*
- * For 32-bit frames with fxstate, copy the fxstate so it can be
- * reconstructed later.
- */
- if (ia32_fxstate) {
- ret = __copy_from_user(&env, buf, sizeof(env));
- if (ret)
- goto err_out;
- envp = &env;
- } else {
+
+ if (!ia32_fxstate) {
/*
* Attempt to restore the FPU registers directly from user
* memory. For that to succeed, the user access cannot cause
@@ -345,20 +344,65 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
*/
fpregs_lock();
pagefault_disable();
- ret = copy_user_to_fpregs_zeroing(buf_fx, xfeatures, fx_only);
+ ret = copy_user_to_fpregs_zeroing(buf_fx, user_xfeatures, fx_only);
pagefault_enable();
if (!ret) {
+
+ /*
+ * Restore supervisor states: previous context switch
+ * etc has done XSAVES and saved the supervisor states
+ * in the kernel buffer from which they can be restored
+ * now.
+ *
+ * We cannot do a single XRSTORS here - which would
+ * be nice - because the rest of the FPU registers are
+ * being restored from a user buffer directly. The
+ * single XRSTORS happens below, when the user buffer
+ * has been copied to the kernel one.
+ */
+ if (test_thread_flag(TIF_NEED_FPU_LOAD) &&
+ xfeatures_mask_supervisor())
+ copy_kernel_to_xregs(&fpu->state.xsave,
+ xfeatures_mask_supervisor());
fpregs_mark_activate();
fpregs_unlock();
return 0;
}
- fpregs_deactivate(fpu);
fpregs_unlock();
+ } else {
+ /*
+ * For 32-bit frames with fxstate, copy the fxstate so it can
+ * be reconstructed later.
+ */
+ ret = __copy_from_user(&env, buf, sizeof(env));
+ if (ret)
+ goto err_out;
+ envp = &env;
}
+ /*
+ * By setting TIF_NEED_FPU_LOAD it is ensured that our xstate is
+ * not modified on context switch and that the xstate is considered
+ * to be loaded again on return to userland (overriding last_cpu avoids
+ * the optimisation).
+ */
+ fpregs_lock();
+
+ if (!test_thread_flag(TIF_NEED_FPU_LOAD)) {
+
+ /*
+ * Supervisor states are not modified by user space input. Save
+ * current supervisor states first and invalidate the FPU regs.
+ */
+ if (xfeatures_mask_supervisor())
+ copy_supervisor_to_kernel(&fpu->state.xsave);
+ set_thread_flag(TIF_NEED_FPU_LOAD);
+ }
+ __fpu_invalidate_fpregs_state(fpu);
+ fpregs_unlock();
if (use_xsave() && !fx_only) {
- u64 init_bv = xfeatures_mask & ~xfeatures;
+ u64 init_bv = xfeatures_mask_user() & ~user_xfeatures;
if (using_compacted_format()) {
ret = copy_user_to_xstate(&fpu->state.xsave, buf_fx);
@@ -366,17 +410,24 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
ret = __copy_from_user(&fpu->state.xsave, buf_fx, state_size);
if (!ret && state_size > offsetof(struct xregs_state, header))
- ret = validate_xstate_header(&fpu->state.xsave.header);
+ ret = validate_user_xstate_header(&fpu->state.xsave.header);
}
if (ret)
goto err_out;
- sanitize_restored_xstate(&fpu->state, envp, xfeatures, fx_only);
+ sanitize_restored_user_xstate(&fpu->state, envp, user_xfeatures,
+ fx_only);
fpregs_lock();
if (unlikely(init_bv))
copy_kernel_to_xregs(&init_fpstate.xsave, init_bv);
- ret = copy_kernel_to_xregs_err(&fpu->state.xsave, xfeatures);
+
+ /*
+ * Restore previously saved supervisor xstates along with
+ * copied-in user xstates.
+ */
+ ret = copy_kernel_to_xregs_err(&fpu->state.xsave,
+ user_xfeatures | xfeatures_mask_supervisor());
} else if (use_fxsr()) {
ret = __copy_from_user(&fpu->state.fxsave, buf_fx, state_size);
@@ -385,11 +436,14 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
goto err_out;
}
- sanitize_restored_xstate(&fpu->state, envp, xfeatures, fx_only);
+ sanitize_restored_user_xstate(&fpu->state, envp, user_xfeatures,
+ fx_only);
fpregs_lock();
if (use_xsave()) {
- u64 init_bv = xfeatures_mask & ~XFEATURE_MASK_FPSSE;
+ u64 init_bv;
+
+ init_bv = xfeatures_mask_user() & ~XFEATURE_MASK_FPSSE;
copy_kernel_to_xregs(&init_fpstate.xsave, init_bv);
}
@@ -410,7 +464,7 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
err_out:
if (ret)
- fpu__clear(fpu);
+ fpu__clear_user_states(fpu);
return ret;
}
@@ -465,7 +519,7 @@ void fpu__init_prepare_fx_sw_frame(void)
fx_sw_reserved.magic1 = FP_XSTATE_MAGIC1;
fx_sw_reserved.extended_size = size;
- fx_sw_reserved.xfeatures = xfeatures_mask;
+ fx_sw_reserved.xfeatures = xfeatures_mask_user();
fx_sw_reserved.xstate_size = fpu_user_xstate_size;
if (IS_ENABLED(CONFIG_IA32_EMULATION) ||
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index 6a54e83d5589..bda2e5eaca0e 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -54,13 +54,15 @@ static short xsave_cpuid_features[] __initdata = {
};
/*
- * Mask of xstate features supported by the CPU and the kernel:
+ * This represents the full set of bits that should ever be set in a kernel
+ * XSAVE buffer, both supervisor and user xstates.
*/
-u64 xfeatures_mask __read_mostly;
+u64 xfeatures_mask_all __read_mostly;
static unsigned int xstate_offsets[XFEATURE_MAX] = { [ 0 ... XFEATURE_MAX - 1] = -1};
static unsigned int xstate_sizes[XFEATURE_MAX] = { [ 0 ... XFEATURE_MAX - 1] = -1};
static unsigned int xstate_comp_offsets[XFEATURE_MAX] = { [ 0 ... XFEATURE_MAX - 1] = -1};
+static unsigned int xstate_supervisor_only_offsets[XFEATURE_MAX] = { [ 0 ... XFEATURE_MAX - 1] = -1};
/*
* The XSAVE area of kernel can be in standard or compacted format;
@@ -76,7 +78,7 @@ unsigned int fpu_user_xstate_size;
*/
int cpu_has_xfeatures(u64 xfeatures_needed, const char **feature_name)
{
- u64 xfeatures_missing = xfeatures_needed & ~xfeatures_mask;
+ u64 xfeatures_missing = xfeatures_needed & ~xfeatures_mask_all;
if (unlikely(feature_name)) {
long xfeature_idx, max_idx;
@@ -150,7 +152,7 @@ void fpstate_sanitize_xstate(struct fpu *fpu)
* None of the feature bits are in init state. So nothing else
* to do for us, as the memory layout is up to date.
*/
- if ((xfeatures & xfeatures_mask) == xfeatures_mask)
+ if ((xfeatures & xfeatures_mask_all) == xfeatures_mask_all)
return;
/*
@@ -177,7 +179,7 @@ void fpstate_sanitize_xstate(struct fpu *fpu)
* in a special way already:
*/
feature_bit = 0x2;
- xfeatures = (xfeatures_mask & ~xfeatures) >> 2;
+ xfeatures = (xfeatures_mask_user() & ~xfeatures) >> 2;
/*
* Update all the remaining memory layouts according to their
@@ -205,30 +207,39 @@ void fpstate_sanitize_xstate(struct fpu *fpu)
*/
void fpu__init_cpu_xstate(void)
{
- if (!boot_cpu_has(X86_FEATURE_XSAVE) || !xfeatures_mask)
+ u64 unsup_bits;
+
+ if (!boot_cpu_has(X86_FEATURE_XSAVE) || !xfeatures_mask_all)
return;
/*
- * Make it clear that XSAVES supervisor states are not yet
- * implemented should anyone expect it to work by changing
- * bits in XFEATURE_MASK_* macros and XCR0.
+ * Unsupported supervisor xstates should not be found in
+ * the xfeatures mask.
*/
- WARN_ONCE((xfeatures_mask & XFEATURE_MASK_SUPERVISOR),
- "x86/fpu: XSAVES supervisor states are not yet implemented.\n");
+ unsup_bits = xfeatures_mask_all & XFEATURE_MASK_SUPERVISOR_UNSUPPORTED;
+ WARN_ONCE(unsup_bits, "x86/fpu: Found unsupported supervisor xstates: 0x%llx\n",
+ unsup_bits);
- xfeatures_mask &= ~XFEATURE_MASK_SUPERVISOR;
+ xfeatures_mask_all &= ~XFEATURE_MASK_SUPERVISOR_UNSUPPORTED;
cr4_set_bits(X86_CR4_OSXSAVE);
- xsetbv(XCR_XFEATURE_ENABLED_MASK, xfeatures_mask);
+
+ /*
+ * XCR_XFEATURE_ENABLED_MASK (aka. XCR0) sets user features
+ * managed by XSAVE{C, OPT, S} and XRSTOR{S}. Only XSAVE user
+ * states can be set here.
+ */
+ xsetbv(XCR_XFEATURE_ENABLED_MASK, xfeatures_mask_user());
+
+ /*
+ * MSR_IA32_XSS sets supervisor states managed by XSAVES.
+ */
+ if (boot_cpu_has(X86_FEATURE_XSAVES))
+ wrmsrl(MSR_IA32_XSS, xfeatures_mask_supervisor());
}
-/*
- * Note that in the future we will likely need a pair of
- * functions here: one for user xstates and the other for
- * system xstates. For now, they are the same.
- */
-static int xfeature_enabled(enum xfeature xfeature)
+static bool xfeature_enabled(enum xfeature xfeature)
{
- return !!(xfeatures_mask & (1UL << xfeature));
+ return xfeatures_mask_all & BIT_ULL(xfeature);
}
/*
@@ -383,6 +394,33 @@ static void __init setup_xstate_comp_offsets(void)
}
/*
+ * Setup offsets of a supervisor-state-only XSAVES buffer:
+ *
+ * The offsets stored in xstate_comp_offsets[] only work for one specific
+ * value of the Requested Feature BitMap (RFBM). In cases where a different
+ * RFBM value is used, a different set of offsets is required. This set of
+ * offsets is for when RFBM=xfeatures_mask_supervisor().
+ */
+static void __init setup_supervisor_only_offsets(void)
+{
+ unsigned int next_offset;
+ int i;
+
+ next_offset = FXSAVE_SIZE + XSAVE_HDR_SIZE;
+
+ for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
+ if (!xfeature_enabled(i) || !xfeature_is_supervisor(i))
+ continue;
+
+ if (xfeature_is_aligned(i))
+ next_offset = ALIGN(next_offset, 64);
+
+ xstate_supervisor_only_offsets[i] = next_offset;
+ next_offset += xstate_sizes[i];
+ }
+}
+
+/*
* Print out xstate component offsets and sizes
*/
static void __init print_xstate_offset_size(void)
@@ -415,7 +453,7 @@ static void __init setup_init_fpu_buf(void)
if (boot_cpu_has(X86_FEATURE_XSAVES))
init_fpstate.xsave.header.xcomp_bv = XCOMP_BV_COMPACTED_FORMAT |
- xfeatures_mask;
+ xfeatures_mask_all;
/*
* Init all the features state with header.xfeatures being 0x0
@@ -438,7 +476,7 @@ static int xfeature_uncompacted_offset(int xfeature_nr)
* format. Checking a supervisor state's uncompacted offset is
* an error.
*/
- if (XFEATURE_MASK_SUPERVISOR & BIT_ULL(xfeature_nr)) {
+ if (XFEATURE_MASK_SUPERVISOR_ALL & BIT_ULL(xfeature_nr)) {
WARN_ONCE(1, "No fixed offset for xstate %d\n", xfeature_nr);
return -1;
}
@@ -472,10 +510,10 @@ int using_compacted_format(void)
}
/* Validate an xstate header supplied by userspace (ptrace or sigreturn) */
-int validate_xstate_header(const struct xstate_header *hdr)
+int validate_user_xstate_header(const struct xstate_header *hdr)
{
/* No unknown or supervisor features may be set */
- if (hdr->xfeatures & (~xfeatures_mask | XFEATURE_MASK_SUPERVISOR))
+ if (hdr->xfeatures & ~xfeatures_mask_user())
return -EINVAL;
/* Userspace must use the uncompacted format */
@@ -610,15 +648,12 @@ static void do_extra_xstate_size_checks(void)
/*
- * Get total size of enabled xstates in XCR0/xfeatures_mask.
+ * Get total size of enabled xstates in XCR0 | IA32_XSS.
*
* Note the SDM's wording here. "sub-function 0" only enumerates
* the size of the *user* states. If we use it to size a buffer
* that we use 'XSAVES' on, we could potentially overflow the
* buffer because 'XSAVES' saves system states too.
- *
- * Note that we do not currently set any bits on IA32_XSS so
- * 'XCR0 | IA32_XSS == XCR0' for now.
*/
static unsigned int __init get_xsaves_size(void)
{
@@ -700,7 +735,7 @@ static int __init init_xstate_size(void)
*/
static void fpu__init_disable_system_xstate(void)
{
- xfeatures_mask = 0;
+ xfeatures_mask_all = 0;
cr4_clear_bits(X86_CR4_OSXSAVE);
setup_clear_cpu_cap(X86_FEATURE_XSAVE);
}
@@ -735,16 +770,26 @@ void __init fpu__init_system_xstate(void)
return;
}
+ /*
+ * Find user xstates supported by the processor.
+ */
cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx);
- xfeatures_mask = eax + ((u64)edx << 32);
+ xfeatures_mask_all = eax + ((u64)edx << 32);
- if ((xfeatures_mask & XFEATURE_MASK_FPSSE) != XFEATURE_MASK_FPSSE) {
+ /*
+ * Find supervisor xstates supported by the processor.
+ */
+ cpuid_count(XSTATE_CPUID, 1, &eax, &ebx, &ecx, &edx);
+ xfeatures_mask_all |= ecx + ((u64)edx << 32);
+
+ if ((xfeatures_mask_user() & XFEATURE_MASK_FPSSE) != XFEATURE_MASK_FPSSE) {
/*
* This indicates that something really unexpected happened
* with the enumeration. Disable XSAVE and try to continue
* booting without it. This is too early to BUG().
*/
- pr_err("x86/fpu: FP/SSE not present amongst the CPU's xstate features: 0x%llx.\n", xfeatures_mask);
+ pr_err("x86/fpu: FP/SSE not present amongst the CPU's xstate features: 0x%llx.\n",
+ xfeatures_mask_all);
goto out_disable;
}
@@ -753,10 +798,10 @@ void __init fpu__init_system_xstate(void)
*/
for (i = 0; i < ARRAY_SIZE(xsave_cpuid_features); i++) {
if (!boot_cpu_has(xsave_cpuid_features[i]))
- xfeatures_mask &= ~BIT(i);
+ xfeatures_mask_all &= ~BIT_ULL(i);
}
- xfeatures_mask &= fpu__get_supported_xfeatures_mask();
+ xfeatures_mask_all &= fpu__get_supported_xfeatures_mask();
/* Enable xstate instructions to be able to continue with initialization: */
fpu__init_cpu_xstate();
@@ -768,15 +813,16 @@ void __init fpu__init_system_xstate(void)
* Update info used for ptrace frames; use standard-format size and no
* supervisor xstates:
*/
- update_regset_xstate_info(fpu_user_xstate_size, xfeatures_mask & ~XFEATURE_MASK_SUPERVISOR);
+ update_regset_xstate_info(fpu_user_xstate_size, xfeatures_mask_user());
fpu__init_prepare_fx_sw_frame();
setup_init_fpu_buf();
setup_xstate_comp_offsets();
+ setup_supervisor_only_offsets();
print_xstate_offset_size();
pr_info("x86/fpu: Enabled xstate features 0x%llx, context size is %d bytes, using '%s' format.\n",
- xfeatures_mask,
+ xfeatures_mask_all,
fpu_kernel_xstate_size,
boot_cpu_has(X86_FEATURE_XSAVES) ? "compacted" : "standard");
return;
@@ -795,7 +841,14 @@ void fpu__resume_cpu(void)
* Restore XCR0 on xsave capable CPUs:
*/
if (boot_cpu_has(X86_FEATURE_XSAVE))
- xsetbv(XCR_XFEATURE_ENABLED_MASK, xfeatures_mask);
+ xsetbv(XCR_XFEATURE_ENABLED_MASK, xfeatures_mask_user());
+
+ /*
+ * Restore IA32_XSS. The same CPUID bit enumerates support
+ * of XSAVES and MSR_IA32_XSS.
+ */
+ if (boot_cpu_has(X86_FEATURE_XSAVES))
+ wrmsrl(MSR_IA32_XSS, xfeatures_mask_supervisor());
}
/*
@@ -840,10 +893,9 @@ void *get_xsave_addr(struct xregs_state *xsave, int xfeature_nr)
/*
* We should not ever be requesting features that we
- * have not enabled. Remember that xfeatures_mask is
- * what we write to the XCR0 register.
+ * have not enabled.
*/
- WARN_ONCE(!(xfeatures_mask & BIT_ULL(xfeature_nr)),
+ WARN_ONCE(!(xfeatures_mask_all & BIT_ULL(xfeature_nr)),
"get of unsupported state");
/*
* This assumes the last 'xsave*' instruction to
@@ -1010,7 +1062,7 @@ int copy_xstate_to_kernel(void *kbuf, struct xregs_state *xsave, unsigned int of
*/
memset(&header, 0, sizeof(header));
header.xfeatures = xsave->header.xfeatures;
- header.xfeatures &= ~XFEATURE_MASK_SUPERVISOR;
+ header.xfeatures &= xfeatures_mask_user();
if (header.xfeatures & XFEATURE_MASK_FP)
copy_part(0, off_mxcsr,
@@ -1090,7 +1142,7 @@ int copy_xstate_to_user(void __user *ubuf, struct xregs_state *xsave, unsigned i
*/
memset(&header, 0, sizeof(header));
header.xfeatures = xsave->header.xfeatures;
- header.xfeatures &= ~XFEATURE_MASK_SUPERVISOR;
+ header.xfeatures &= xfeatures_mask_user();
/*
* Copy xregs_state->header:
@@ -1157,7 +1209,7 @@ int copy_kernel_to_xstate(struct xregs_state *xsave, const void *kbuf)
memcpy(&hdr, kbuf + offset, size);
- if (validate_xstate_header(&hdr))
+ if (validate_user_xstate_header(&hdr))
return -EINVAL;
for (i = 0; i < XFEATURE_MAX; i++) {
@@ -1183,7 +1235,7 @@ int copy_kernel_to_xstate(struct xregs_state *xsave, const void *kbuf)
* The state that came in from userspace was user-state only.
* Mask all the user states out of 'xfeatures':
*/
- xsave->header.xfeatures &= XFEATURE_MASK_SUPERVISOR;
+ xsave->header.xfeatures &= XFEATURE_MASK_SUPERVISOR_ALL;
/*
* Add back in the features that came in from userspace:
@@ -1211,7 +1263,7 @@ int copy_user_to_xstate(struct xregs_state *xsave, const void __user *ubuf)
if (__copy_from_user(&hdr, ubuf + offset, size))
return -EFAULT;
- if (validate_xstate_header(&hdr))
+ if (validate_user_xstate_header(&hdr))
return -EINVAL;
for (i = 0; i < XFEATURE_MAX; i++) {
@@ -1239,7 +1291,7 @@ int copy_user_to_xstate(struct xregs_state *xsave, const void __user *ubuf)
* The state that came in from userspace was user-state only.
* Mask all the user states out of 'xfeatures':
*/
- xsave->header.xfeatures &= XFEATURE_MASK_SUPERVISOR;
+ xsave->header.xfeatures &= XFEATURE_MASK_SUPERVISOR_ALL;
/*
* Add back in the features that came in from userspace:
@@ -1249,6 +1301,61 @@ int copy_user_to_xstate(struct xregs_state *xsave, const void __user *ubuf)
return 0;
}
+/*
+ * Save only supervisor states to the kernel buffer. This blows away all
+ * old states, and is intended to be used only in __fpu__restore_sig(), where
+ * user states are restored from the user buffer.
+ */
+void copy_supervisor_to_kernel(struct xregs_state *xstate)
+{
+ struct xstate_header *header;
+ u64 max_bit, min_bit;
+ u32 lmask, hmask;
+ int err, i;
+
+ if (WARN_ON(!boot_cpu_has(X86_FEATURE_XSAVES)))
+ return;
+
+ if (!xfeatures_mask_supervisor())
+ return;
+
+ max_bit = __fls(xfeatures_mask_supervisor());
+ min_bit = __ffs(xfeatures_mask_supervisor());
+
+ lmask = xfeatures_mask_supervisor();
+ hmask = xfeatures_mask_supervisor() >> 32;
+ XSTATE_OP(XSAVES, xstate, lmask, hmask, err);
+
+ /* We should never fault when copying to a kernel buffer: */
+ if (WARN_ON_FPU(err))
+ return;
+
+ /*
+ * At this point, the buffer has only supervisor states and must be
+ * converted back to normal kernel format.
+ */
+ header = &xstate->header;
+ header->xcomp_bv |= xfeatures_mask_all;
+
+ /*
+ * This only moves states up in the buffer. Start with
+ * the last state and move backwards so that states are
+ * not overwritten until after they are moved. Note:
+ * memmove() allows overlapping src/dst buffers.
+ */
+ for (i = max_bit; i >= min_bit; i--) {
+ u8 *xbuf = (u8 *)xstate;
+
+ if (!((header->xfeatures >> i) & 1))
+ continue;
+
+ /* Move xfeature 'i' into its normal location */
+ memmove(xbuf + xstate_comp_offsets[i],
+ xbuf + xstate_supervisor_only_offsets[i],
+ xstate_sizes[i]);
+ }
+}
+
#ifdef CONFIG_PROC_PID_ARCH_STATUS
/*
* Report the amount of time elapsed in millisecond since last AVX512
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 35638f1c5791..ce6cd220f722 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -191,7 +191,7 @@ void flush_thread(void)
flush_ptrace_hw_breakpoint(tsk);
memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array));
- fpu__clear(&tsk->thread.fpu);
+ fpu__clear_all(&tsk->thread.fpu);
}
void disable_TSC(void)
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index 83b74fb38c8f..0052bbe5dfd4 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -732,7 +732,7 @@ handle_signal(struct ksignal *ksig, struct pt_regs *regs)
/*
* Ensure the signal handler starts with the new fpu state.
*/
- fpu__clear(fpu);
+ fpu__clear_user_states(fpu);
}
signal_setup_done(failed, ksig, stepping);
}