system/linux
system/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux synced 2024-10-11 13:55:09 +00:00
Code Issues Packages Projects Releases Wiki Activity

x86/fpu/xstate: Define and use 'fpu_user_xstate_size'

Browse source 
The kernel xstate area can be in standard or compacted format;
it is always in standard format for user mode. When XSAVES is
enabled, the kernel uses the compacted format and it is necessary
to use a separate fpu_user_xstate_size for signal/ptrace frames.

Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
[ Rebased the patch and cleaned up the naming. ]
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
Reviewed-by: Dave Hansen <dave.hansen@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Ravi V. Shankar <ravi.v.shankar@intel.com>
Cc: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/8756ec34dabddfc727cda5743195eb81e8caf91c.1463760376.git.yu-cheng.yu@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Fenghua Yu 2016-05-20 10:47:05 -07:00 committed by Ingo Molnar
parent d1898b7336
commit a1141e0b5c
5 changed files with 73 additions and 37 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

1
arch/x86/include/asm/fpu/xstate.h
View file

@ -39,7 +39,6 @@
#define REX_PREFIX
#endif
extern unsigned int xstate_size;
extern u64 xfeatures_mask;
extern u64 xstate_fx_sw_bytes[USER_XSTATE_FX_SW_WORDS];

1
arch/x86/include/asm/processor.h
View file

@ -368,6 +368,7 @@ DECLARE_PER_CPU(struct irq_stack *, softirq_stack);
#endif /* X86_64 */
extern unsigned int xstate_size;
extern unsigned int fpu_user_xstate_size;
struct perf_event;

5
arch/x86/kernel/fpu/init.c
View file

@ -195,7 +195,7 @@ static void __init fpu__init_task_struct_size(void)
}
/*
* Set up the xstate_size based on the legacy FPU context size.
* Set up the user and kernel xstate_size based on the legacy FPU context size.
*
* We set this up first, and later it will be overwritten by
* fpu__init_system_xstate() if the CPU knows about xstates.
@ -226,6 +226,9 @@ static void __init fpu__init_system_xstate_size_legacy(void)
else
xstate_size = sizeof(struct fregs_state);
}
fpu_user_xstate_size = xstate_size;
/*
* Quirk: we don't yet handle the XSAVES* instructions
* correctly, as we don't correctly convert between

27
arch/x86/kernel/fpu/signal.c
View file

@ -32,7 +32,7 @@ static inline int check_for_xstate(struct fxregs_state __user *buf,
/* Check for the first magic field and other error scenarios. */
if (fx_sw->magic1 != FP_XSTATE_MAGIC1 ||
fx_sw->xstate_size < min_xstate_size ||
fx_sw->xstate_size > xstate_size ||
fx_sw->xstate_size > fpu_user_xstate_size ||
fx_sw->xstate_size > fx_sw->extended_size)
return -1;
@ -89,7 +89,8 @@ static inline int save_xstate_epilog(void __user *buf, int ia32_frame)
if (!use_xsave())
return err;
err |= __put_user(FP_XSTATE_MAGIC2, (__u32 *)(buf + xstate_size));
err |= __put_user(FP_XSTATE_MAGIC2,
(__u32 *)(buf + fpu_user_xstate_size));
/*
* Read the xfeatures which we copied (directly from the cpu or
@ -126,7 +127,7 @@ static inline int copy_fpregs_to_sigframe(struct xregs_state __user *buf)
else
err = copy_fregs_to_user((struct fregs_state __user *) buf);
if (unlikely(err) && __clear_user(buf, xstate_size))
if (unlikely(err) && __clear_user(buf, fpu_user_xstate_size))
err = -EFAULT;
return err;
}
@ -176,8 +177,19 @@ int copy_fpstate_to_sigframe(void __user *buf, void __user *buf_fx, int size)
if (ia32_fxstate)
copy_fxregs_to_kernel(&tsk->thread.fpu);
} else {
/*
* It is a *bug* if kernel uses compacted-format for xsave
* area and we copy it out directly to a signal frame. It
* should have been handled above by saving the registers
* directly.
*/
if (boot_cpu_has(X86_FEATURE_XSAVES)) {
WARN_ONCE(1, "x86/fpu: saving compacted-format xsave area to a signal frame!\n");
return -1;
}
fpstate_sanitize_xstate(&tsk->thread.fpu);
if (__copy_to_user(buf_fx, xsave, xstate_size))
if (__copy_to_user(buf_fx, xsave, fpu_user_xstate_size))
return -1;
}
@ -344,7 +356,8 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
static inline int xstate_sigframe_size(void)
{
return use_xsave() ? xstate_size + FP_XSTATE_MAGIC2_SIZE : xstate_size;
return use_xsave() ? fpu_user_xstate_size + FP_XSTATE_MAGIC2_SIZE :
fpu_user_xstate_size;
}
/*
@ -388,12 +401,12 @@ fpu__alloc_mathframe(unsigned long sp, int ia32_frame,
*/
void fpu__init_prepare_fx_sw_frame(void)
{
int size = xstate_size + FP_XSTATE_MAGIC2_SIZE;
int size = fpu_user_xstate_size + FP_XSTATE_MAGIC2_SIZE;
fx_sw_reserved.magic1 = FP_XSTATE_MAGIC1;
fx_sw_reserved.extended_size = size;
fx_sw_reserved.xfeatures = xfeatures_mask;
fx_sw_reserved.xstate_size = xstate_size;
fx_sw_reserved.xstate_size = fpu_user_xstate_size;
if (config_enabled(CONFIG_IA32_EMULATION) ||
config_enabled(CONFIG_X86_32)) {

76
arch/x86/kernel/fpu/xstate.c
View file

@ -43,6 +43,13 @@ static unsigned int xstate_offsets[XFEATURE_MAX] = { [ 0 ... XFEATURE_MAX - 1] =
static unsigned int xstate_sizes[XFEATURE_MAX] = { [ 0 ... XFEATURE_MAX - 1] = -1};
static unsigned int xstate_comp_offsets[sizeof(xfeatures_mask)*8];
/*
* The XSAVE area of kernel can be in standard or compacted format;
* it is always in standard format for user mode. This is the user
* mode standard format size used for signal and ptrace frames.
*/
unsigned int fpu_user_xstate_size;
/*
* Clear all of the X86_FEATURE_* bits that are unavailable
* when the CPU has no XSAVE support.
@ -171,7 +178,7 @@ void fpstate_sanitize_xstate(struct fpu *fpu)
*/
while (xfeatures) {
if (xfeatures & 0x1) {
int offset = xstate_offsets[feature_bit];
int offset = xstate_comp_offsets[feature_bit];
int size = xstate_sizes[feature_bit];
memcpy((void *)fx + offset,
@ -533,8 +540,9 @@ static void do_extra_xstate_size_checks(void)
XSTATE_WARN_ON(paranoid_xstate_size != xstate_size);
}
/*
* Calculate total size of enabled xstates in XCR0/xfeatures_mask.
* Get total size of enabled xstates in XCR0/xfeatures_mask.
*
* 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
@ -544,34 +552,33 @@ static void do_extra_xstate_size_checks(void)
* Note that we do not currently set any bits on IA32_XSS so
* 'XCR0 | IA32_XSS == XCR0' for now.
*/
static unsigned int __init calculate_xstate_size(void)
static unsigned int __init get_xsaves_size(void)
{
unsigned int eax, ebx, ecx, edx;
unsigned int calculated_xstate_size;
/*
* - CPUID function 0DH, sub-function 1:
* EBX enumerates the size (in bytes) required by
* the XSAVES instruction for an XSAVE area
* containing all the state components
* corresponding to bits currently set in
* XCR0 | IA32_XSS.
*/
cpuid_count(XSTATE_CPUID, 1, &eax, &ebx, &ecx, &edx);
return ebx;
}
if (!boot_cpu_has(X86_FEATURE_XSAVES)) {
/*
* - CPUID function 0DH, sub-function 0:
* EBX enumerates the size (in bytes) required by
* the XSAVE instruction for an XSAVE area
* containing all the *user* state components
* corresponding to bits currently set in XCR0.
*/
cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx);
calculated_xstate_size = ebx;
} else {
/*
* - CPUID function 0DH, sub-function 1:
* EBX enumerates the size (in bytes) required by
* the XSAVES instruction for an XSAVE area
* containing all the state components
* corresponding to bits currently set in
* XCR0 | IA32_XSS.
*/
cpuid_count(XSTATE_CPUID, 1, &eax, &ebx, &ecx, &edx);
calculated_xstate_size = ebx;
}
return calculated_xstate_size;
static unsigned int __init get_xsave_size(void)
{
unsigned int eax, ebx, ecx, edx;
/*
* - CPUID function 0DH, sub-function 0:
* EBX enumerates the size (in bytes) required by
* the XSAVE instruction for an XSAVE area
* containing all the *user* state components
* corresponding to bits currently set in XCR0.
*/
cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx);
return ebx;
}
/*
@ -591,7 +598,15 @@ static bool is_supported_xstate_size(unsigned int test_xstate_size)
static int init_xstate_size(void)
{
/* Recompute the context size for enabled features: */
unsigned int possible_xstate_size = calculate_xstate_size();
unsigned int possible_xstate_size;
unsigned int xsave_size;
xsave_size = get_xsave_size();
if (boot_cpu_has(X86_FEATURE_XSAVES))
possible_xstate_size = get_xsaves_size();
else
possible_xstate_size = xsave_size;
/* Ensure we have the space to store all enabled: */
if (!is_supported_xstate_size(possible_xstate_size))
@ -603,6 +618,11 @@ static int init_xstate_size(void)
*/
xstate_size = possible_xstate_size;
do_extra_xstate_size_checks();
/*
* User space is always in standard format.
*/
fpu_user_xstate_size = xsave_size;
return 0;
}