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x86, ptrace: regset extensions to support xstate 

Add the xstate regset support which helps extend the kernel ptrace and the
core-dump interfaces to support AVX state etc.

This regset interface is designed to support all the future state that gets
supported using xsave/xrstor infrastructure.

Looking at the memory layout saved by "xsave", one can't say which state
is represented in the memory layout. This is because if a particular state is
in init state, in the xsave hdr it can be represented by bit '0'. And hence
we can't really say by the xsave header wether a state is in init state or
the state is not saved in the memory layout.

And hence the xsave memory layout available through this regset
interface uses SW usable bytes [464..511] to convey what state is represented
in the memory layout.

First 8 bytes of the sw_usable_bytes[464..467] will be set to OS enabled xstate
mask(which is same as the 64bit mask returned by the xgetbv's xCR0).

The note NT_X86_XSTATE represents the extended state information in the
core file, using the above mentioned memory layout.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
LKML-Reference: <20100211195614.802495327@sbs-t61.sc.intel.com>
Signed-off-by: Hongjiu Lu <hjl.tools@gmail.com>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
This commit is contained in:
Suresh Siddha 2010-02-11 11:50:59 -08:00 committed by H. Peter Anvin
parent 676ad58553
commit 5b3efd5008
7 changed files with 187 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
arch/x86/include/asm/i387.h
View File

@ -33,8 +33,16 @@ extern void init_thread_xstate(void);
extern int dump_fpu(struct pt_regs *, struct user_i387_struct *);
extern user_regset_active_fn fpregs_active, xfpregs_active;
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 user_regset_get_fn fpregs_get, xfpregs_get, fpregs_soft_get,
xstateregs_get;
extern user_regset_set_fn fpregs_set, xfpregs_set, fpregs_soft_set,
xstateregs_set;
/*
* xstateregs_active == fpregs_active. Please refer to the comment
* at the definition of fpregs_active.
*/
#define xstateregs_active fpregs_active
extern struct _fpx_sw_bytes fx_sw_reserved;
#ifdef CONFIG_IA32_EMULATION

58
arch/x86/include/asm/user.h
View File

@ -1,5 +1,63 @@
#ifndef _ASM_X86_USER_H
#define _ASM_X86_USER_H
#ifdef CONFIG_X86_32
# include "user_32.h"
#else
# include "user_64.h"
#endif
#include <asm/types.h>
struct user_ymmh_regs {
/* 16 * 16 bytes for each YMMH-reg */
__u32 ymmh_space[64];
};
struct user_xsave_hdr {
__u64 xstate_bv;
__u64 reserved1[2];
__u64 reserved2[5];
};
/*
* The structure layout of user_xstateregs, used for exporting the
* extended register state through ptrace and core-dump (NT_X86_XSTATE note)
* interfaces will be same as the memory layout of xsave used by the processor
* (except for the bytes 464..511, which can be used by the software) and hence
* the size of this structure varies depending on the features supported by the
* processor and OS. The size of the structure that users need to use can be
* obtained by doing:
* cpuid_count(0xd, 0, &eax, &ptrace_xstateregs_struct_size, &ecx, &edx);
* i.e., cpuid.(eax=0xd,ecx=0).ebx will be the size that user (debuggers, etc.)
* need to use.
*
* For now, only the first 8 bytes of the software usable bytes[464..471] will
* be used and will be set to OS enabled xstate mask (which is same as the
* 64bit mask returned by the xgetbv's xCR0). Users (analyzing core dump
* remotely, etc.) can use this mask as well as the mask saved in the
* xstate_hdr bytes and interpret what states the processor/OS supports
* and what states are in modified/initialized conditions for the
* particular process/thread.
*
* Also when the user modifies certain state FP/SSE/etc through the
* ptrace interface, they must ensure that the xsave_hdr.xstate_bv
* bytes[512..519] of the memory layout are updated correspondingly.
* i.e., for example when FP state is modified to a non-init state,
* xsave_hdr.xstate_bv's bit 0 must be set to '1', when SSE is modified to
* non-init state, xsave_hdr.xstate_bv's bit 1 must to be set to '1', etc.
*/
#define USER_XSTATE_FX_SW_WORDS 6
#define USER_XSTATE_XCR0_WORD 0
struct user_xstateregs {
struct {
__u64 fpx_space[58];
__u64 xstate_fx_sw[USER_XSTATE_FX_SW_WORDS];
} i387;
struct user_xsave_hdr xsave_hdr;
struct user_ymmh_regs ymmh;
/* further processor state extensions go here */
};
#endif /* _ASM_X86_USER_H */

2
arch/x86/include/asm/xsave.h
View File

@ -27,9 +27,11 @@
extern unsigned int xstate_size;
extern u64 pcntxt_mask;
extern struct xsave_struct *init_xstate_buf;
extern u64 xstate_fx_sw_bytes[USER_XSTATE_FX_SW_WORDS];
extern void xsave_cntxt_init(void);
extern void xsave_init(void);
extern void update_regset_xstate_info(unsigned int size, u64 xstate_mask);
extern int init_fpu(struct task_struct *child);
extern int check_for_xstate(struct i387_fxsave_struct __user *buf,
void __user *fpstate,

83
arch/x86/kernel/i387.c
View File

@ -164,6 +164,11 @@ int init_fpu(struct task_struct *tsk)
return 0;
}
/*
* The xstateregs_active() routine is the same as the fpregs_active() routine,
* as the "regset->n" for the xstate regset will be updated based on the feature
* capabilites supported by the xsave.
*/
int fpregs_active(struct task_struct *target, const struct user_regset *regset)
{
return tsk_used_math(target) ? regset->n : 0;
@ -224,6 +229,84 @@ int xfpregs_set(struct task_struct *target, const struct user_regset *regset,
return ret;
}
int xstateregs_get(struct task_struct *target, const struct user_regset *regset,
unsigned int pos, unsigned int count,
void *kbuf, void __user *ubuf)
{
int ret;
if (!cpu_has_xsave)
return -ENODEV;
ret = init_fpu(target);
if (ret)
return ret;
/*
* First copy the fxsave bytes 0..463.
*/
ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
&target->thread.xstate->xsave, 0,
offsetof(struct user_xstateregs,
i387.xstate_fx_sw));
if (ret)
return ret;
/*
* Copy the 48bytes defined by software.
*/
ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
xstate_fx_sw_bytes,
offsetof(struct user_xstateregs,
i387.xstate_fx_sw),
offsetof(struct user_xstateregs,
xsave_hdr));
if (ret)
return ret;
/*
* Copy the rest of xstate memory layout.
*/
ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
&target->thread.xstate->xsave.xsave_hdr,
offsetof(struct user_xstateregs,
xsave_hdr), -1);
return ret;
}
int xstateregs_set(struct task_struct *target, const struct user_regset *regset,
unsigned int pos, unsigned int count,
const void *kbuf, const void __user *ubuf)
{
int ret;
struct xsave_hdr_struct *xsave_hdr;
if (!cpu_has_xsave)
return -ENODEV;
ret = init_fpu(target);
if (ret)
return ret;
ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
&target->thread.xstate->xsave, 0, -1);
/*
* mxcsr reserved bits must be masked to zero for security reasons.
*/
target->thread.xstate->fxsave.mxcsr &= mxcsr_feature_mask;
xsave_hdr = &target->thread.xstate->xsave.xsave_hdr;
xsave_hdr->xstate_bv &= pcntxt_mask;
/*
* These bits must be zero.
*/
xsave_hdr->reserved1[0] = xsave_hdr->reserved1[1] = 0;
return ret;
}
#if defined CONFIG_X86_32 || defined CONFIG_IA32_EMULATION
/*

34
arch/x86/kernel/ptrace.c
View File

@ -48,6 +48,7 @@ enum x86_regset {
REGSET_FP,
REGSET_XFP,
REGSET_IOPERM64 = REGSET_XFP,
REGSET_XSTATE,
REGSET_TLS,
REGSET_IOPERM32,
};
@ -1584,7 +1585,7 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
#ifdef CONFIG_X86_64
static const struct user_regset x86_64_regsets[] = {
static struct user_regset x86_64_regsets[] __read_mostly = {
[REGSET_GENERAL] = {
.core_note_type = NT_PRSTATUS,
.n = sizeof(struct user_regs_struct) / sizeof(long),
@ -1597,6 +1598,12 @@ static const struct user_regset x86_64_regsets[] = {
.size = sizeof(long), .align = sizeof(long),
.active = xfpregs_active, .get = xfpregs_get, .set = xfpregs_set
},
[REGSET_XSTATE] = {
.core_note_type = NT_X86_XSTATE,
.size = sizeof(u64), .align = sizeof(u64),
.active = xstateregs_active, .get = xstateregs_get,
.set = xstateregs_set
},
[REGSET_IOPERM64] = {
.core_note_type = NT_386_IOPERM,
.n = IO_BITMAP_LONGS,
@ -1622,7 +1629,7 @@ static const struct user_regset_view user_x86_64_view = {
#endif /* CONFIG_X86_64 */
#if defined CONFIG_X86_32 || defined CONFIG_IA32_EMULATION
static const struct user_regset x86_32_regsets[] = {
static struct user_regset x86_32_regsets[] __read_mostly = {
[REGSET_GENERAL] = {
.core_note_type = NT_PRSTATUS,
.n = sizeof(struct user_regs_struct32) / sizeof(u32),
@ -1641,6 +1648,12 @@ static const struct user_regset x86_32_regsets[] = {
.size = sizeof(u32), .align = sizeof(u32),
.active = xfpregs_active, .get = xfpregs_get, .set = xfpregs_set
},
[REGSET_XSTATE] = {
.core_note_type = NT_X86_XSTATE,
.size = sizeof(u64), .align = sizeof(u64),
.active = xstateregs_active, .get = xstateregs_get,
.set = xstateregs_set
},
[REGSET_TLS] = {
.core_note_type = NT_386_TLS,
.n = GDT_ENTRY_TLS_ENTRIES, .bias = GDT_ENTRY_TLS_MIN,
@ -1663,6 +1676,23 @@ static const struct user_regset_view user_x86_32_view = {
};
#endif
/*
* This represents bytes 464..511 in the memory layout exported through
* the REGSET_XSTATE interface.
*/
u64 xstate_fx_sw_bytes[USER_XSTATE_FX_SW_WORDS];
void update_regset_xstate_info(unsigned int size, u64 xstate_mask)
{
#ifdef CONFIG_X86_64
x86_64_regsets[REGSET_XSTATE].n = size / sizeof(u64);
#endif
#if defined CONFIG_X86_32 || defined CONFIG_IA32_EMULATION
x86_32_regsets[REGSET_XSTATE].n = size / sizeof(u64);
#endif
xstate_fx_sw_bytes[USER_XSTATE_XCR0_WORD] = xstate_mask;
}
const struct user_regset_view *task_user_regset_view(struct task_struct *task)
{
#ifdef CONFIG_IA32_EMULATION

1
arch/x86/kernel/xsave.c
View File

@ -337,6 +337,7 @@ void __ref xsave_cntxt_init(void)
cpuid_count(0xd, 0, &eax, &ebx, &ecx, &edx);
xstate_size = ebx;
update_regset_xstate_info(xstate_size, pcntxt_mask);
prepare_fx_sw_frame();
setup_xstate_init();

1
include/linux/elf.h
View File

@ -361,6 +361,7 @@ typedef struct elf64_shdr {
#define NT_PPC_VSX 0x102 /* PowerPC VSX registers */
#define NT_386_TLS 0x200 /* i386 TLS slots (struct user_desc) */
#define NT_386_IOPERM 0x201 /* x86 io permission bitmap (1=deny) */
#define NT_X86_XSTATE 0x202 /* x86 extended state using xsave */
#define NT_S390_HIGH_GPRS 0x300 /* s390 upper register halves */