Commit 91c3dba7 authored by Yu-cheng Yu's avatar Yu-cheng Yu Committed by Ingo Molnar

x86/fpu/xstate: Fix PTRACE frames for XSAVES

XSAVES uses compacted format and is a kernel instruction. The kernel
should use standard-format, non-supervisor state data for PTRACE.
Signed-off-by: default avatarYu-cheng Yu <yu-cheng.yu@intel.com>
[ Edited away artificial linebreaks. ]
Reviewed-by: default avatarDave 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: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.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/de3d80949001305fe389799973b675cab055c457.1466179491.git.yu-cheng.yu@intel.com
[ Made various readability edits. ]
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 1499ce2d
......@@ -51,5 +51,8 @@ void fpu__xstate_clear_all_cpu_caps(void);
void *get_xsave_addr(struct xregs_state *xsave, int xstate);
const void *get_xsave_field_ptr(int xstate_field);
int using_compacted_format(void);
int copyout_from_xsaves(unsigned int pos, unsigned int count, void *kbuf,
void __user *ubuf, struct xregs_state *xsave);
int copyin_to_xsaves(const void *kbuf, const void __user *ubuf,
struct xregs_state *xsave);
#endif
......@@ -4,6 +4,7 @@
#include <asm/fpu/internal.h>
#include <asm/fpu/signal.h>
#include <asm/fpu/regset.h>
#include <asm/fpu/xstate.h>
/*
* The xstateregs_active() routine is the same as the regset_fpregs_active() routine,
......@@ -85,21 +86,26 @@ int xstateregs_get(struct task_struct *target, const struct user_regset *regset,
if (!boot_cpu_has(X86_FEATURE_XSAVE))
return -ENODEV;
fpu__activate_fpstate_read(fpu);
xsave = &fpu->state.xsave;
/*
* Copy the 48bytes defined by the software first into the xstate
* memory layout in the thread struct, so that we can copy the entire
* xstateregs to the user using one user_regset_copyout().
*/
memcpy(&xsave->i387.sw_reserved,
xstate_fx_sw_bytes, sizeof(xstate_fx_sw_bytes));
/*
* Copy the xstate memory layout.
*/
ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, xsave, 0, -1);
fpu__activate_fpstate_read(fpu);
if (using_compacted_format()) {
ret = copyout_from_xsaves(pos, count, kbuf, ubuf, xsave);
} else {
fpstate_sanitize_xstate(fpu);
/*
* Copy the 48 bytes defined by the software into the xsave
* area in the thread struct, so that we can copy the whole
* area to user using one user_regset_copyout().
*/
memcpy(&xsave->i387.sw_reserved, xstate_fx_sw_bytes, sizeof(xstate_fx_sw_bytes));
/*
* Copy the xstate memory layout.
*/
ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, xsave, 0, -1);
}
return ret;
}
......@@ -114,11 +120,27 @@ int xstateregs_set(struct task_struct *target, const struct user_regset *regset,
if (!boot_cpu_has(X86_FEATURE_XSAVE))
return -ENODEV;
fpu__activate_fpstate_write(fpu);
/*
* A whole standard-format XSAVE buffer is needed:
*/
if ((pos != 0) || (count < fpu_user_xstate_size))
return -EFAULT;
xsave = &fpu->state.xsave;
ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, xsave, 0, -1);
fpu__activate_fpstate_write(fpu);
if (boot_cpu_has(X86_FEATURE_XSAVES))
ret = copyin_to_xsaves(kbuf, ubuf, xsave);
else
ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, xsave, 0, -1);
/*
* In case of failure, mark all states as init:
*/
if (ret)
fpstate_init(&fpu->state);
/*
* mxcsr reserved bits must be masked to zero for security reasons.
*/
......
......@@ -11,6 +11,7 @@
#include <asm/fpu/internal.h>
#include <asm/fpu/signal.h>
#include <asm/fpu/regset.h>
#include <asm/fpu/xstate.h>
#include <asm/tlbflush.h>
......@@ -697,7 +698,12 @@ void __init fpu__init_system_xstate(void)
return;
}
update_regset_xstate_info(fpu_kernel_xstate_size, xfeatures_mask);
/*
* 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);
fpu__init_prepare_fx_sw_frame();
setup_init_fpu_buf();
setup_xstate_comp();
......@@ -925,16 +931,16 @@ int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
if (!boot_cpu_has(X86_FEATURE_OSPKE))
return -EINVAL;
/* Set the bits we need in PKRU */
/* Set the bits we need in PKRU: */
if (init_val & PKEY_DISABLE_ACCESS)
new_pkru_bits |= PKRU_AD_BIT;
if (init_val & PKEY_DISABLE_WRITE)
new_pkru_bits |= PKRU_WD_BIT;
/* Shift the bits in to the correct place in PKRU for pkey. */
/* Shift the bits in to the correct place in PKRU for pkey: */
new_pkru_bits <<= pkey_shift;
/* Locate old copy of the state in the xsave buffer */
/* Locate old copy of the state in the xsave buffer: */
old_pkru_state = get_xsave_addr(xsave, XFEATURE_MASK_PKRU);
/*
......@@ -947,9 +953,10 @@ int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
else
new_pkru_state.pkru = old_pkru_state->pkru;
/* mask off any old bits in place */
/* Mask off any old bits in place: */
new_pkru_state.pkru &= ~((PKRU_AD_BIT|PKRU_WD_BIT) << pkey_shift);
/* Set the newly-requested bits */
/* Set the newly-requested bits: */
new_pkru_state.pkru |= new_pkru_bits;
/*
......@@ -963,8 +970,168 @@ int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
*/
new_pkru_state.pad = 0;
fpu__xfeature_set_state(XFEATURE_MASK_PKRU, &new_pkru_state,
sizeof(new_pkru_state));
fpu__xfeature_set_state(XFEATURE_MASK_PKRU, &new_pkru_state, sizeof(new_pkru_state));
return 0;
}
/*
* This is similar to user_regset_copyout(), but will not add offset to
* the source data pointer or increment pos, count, kbuf, and ubuf.
*/
static inline int xstate_copyout(unsigned int pos, unsigned int count,
void *kbuf, void __user *ubuf,
const void *data, const int start_pos,
const int end_pos)
{
if ((count == 0) || (pos < start_pos))
return 0;
if (end_pos < 0 || pos < end_pos) {
unsigned int copy = (end_pos < 0 ? count : min(count, end_pos - pos));
if (kbuf) {
memcpy(kbuf + pos, data, copy);
} else {
if (__copy_to_user(ubuf + pos, data, copy))
return -EFAULT;
}
}
return 0;
}
/*
* Convert from kernel XSAVES compacted format to standard format and copy
* to a ptrace buffer. It supports partial copy but pos always starts from
* zero. This is called from xstateregs_get() and there we check the CPU
* has XSAVES.
*/
int copyout_from_xsaves(unsigned int pos, unsigned int count, void *kbuf,
void __user *ubuf, struct xregs_state *xsave)
{
unsigned int offset, size;
int ret, i;
struct xstate_header header;
/*
* Currently copy_regset_to_user() starts from pos 0:
*/
if (unlikely(pos != 0))
return -EFAULT;
/*
* The destination is a ptrace buffer; we put in only user xstates:
*/
memset(&header, 0, sizeof(header));
header.xfeatures = xsave->header.xfeatures;
header.xfeatures &= ~XFEATURE_MASK_SUPERVISOR;
/*
* Copy xregs_state->header:
*/
offset = offsetof(struct xregs_state, header);
size = sizeof(header);
ret = xstate_copyout(offset, size, kbuf, ubuf, &header, 0, count);
if (ret)
return ret;
for (i = 0; i < XFEATURE_MAX; i++) {
/*
* Copy only in-use xstates:
*/
if ((header.xfeatures >> i) & 1) {
void *src = __raw_xsave_addr(xsave, 1 << i);
offset = xstate_offsets[i];
size = xstate_sizes[i];
ret = xstate_copyout(offset, size, kbuf, ubuf, src, 0, count);
if (ret)
return ret;
if (offset + size >= count)
break;
}
}
/*
* Fill xsave->i387.sw_reserved value for ptrace frame:
*/
offset = offsetof(struct fxregs_state, sw_reserved);
size = sizeof(xstate_fx_sw_bytes);
ret = xstate_copyout(offset, size, kbuf, ubuf, xstate_fx_sw_bytes, 0, count);
if (ret)
return ret;
return 0;
}
/*
* Convert from a ptrace standard-format buffer to kernel XSAVES format
* and copy to the target thread. This is called from xstateregs_set() and
* there we check the CPU has XSAVES and a whole standard-sized buffer
* exists.
*/
int copyin_to_xsaves(const void *kbuf, const void __user *ubuf,
struct xregs_state *xsave)
{
unsigned int offset, size;
int i;
u64 xfeatures;
u64 allowed_features;
offset = offsetof(struct xregs_state, header);
size = sizeof(xfeatures);
if (kbuf) {
memcpy(&xfeatures, kbuf + offset, size);
} else {
if (__copy_from_user(&xfeatures, ubuf + offset, size))
return -EFAULT;
}
/*
* Reject if the user sets any disabled or supervisor features:
*/
allowed_features = xfeatures_mask & ~XFEATURE_MASK_SUPERVISOR;
if (xfeatures & ~allowed_features)
return -EINVAL;
for (i = 0; i < XFEATURE_MAX; i++) {
u64 mask = ((u64)1 << i);
if (xfeatures & mask) {
void *dst = __raw_xsave_addr(xsave, 1 << i);
offset = xstate_offsets[i];
size = xstate_sizes[i];
if (kbuf) {
memcpy(dst, kbuf + offset, size);
} else {
if (__copy_from_user(dst, ubuf + offset, size))
return -EFAULT;
}
}
}
/*
* 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;
/*
* Add back in the features that came in from userspace:
*/
xsave->header.xfeatures |= xfeatures;
return 0;
}
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