[patch 8/9] x86, xsave: save/restore the extended state context in sigframe
From: Suresh Siddha
Date: Tue Jul 29 2008 - 13:42:33 EST
On cpu's supporting xsave/xrstor, fpstate pointer in the sigcontext, will
include the extended state information along with fpstate information. Presence
of extended state information is indicated by the presence
of FP_XSTATE_MAGIC1 at fpstate.sw_reserved.magic1 and FP_XSTATE_MAGIC2
at fpstate + (fpstate.sw_reserved.extended_size - FP_XSTATE_MAGIC2_SIZE).
Extended feature bit mask that is saved in the memory layout is represented
by the fpstate.sw_reserved.xstate_bv
For RT signal frames, UC_FP_XSTATE in the uc_flags also indicate the
presence of extended state information in the sigcontext's fpstate
pointer.
Signed-off-by: Suresh Siddha <suresh.b.siddha@xxxxxxxxx>
---
Index: tip-0728/arch/x86/kernel/xsave.c
===================================================================
--- tip-0728.orig/arch/x86/kernel/xsave.c 2008-07-28 18:50:02.000000000 -0700
+++ tip-0728/arch/x86/kernel/xsave.c 2008-07-28 18:51:24.000000000 -0700
@@ -6,12 +6,68 @@
#include <linux/bootmem.h>
#include <linux/compat.h>
#include <asm/i387.h>
+#ifdef CONFIG_IA32_EMULATION
+#include <asm/sigcontext32.h>
+#endif
/*
* Supported feature mask by the CPU and the kernel.
*/
unsigned int pcntxt_hmask, pcntxt_lmask;
+struct _fpx_sw_bytes fx_sw_reserved;
+#ifdef CONFIG_IA32_EMULATION
+struct _fpx_sw_bytes fx_sw_reserved_ia32;
+#endif
+
+/*
+ * Check for the presence of extended state information in the
+ * user fpstate pointer in the sigcontext.
+ */
+int check_for_xstate(struct i387_fxsave_struct __user *buf,
+ void __user *fpstate,
+ struct _fpx_sw_bytes *fx_sw_user)
+{
+ int min_xstate_size = sizeof(struct i387_fxsave_struct) +
+ sizeof(struct xsave_hdr_struct);
+ unsigned int magic2;
+ int err;
+
+ err = __copy_from_user(fx_sw_user, &buf->sw_reserved[0],
+ sizeof(struct _fpx_sw_bytes));
+
+ if (err)
+ return err;
+
+ /*
+ * First Magic check failed.
+ */
+ if (fx_sw_user->magic1 != FP_XSTATE_MAGIC1)
+ return -1;
+
+ /*
+ * Check for error scenarios.
+ */
+ if (fx_sw_user->xstate_size < min_xstate_size ||
+ fx_sw_user->xstate_size > xstate_size ||
+ fx_sw_user->xstate_size > fx_sw_user->extended_size)
+ return -1;
+
+ err = __get_user(magic2, (__u32 *) (((void *)fpstate) +
+ fx_sw_user->extended_size -
+ FP_XSTATE_MAGIC2_SIZE));
+ /*
+ * Check for the presence of second magic word at the end of memory
+ * layout. This detects the case where the user just copied the legacy
+ * fpstate layout with out copying the extended state information
+ * in the memory layout.
+ */
+ if (err || magic2 != FP_XSTATE_MAGIC2)
+ return -1;
+
+ return 0;
+}
+
#ifdef CONFIG_X86_64
/*
* Signal frame handlers.
@@ -28,15 +84,18 @@
BUILD_BUG_ON(sizeof(struct user_i387_struct) !=
sizeof(tsk->thread.xstate->fxsave));
- if ((unsigned long)buf % 16)
+ if ((unsigned long)buf % 64)
printk("save_i387_xstate: bad fpstate %p\n", buf);
if (!used_math())
return 0;
clear_used_math(); /* trigger finit */
if (task_thread_info(tsk)->status & TS_USEDFPU) {
- err = save_i387_checking((struct i387_fxsave_struct __user *)
- buf);
+ if (task_thread_info(tsk)->status & TS_XSAVE)
+ err = xsave_user(buf);
+ else
+ err = fxsave_user(buf);
+
if (err)
return err;
task_thread_info(tsk)->status &= ~TS_USEDFPU;
@@ -46,23 +105,77 @@
xstate_size))
return -1;
}
+
+ if (task_thread_info(tsk)->status & TS_XSAVE) {
+ struct _fpstate __user *fx = buf;
+
+ err = __copy_to_user(&fx->sw_reserved, &fx_sw_reserved,
+ sizeof(struct _fpx_sw_bytes));
+
+ err |= __put_user(FP_XSTATE_MAGIC2,
+ (__u32 __user *) (buf + sig_xstate_size
+ - FP_XSTATE_MAGIC2_SIZE));
+ }
+
return 1;
}
/*
+ * Restore the extended state if present. Otherwise, restore the FP/SSE
+ * state.
+ */
+int restore_user_xstate(void __user *buf)
+{
+ struct _fpx_sw_bytes fx_sw_user;
+ unsigned int lmask, hmask;
+ int err;
+
+ if (((unsigned long)buf % 64) ||
+ check_for_xstate(buf, buf, &fx_sw_user))
+ goto fx_only;
+
+ lmask = fx_sw_user.xstate_bv;
+ hmask = fx_sw_user.xstate_bv >> 32;
+
+ /*
+ * restore the state passed by the user.
+ */
+ err = xrestore_user(buf, lmask, hmask);
+ if (err)
+ return err;
+
+ /*
+ * init the state skipped by the user.
+ */
+ lmask = pcntxt_lmask & ~lmask;
+ hmask = pcntxt_hmask & ~hmask;
+
+ xrstor_state(init_xstate_buf, lmask, hmask);
+
+ return 0;
+
+fx_only:
+ /*
+ * couldn't find the extended state information in the
+ * memory layout. Restore just the FP/SSE and init all
+ * the other extended state.
+ */
+ xrstor_state(init_xstate_buf, pcntxt_lmask & ~XSTATE_FPSSE,
+ pcntxt_hmask);
+ return fxrstor_checking((__force struct i387_fxsave_struct *)buf);
+}
+
+/*
* This restores directly out of user space. Exceptions are handled.
*/
int restore_i387_xstate(void __user *buf)
{
struct task_struct *tsk = current;
- int err;
+ int err = 0;
if (!buf) {
- if (used_math()) {
- clear_fpu(tsk);
- clear_used_math();
- }
-
+ if (used_math())
+ goto clear;
return 0;
} else
if (!access_ok(VERIFY_READ, buf, sig_xstate_size))
@@ -78,12 +191,17 @@
clts();
task_thread_info(current)->status |= TS_USEDFPU;
}
- err = fxrstor_checking((__force struct i387_fxsave_struct *)buf);
+ if (task_thread_info(tsk)->status & TS_XSAVE)
+ err = restore_user_xstate(buf);
+ else
+ err = fxrstor_checking((__force struct i387_fxsave_struct *)
+ buf);
if (unlikely(err)) {
/*
* Encountered an error while doing the restore from the
* user buffer, clear the fpu state.
*/
+clear:
clear_fpu(tsk);
clear_used_math();
}
@@ -92,6 +210,38 @@
#endif
/*
+ * Prepare the SW reserved portion of the fxsave memory layout, indicating
+ * the presence of the extended state information in the memory layout
+ * pointed by the fpstate pointer in the sigcontext.
+ * This will be saved when ever the FP and extended state context is
+ * saved on the user stack during the signal handler delivery to the user.
+ */
+void prepare_fx_sw_frame(void)
+{
+ int size_extended = (xstate_size - sizeof(struct i387_fxsave_struct)) +
+ FP_XSTATE_MAGIC2_SIZE;
+
+ sig_xstate_size = sizeof(struct _fpstate) + size_extended;
+
+#ifdef CONFIG_IA32_EMULATION
+ sig_xstate_ia32_size = sizeof(struct _fpstate_ia32) + size_extended;
+#endif
+
+ memset(&fx_sw_reserved, 0, sizeof(fx_sw_reserved));
+
+ fx_sw_reserved.magic1 = FP_XSTATE_MAGIC1;
+ fx_sw_reserved.extended_size = sig_xstate_size;
+ fx_sw_reserved.xstate_bv = pcntxt_lmask |
+ (((u64) (pcntxt_hmask)) << 32);
+ fx_sw_reserved.xstate_size = xstate_size;
+#ifdef CONFIG_IA32_EMULATION
+ memcpy(&fx_sw_reserved_ia32, &fx_sw_reserved,
+ sizeof(struct _fpx_sw_bytes));
+ fx_sw_reserved_ia32.extended_size = sig_xstate_ia32_size;
+#endif
+}
+
+/*
* Represents init state for the supported extended state.
*/
struct xsave_struct *init_xstate_buf;
@@ -162,6 +312,8 @@
xstate_size = ebx;
+ prepare_fx_sw_frame();
+
setup_xstate_init();
printk(KERN_INFO "xsave/xrstor: enabled xstate_bv %Lx, cntxt size %x\n",
Index: tip-0728/arch/x86/kernel/i387.c
===================================================================
--- tip-0728.orig/arch/x86/kernel/i387.c 2008-07-28 18:50:02.000000000 -0700
+++ tip-0728/arch/x86/kernel/i387.c 2008-07-28 18:50:08.000000000 -0700
@@ -26,6 +26,7 @@
# define _fpstate_ia32 _fpstate
# define _xstate_ia32 _xstate
# define sig_xstate_ia32_size sig_xstate_size
+# define fx_sw_reserved_ia32 fx_sw_reserved
# define user_i387_ia32_struct user_i387_struct
# define user32_fxsr_struct user_fxsr_struct
#endif
@@ -447,12 +448,30 @@
if (err)
return -1;
- if (__copy_to_user(&buf->_fxsr_env[0], fx,
- sizeof(struct i387_fxsave_struct)))
+ if (__copy_to_user(&buf->_fxsr_env[0], fx, xstate_size))
return -1;
return 1;
}
+static int save_i387_xsave(void __user *buf)
+{
+ struct _fpstate_ia32 __user *fx = buf;
+ int err = 0;
+
+ if (save_i387_fxsave(fx) < 0)
+ return -1;
+
+ err = __copy_to_user(&fx->sw_reserved, &fx_sw_reserved_ia32,
+ sizeof(struct _fpx_sw_bytes));
+ err |= __put_user(FP_XSTATE_MAGIC2,
+ (__u32 __user *) (buf + sig_xstate_ia32_size
+ - FP_XSTATE_MAGIC2_SIZE));
+ if (err)
+ return -1;
+
+ return 1;
+}
+
int save_i387_xstate_ia32(void __user *buf)
{
struct _fpstate_ia32 __user *fp = (struct _fpstate_ia32 __user *) buf;
@@ -477,6 +496,8 @@
unlazy_fpu(tsk);
+ if (cpu_has_xsave)
+ return save_i387_xsave(fp);
if (cpu_has_fxsr)
return save_i387_fxsave(fp);
else
@@ -491,14 +512,15 @@
sizeof(struct i387_fsave_struct));
}
-static int restore_i387_fxsave(struct _fpstate_ia32 __user *buf)
+static int restore_i387_fxsave(struct _fpstate_ia32 __user *buf,
+ unsigned int size)
{
struct task_struct *tsk = current;
struct user_i387_ia32_struct env;
int err;
err = __copy_from_user(&tsk->thread.xstate->fxsave, &buf->_fxsr_env[0],
- sizeof(struct i387_fxsave_struct));
+ size);
/* mxcsr reserved bits must be masked to zero for security reasons */
tsk->thread.xstate->fxsave.mxcsr &= mxcsr_feature_mask;
if (err || __copy_from_user(&env, buf, sizeof(env)))
@@ -508,6 +530,51 @@
return 0;
}
+static int restore_i387_xsave(void __user *buf)
+{
+ struct _fpx_sw_bytes fx_sw_user;
+ struct _fpstate_ia32 __user *fx_user =
+ ((struct _fpstate_ia32 __user *) buf);
+ struct i387_fxsave_struct __user *fx =
+ (struct i387_fxsave_struct __user *) &fx_user->_fxsr_env[0];
+ struct xsave_hdr_struct *xsave_hdr =
+ ¤t->thread.xstate->xsave.xsave_hdr;
+ unsigned int lmask, hmask;
+ int err;
+
+ if (check_for_xstate(fx, buf, &fx_sw_user))
+ goto fx_only;
+
+ lmask = fx_sw_user.xstate_bv;
+ hmask = fx_sw_user.xstate_bv >> 32;
+
+ err = restore_i387_fxsave(buf, fx_sw_user.xstate_size);
+
+ xsave_hdr->xstate_bv &= (pcntxt_lmask | (((u64) pcntxt_hmask) << 32));
+ /*
+ * These bits must be zero.
+ */
+ xsave_hdr->reserved1[0] = xsave_hdr->reserved1[1] = 0;
+
+ /*
+ * Init the state that is not present in the memory layout
+ * and enabled by the OS.
+ */
+ lmask = ~(pcntxt_lmask & ~lmask);
+ hmask = ~(pcntxt_hmask & ~hmask);
+ xsave_hdr->xstate_bv &= (lmask | (((u64) hmask) << 32));
+
+ return err;
+fx_only:
+ /*
+ * Couldn't find the extended state information in the memory
+ * layout. Restore the FP/SSE and init the other extended state
+ * enabled by the OS.
+ */
+ xsave_hdr->xstate_bv = XSTATE_FPSSE;
+ return restore_i387_fxsave(buf, sizeof(struct i387_fxsave_struct));
+}
+
int restore_i387_xstate_ia32(void __user *buf)
{
int err;
@@ -535,8 +602,11 @@
}
if (HAVE_HWFP) {
- if (cpu_has_fxsr)
- err = restore_i387_fxsave(fp);
+ if (cpu_has_xsave)
+ err = restore_i387_xsave(buf);
+ else if (cpu_has_fxsr)
+ err = restore_i387_fxsave(fp, sizeof(struct
+ i387_fxsave_struct));
else
err = restore_i387_fsave(fp);
} else {
Index: tip-0728/arch/x86/kernel/signal_64.c
===================================================================
--- tip-0728.orig/arch/x86/kernel/signal_64.c 2008-07-28 18:50:02.000000000 -0700
+++ tip-0728/arch/x86/kernel/signal_64.c 2008-07-28 18:50:08.000000000 -0700
@@ -195,7 +195,7 @@
sp = current->sas_ss_sp + current->sas_ss_size;
}
- return (void __user *)round_down(sp - size, 16);
+ return (void __user *)round_down(sp - size, 64);
}
static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
@@ -229,7 +229,10 @@
}
/* Create the ucontext. */
- err |= __put_user(0, &frame->uc.uc_flags);
+ if (cpu_has_xsave)
+ err |= __put_user(UC_FP_XSTATE, &frame->uc.uc_flags);
+ else
+ err |= __put_user(0, &frame->uc.uc_flags);
err |= __put_user(0, &frame->uc.uc_link);
err |= __put_user(me->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
err |= __put_user(sas_ss_flags(regs->sp),
Index: tip-0728/include/asm-x86/i387.h
===================================================================
--- tip-0728.orig/include/asm-x86/i387.h 2008-07-28 18:50:02.000000000 -0700
+++ tip-0728/include/asm-x86/i387.h 2008-07-28 18:50:08.000000000 -0700
@@ -32,8 +32,10 @@
extern user_regset_get_fn fpregs_get, xfpregs_get, fpregs_soft_get;
extern user_regset_set_fn fpregs_set, xfpregs_set, fpregs_soft_set;
+extern struct _fpx_sw_bytes fx_sw_reserved;
#ifdef CONFIG_IA32_EMULATION
extern unsigned int sig_xstate_ia32_size;
+extern struct _fpx_sw_bytes fx_sw_reserved_ia32;
struct _fpstate_ia32;
struct _xstate_ia32;
extern int save_i387_xstate_ia32(void __user *buf);
@@ -105,7 +107,7 @@
X86_FEATURE_FXSAVE_LEAK);
}
-static inline int save_i387_checking(struct i387_fxsave_struct __user *fx)
+static inline int fxsave_user(struct i387_fxsave_struct __user *fx)
{
int err;
Index: tip-0728/include/asm-x86/xsave.h
===================================================================
--- tip-0728.orig/include/asm-x86/xsave.h 2008-07-28 18:50:02.000000000 -0700
+++ tip-0728/include/asm-x86/xsave.h 2008-07-28 18:50:08.000000000 -0700
@@ -29,6 +29,9 @@
extern void xsave_cntxt_init(void);
extern void xsave_init(void);
extern int init_fpu(struct task_struct *child);
+extern int check_for_xstate(struct i387_fxsave_struct __user *buf,
+ void __user *fpstate,
+ struct _fpx_sw_bytes *sw);
static inline int xrstor_checking(struct xsave_struct *fx)
{
@@ -48,7 +51,7 @@
return err;
}
-static inline int xsave_check(struct xsave_struct __user *buf)
+static inline int xsave_user(struct xsave_struct __user *buf)
{
int err;
__asm__ __volatile__("1: .byte " REX_PREFIX "0x0f,0xae,0x27\n"
Index: tip-0728/include/asm-x86/ucontext.h
===================================================================
--- tip-0728.orig/include/asm-x86/ucontext.h 2008-07-28 18:49:10.000000000 -0700
+++ tip-0728/include/asm-x86/ucontext.h 2008-07-28 18:50:08.000000000 -0700
@@ -1,6 +1,12 @@
#ifndef ASM_X86__UCONTEXT_H
#define ASM_X86__UCONTEXT_H
+#define UC_FP_XSTATE 0x1 /* indicates the presence of extended state
+ * information in the memory layout pointed
+ * by the fpstate pointer in the ucontext's
+ * sigcontext struct (uc_mcontext).
+ */
+
struct ucontext {
unsigned long uc_flags;
struct ucontext *uc_link;
Index: tip-0728/arch/x86/ia32/ia32_signal.c
===================================================================
--- tip-0728.orig/arch/x86/ia32/ia32_signal.c 2008-07-28 18:50:02.000000000 -0700
+++ tip-0728/arch/x86/ia32/ia32_signal.c 2008-07-28 18:50:08.000000000 -0700
@@ -544,7 +544,10 @@
goto give_sigsegv;
/* Create the ucontext. */
- err |= __put_user(0, &frame->uc.uc_flags);
+ if (cpu_has_xsave)
+ err |= __put_user(UC_FP_XSTATE, &frame->uc.uc_flags);
+ else
+ err |= __put_user(0, &frame->uc.uc_flags);
err |= __put_user(0, &frame->uc.uc_link);
err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
err |= __put_user(sas_ss_flags(regs->sp),
Index: tip-0728/arch/x86/kernel/signal_32.c
===================================================================
--- tip-0728.orig/arch/x86/kernel/signal_32.c 2008-07-28 18:50:02.000000000 -0700
+++ tip-0728/arch/x86/kernel/signal_32.c 2008-07-28 18:50:08.000000000 -0700
@@ -443,7 +443,10 @@
goto give_sigsegv;
/* Create the ucontext. */
- err |= __put_user(0, &frame->uc.uc_flags);
+ if (cpu_has_xsave)
+ err |= __put_user(UC_FP_XSTATE, &frame->uc.uc_flags);
+ else
+ err |= __put_user(0, &frame->uc.uc_flags);
err |= __put_user(0, &frame->uc.uc_link);
err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
err |= __put_user(sas_ss_flags(regs->sp),
--
--
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