summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
Diffstat
-rw-r--r--arch/x86/include/asm/fpu-internal.h96
-rw-r--r--arch/x86/include/asm/i387.h1
-rw-r--r--arch/x86/include/asm/xsave.h1
-rw-r--r--arch/x86/kernel/cpu/bugs.c7
-rw-r--r--arch/x86/kernel/i387.c20
-rw-r--r--arch/x86/kernel/process.c12
-rw-r--r--arch/x86/kernel/process_32.c4
-rw-r--r--arch/x86/kernel/process_64.c4
-rw-r--r--arch/x86/kernel/traps.c5
-rw-r--r--arch/x86/kernel/xsave.c57
10 files changed, 146 insertions, 61 deletions
diff --git a/arch/x86/include/asm/fpu-internal.h b/arch/x86/include/asm/fpu-internal.h
index 52202a6..8ca0f9f 100644
--- a/arch/x86/include/asm/fpu-internal.h
+++ b/arch/x86/include/asm/fpu-internal.h
@@ -291,15 +291,48 @@ static inline void __thread_set_has_fpu(struct task_struct *tsk)
static inline void __thread_fpu_end(struct task_struct *tsk)
{
__thread_clear_has_fpu(tsk);
- stts();
+ if (!use_xsave())
+ stts();
}
static inline void __thread_fpu_begin(struct task_struct *tsk)
{
- clts();
+ if (!use_xsave())
+ clts();
__thread_set_has_fpu(tsk);
}
+static inline void __drop_fpu(struct task_struct *tsk)
+{
+ if (__thread_has_fpu(tsk)) {
+ /* Ignore delayed exceptions from user space */
+ asm volatile("1: fwait\n"
+ "2:\n"
+ _ASM_EXTABLE(1b, 2b));
+ __thread_fpu_end(tsk);
+ }
+}
+
+static inline void drop_fpu(struct task_struct *tsk)
+{
+ /*
+ * Forget coprocessor state..
+ */
+ preempt_disable();
+ tsk->fpu_counter = 0;
+ __drop_fpu(tsk);
+ clear_used_math();
+ preempt_enable();
+}
+
+static inline void drop_init_fpu(struct task_struct *tsk)
+{
+ if (!use_xsave())
+ drop_fpu(tsk);
+ else
+ xrstor_state(init_xstate_buf, -1);
+}
+
/*
* FPU state switching for scheduling.
*
@@ -333,7 +366,12 @@ static inline fpu_switch_t switch_fpu_prepare(struct task_struct *old, struct ta
{
fpu_switch_t fpu;
- fpu.preload = tsk_used_math(new) && new->fpu_counter > 5;
+ /*
+ * If the task has used the math, pre-load the FPU on xsave processors
+ * or if the past 5 consecutive context-switches used math.
+ */
+ fpu.preload = tsk_used_math(new) && (use_xsave() ||
+ new->fpu_counter > 5);
if (__thread_has_fpu(old)) {
if (!__save_init_fpu(old))
cpu = ~0;
@@ -345,14 +383,14 @@ static inline fpu_switch_t switch_fpu_prepare(struct task_struct *old, struct ta
new->fpu_counter++;
__thread_set_has_fpu(new);
prefetch(new->thread.fpu.state);
- } else
+ } else if (!use_xsave())
stts();
} else {
old->fpu_counter = 0;
old->thread.fpu.last_cpu = ~0;
if (fpu.preload) {
new->fpu_counter++;
- if (fpu_lazy_restore(new, cpu))
+ if (!use_xsave() && fpu_lazy_restore(new, cpu))
fpu.preload = 0;
else
prefetch(new->thread.fpu.state);
@@ -372,7 +410,7 @@ static inline void switch_fpu_finish(struct task_struct *new, fpu_switch_t fpu)
{
if (fpu.preload) {
if (unlikely(restore_fpu_checking(new)))
- __thread_fpu_end(new);
+ drop_init_fpu(new);
}
}
@@ -400,17 +438,6 @@ static inline int restore_xstate_sig(void __user *buf, int ia32_frame)
return __restore_xstate_sig(buf, buf_fx, size);
}
-static inline void __drop_fpu(struct task_struct *tsk)
-{
- if (__thread_has_fpu(tsk)) {
- /* Ignore delayed exceptions from user space */
- asm volatile("1: fwait\n"
- "2:\n"
- _ASM_EXTABLE(1b, 2b));
- __thread_fpu_end(tsk);
- }
-}
-
/*
* Need to be preemption-safe.
*
@@ -431,24 +458,18 @@ static inline void user_fpu_begin(void)
static inline void save_init_fpu(struct task_struct *tsk)
{
WARN_ON_ONCE(!__thread_has_fpu(tsk));
+
+ if (use_xsave()) {
+ xsave_state(&tsk->thread.fpu.state->xsave, -1);
+ return;
+ }
+
preempt_disable();
__save_init_fpu(tsk);
__thread_fpu_end(tsk);
preempt_enable();
}
-static inline void drop_fpu(struct task_struct *tsk)
-{
- /*
- * Forget coprocessor state..
- */
- tsk->fpu_counter = 0;
- preempt_disable();
- __drop_fpu(tsk);
- preempt_enable();
- clear_used_math();
-}
-
/*
* i387 state interaction
*/
@@ -503,12 +524,21 @@ static inline void fpu_free(struct fpu *fpu)
}
}
-static inline void fpu_copy(struct fpu *dst, struct fpu *src)
+static inline void fpu_copy(struct task_struct *dst, struct task_struct *src)
{
- memcpy(dst->state, src->state, xstate_size);
-}
+ if (use_xsave()) {
+ struct xsave_struct *xsave = &dst->thread.fpu.state->xsave;
-extern void fpu_finit(struct fpu *fpu);
+ memset(&xsave->xsave_hdr, 0, sizeof(struct xsave_hdr_struct));
+ xsave_state(xsave, -1);
+ } else {
+ struct fpu *dfpu = &dst->thread.fpu;
+ struct fpu *sfpu = &src->thread.fpu;
+
+ unlazy_fpu(src);
+ memcpy(dfpu->state, sfpu->state, xstate_size);
+ }
+}
static inline unsigned long
alloc_mathframe(unsigned long sp, int ia32_frame, unsigned long *buf_fx,
diff --git a/arch/x86/include/asm/i387.h b/arch/x86/include/asm/i387.h
index 257d9cc..6c3bd37 100644
--- a/arch/x86/include/asm/i387.h
+++ b/arch/x86/include/asm/i387.h
@@ -19,6 +19,7 @@ struct pt_regs;
struct user_i387_struct;
extern int init_fpu(struct task_struct *child);
+extern void fpu_finit(struct fpu *fpu);
extern int dump_fpu(struct pt_regs *, struct user_i387_struct *);
extern void math_state_restore(void);
diff --git a/arch/x86/include/asm/xsave.h b/arch/x86/include/asm/xsave.h
index c1d989a..2ddee1b8 100644
--- a/arch/x86/include/asm/xsave.h
+++ b/arch/x86/include/asm/xsave.h
@@ -34,6 +34,7 @@
extern unsigned int xstate_size;
extern u64 pcntxt_mask;
extern u64 xstate_fx_sw_bytes[USER_XSTATE_FX_SW_WORDS];
+extern struct xsave_struct *init_xstate_buf;
extern void xsave_init(void);
extern void update_regset_xstate_info(unsigned int size, u64 xstate_mask);
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index c97bb7b..d0e910d 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -165,10 +165,15 @@ void __init check_bugs(void)
print_cpu_info(&boot_cpu_data);
#endif
check_config();
- check_fpu();
check_hlt();
check_popad();
init_utsname()->machine[1] =
'0' + (boot_cpu_data.x86 > 6 ? 6 : boot_cpu_data.x86);
alternative_instructions();
+
+ /*
+ * kernel_fpu_begin/end() in check_fpu() relies on the patched
+ * alternative instructions.
+ */
+ check_fpu();
}
diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c
index ab6a2e8..5285574 100644
--- a/arch/x86/kernel/i387.c
+++ b/arch/x86/kernel/i387.c
@@ -22,7 +22,15 @@
/*
* Were we in an interrupt that interrupted kernel mode?
*
- * We can do a kernel_fpu_begin/end() pair *ONLY* if that
+ * For now, on xsave platforms we will return interrupted
+ * kernel FPU as not-idle. TBD: As we use non-lazy FPU restore
+ * for xsave platforms, ideally we can change the return value
+ * to something like __thread_has_fpu(current). But we need to
+ * be careful of doing __thread_clear_has_fpu() before saving
+ * the FPU etc for supporting nested uses etc. For now, take
+ * the simple route!
+ *
+ * On others, we can do a kernel_fpu_begin/end() pair *ONLY* if that
* pair does nothing at all: the thread must not have fpu (so
* that we don't try to save the FPU state), and TS must
* be set (so that the clts/stts pair does nothing that is
@@ -30,6 +38,9 @@
*/
static inline bool interrupted_kernel_fpu_idle(void)
{
+ if (use_xsave())
+ return 0;
+
return !__thread_has_fpu(current) &&
(read_cr0() & X86_CR0_TS);
}
@@ -73,7 +84,7 @@ void kernel_fpu_begin(void)
__save_init_fpu(me);
__thread_clear_has_fpu(me);
/* We do 'stts()' in kernel_fpu_end() */
- } else {
+ } else if (!use_xsave()) {
this_cpu_write(fpu_owner_task, NULL);
clts();
}
@@ -82,7 +93,10 @@ EXPORT_SYMBOL(kernel_fpu_begin);
void kernel_fpu_end(void)
{
- stts();
+ if (use_xsave())
+ math_state_restore();
+ else
+ stts();
preempt_enable();
}
EXPORT_SYMBOL(kernel_fpu_end);
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 30069d1..c21e30f 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -66,15 +66,13 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
{
int ret;
- unlazy_fpu(src);
-
*dst = *src;
if (fpu_allocated(&src->thread.fpu)) {
memset(&dst->thread.fpu, 0, sizeof(dst->thread.fpu));
ret = fpu_alloc(&dst->thread.fpu);
if (ret)
return ret;
- fpu_copy(&dst->thread.fpu, &src->thread.fpu);
+ fpu_copy(dst, src);
}
return 0;
}
@@ -153,7 +151,13 @@ void flush_thread(void)
flush_ptrace_hw_breakpoint(tsk);
memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array));
- drop_fpu(tsk);
+ drop_init_fpu(tsk);
+ /*
+ * Free the FPU state for non xsave platforms. They get reallocated
+ * lazily at the first use.
+ */
+ if (!use_xsave())
+ free_thread_xstate(tsk);
}
static void hard_disable_TSC(void)
diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index 516fa18..b9ff83c 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -190,10 +190,6 @@ start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp)
regs->cs = __USER_CS;
regs->ip = new_ip;
regs->sp = new_sp;
- /*
- * Free the old FP and other extended state
- */
- free_thread_xstate(current);
}
EXPORT_SYMBOL_GPL(start_thread);
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 0a980c9..8a6d20c 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -232,10 +232,6 @@ start_thread_common(struct pt_regs *regs, unsigned long new_ip,
regs->cs = _cs;
regs->ss = _ss;
regs->flags = X86_EFLAGS_IF;
- /*
- * Free the old FP and other extended state
- */
- free_thread_xstate(current);
}
void
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index b481341..ac7d527 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -613,11 +613,12 @@ void math_state_restore(void)
}
__thread_fpu_begin(tsk);
+
/*
* Paranoid restore. send a SIGSEGV if we fail to restore the state.
*/
if (unlikely(restore_fpu_checking(tsk))) {
- __thread_fpu_end(tsk);
+ drop_init_fpu(tsk);
force_sig(SIGSEGV, tsk);
return;
}
@@ -629,6 +630,8 @@ EXPORT_SYMBOL_GPL(math_state_restore);
dotraplinkage void __kprobes
do_device_not_available(struct pt_regs *regs, long error_code)
{
+ BUG_ON(use_xsave());
+
#ifdef CONFIG_MATH_EMULATION
if (read_cr0() & X86_CR0_EM) {
struct math_emu_info info = { };
diff --git a/arch/x86/kernel/xsave.c b/arch/x86/kernel/xsave.c
index 4ac5f2e..e7752bd 100644
--- a/arch/x86/kernel/xsave.c
+++ b/arch/x86/kernel/xsave.c
@@ -21,7 +21,7 @@ u64 pcntxt_mask;
/*
* Represents init state for the supported extended state.
*/
-static struct xsave_struct *init_xstate_buf;
+struct xsave_struct *init_xstate_buf;
static struct _fpx_sw_bytes fx_sw_reserved, fx_sw_reserved_ia32;
static unsigned int *xstate_offsets, *xstate_sizes, xstate_features;
@@ -268,7 +268,7 @@ int save_xstate_sig(void __user *buf, void __user *buf_fx, int size)
if (use_fxsr() && save_xstate_epilog(buf_fx, ia32_fxstate))
return -1;
- drop_fpu(tsk); /* trigger finit */
+ drop_init_fpu(tsk); /* trigger finit */
return 0;
}
@@ -340,7 +340,7 @@ int __restore_xstate_sig(void __user *buf, void __user *buf_fx, int size)
config_enabled(CONFIG_IA32_EMULATION));
if (!buf) {
- drop_fpu(tsk);
+ drop_init_fpu(tsk);
return 0;
}
@@ -380,15 +380,30 @@ int __restore_xstate_sig(void __user *buf, void __user *buf_fx, int size)
*/
struct xsave_struct *xsave = &tsk->thread.fpu.state->xsave;
struct user_i387_ia32_struct env;
+ int err = 0;
+ /*
+ * Drop the current fpu which clears used_math(). This ensures
+ * that any context-switch during the copy of the new state,
+ * avoids the intermediate state from getting restored/saved.
+ * Thus avoiding the new restored state from getting corrupted.
+ * We will be ready to restore/save the state only after
+ * set_used_math() is again set.
+ */
drop_fpu(tsk);
if (__copy_from_user(xsave, buf_fx, state_size) ||
- __copy_from_user(&env, buf, sizeof(env)))
- return -1;
+ __copy_from_user(&env, buf, sizeof(env))) {
+ err = -1;
+ } else {
+ sanitize_restored_xstate(tsk, &env, xstate_bv, fx_only);
+ set_used_math();
+ }
- sanitize_restored_xstate(tsk, &env, xstate_bv, fx_only);
- set_used_math();
+ if (use_xsave())
+ math_state_restore();
+
+ return err;
} else {
/*
* For 64-bit frames and 32-bit fsave frames, restore the user
@@ -396,7 +411,7 @@ int __restore_xstate_sig(void __user *buf, void __user *buf_fx, int size)
*/
user_fpu_begin();
if (restore_user_xstate(buf_fx, xstate_bv, fx_only)) {
- drop_fpu(tsk);
+ drop_init_fpu(tsk);
return -1;
}
}
@@ -435,11 +450,29 @@ static void prepare_fx_sw_frame(void)
*/
static inline void xstate_enable(void)
{
+ clts();
set_in_cr4(X86_CR4_OSXSAVE);
xsetbv(XCR_XFEATURE_ENABLED_MASK, pcntxt_mask);
}
/*
+ * This is same as math_state_restore(). But use_xsave() is not yet
+ * patched to use math_state_restore().
+ */
+static inline void init_restore_xstate(void)
+{
+ init_fpu(current);
+ __thread_fpu_begin(current);
+ xrstor_state(init_xstate_buf, -1);
+}
+
+static inline void xstate_enable_ap(void)
+{
+ xstate_enable();
+ init_restore_xstate();
+}
+
+/*
* Record the offsets and sizes of different state managed by the xsave
* memory layout.
*/
@@ -479,7 +512,6 @@ static void __init setup_xstate_init(void)
__alignof__(struct xsave_struct));
init_xstate_buf->i387.mxcsr = MXCSR_DEFAULT;
- clts();
/*
* Init all the features state with header_bv being 0x0
*/
@@ -489,7 +521,6 @@ static void __init setup_xstate_init(void)
* of any feature which is not represented by all zero's.
*/
xsave_state(init_xstate_buf, -1);
- stts();
}
/*
@@ -533,6 +564,10 @@ static void __init xstate_enable_boot_cpu(void)
pr_info("enabled xstate_bv 0x%llx, cntxt size 0x%x\n",
pcntxt_mask, xstate_size);
+
+ current->thread.fpu.state =
+ alloc_bootmem_align(xstate_size, __alignof__(struct xsave_struct));
+ init_restore_xstate();
}
/*
@@ -551,6 +586,6 @@ void __cpuinit xsave_init(void)
return;
this_func = next_func;
- next_func = xstate_enable;
+ next_func = xstate_enable_ap;
this_func();
}
generated by cgit v0.10.2 at 2024-07-16 16:49:58 (GMT)