Contributors: 29
| Author |
Tokens |
Token Proportion |
Commits |
Commit Proportion |
| Thomas Gleixner |
584 |
29.90% |
34 |
32.69% |
| Suresh B. Siddha |
453 |
23.20% |
8 |
7.69% |
| Ingo Molnar |
404 |
20.69% |
12 |
11.54% |
| Sebastian Andrzej Siewior |
143 |
7.32% |
10 |
9.62% |
| Chang S. Bae |
118 |
6.04% |
3 |
2.88% |
| Yu-cheng Yu |
52 |
2.66% |
5 |
4.81% |
| Rik Van Riel |
50 |
2.56% |
3 |
2.88% |
| Roland McGrath |
25 |
1.28% |
2 |
1.92% |
| Al Viro |
21 |
1.08% |
2 |
1.92% |
| Borislav Petkov |
16 |
0.82% |
1 |
0.96% |
| Linus Torvalds |
16 |
0.82% |
2 |
1.92% |
| Avi Kivity |
11 |
0.56% |
2 |
1.92% |
| Linus Torvalds (pre-git) |
8 |
0.41% |
1 |
0.96% |
| H. Peter Anvin |
7 |
0.36% |
1 |
0.96% |
| Andi Kleen |
7 |
0.36% |
2 |
1.92% |
| Hugh Dickins |
6 |
0.31% |
1 |
0.96% |
| Masahiro Yamada |
6 |
0.31% |
1 |
0.96% |
| Fenghua Yu |
5 |
0.26% |
2 |
1.92% |
| Dave Hansen |
5 |
0.26% |
2 |
1.92% |
| Andrew Lutomirski |
4 |
0.20% |
1 |
0.96% |
| Jann Horn |
3 |
0.15% |
1 |
0.96% |
| Marco Elver |
2 |
0.10% |
1 |
0.96% |
| Kyle Huey |
1 |
0.05% |
1 |
0.96% |
| Mathias Krause |
1 |
0.05% |
1 |
0.96% |
| Joe Perches |
1 |
0.05% |
1 |
0.96% |
| Andreas Gruenbacher |
1 |
0.05% |
1 |
0.96% |
| Eric Biggers |
1 |
0.05% |
1 |
0.96% |
| Anders Roxell |
1 |
0.05% |
1 |
0.96% |
| Greg Kroah-Hartman |
1 |
0.05% |
1 |
0.96% |
| Total |
1953 |
|
104 |
|
// SPDX-License-Identifier: GPL-2.0
/*
* FPU signal frame handling routines.
*/
#include <linux/compat.h>
#include <linux/cpu.h>
#include <linux/pagemap.h>
#include <asm/fpu/signal.h>
#include <asm/fpu/regset.h>
#include <asm/fpu/xstate.h>
#include <asm/sigframe.h>
#include <asm/trapnr.h>
#include <asm/trace/fpu.h>
#include "context.h"
#include "internal.h"
#include "legacy.h"
#include "xstate.h"
/*
* Check for the presence of extended state information in the
* user fpstate pointer in the sigcontext.
*/
static inline bool check_xstate_in_sigframe(struct fxregs_state __user *fxbuf,
struct _fpx_sw_bytes *fx_sw)
{
int min_xstate_size = sizeof(struct fxregs_state) +
sizeof(struct xstate_header);
void __user *fpstate = fxbuf;
unsigned int magic2;
if (__copy_from_user(fx_sw, &fxbuf->sw_reserved[0], sizeof(*fx_sw)))
return false;
/* 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 > current->thread.fpu.fpstate->user_size ||
fx_sw->xstate_size > fx_sw->extended_size)
goto setfx;
/*
* 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 (__get_user(magic2, (__u32 __user *)(fpstate + fx_sw->xstate_size)))
return false;
if (likely(magic2 == FP_XSTATE_MAGIC2))
return true;
setfx:
trace_x86_fpu_xstate_check_failed(¤t->thread.fpu);
/* Set the parameters for fx only state */
fx_sw->magic1 = 0;
fx_sw->xstate_size = sizeof(struct fxregs_state);
fx_sw->xfeatures = XFEATURE_MASK_FPSSE;
return true;
}
/*
* Signal frame handlers.
*/
static inline bool save_fsave_header(struct task_struct *tsk, void __user *buf)
{
if (use_fxsr()) {
struct xregs_state *xsave = &tsk->thread.fpu.fpstate->regs.xsave;
struct user_i387_ia32_struct env;
struct _fpstate_32 __user *fp = buf;
fpregs_lock();
if (!test_thread_flag(TIF_NEED_FPU_LOAD))
fxsave(&tsk->thread.fpu.fpstate->regs.fxsave);
fpregs_unlock();
convert_from_fxsr(&env, tsk);
if (__copy_to_user(buf, &env, sizeof(env)) ||
__put_user(xsave->i387.swd, &fp->status) ||
__put_user(X86_FXSR_MAGIC, &fp->magic))
return false;
} else {
struct fregs_state __user *fp = buf;
u32 swd;
if (__get_user(swd, &fp->swd) || __put_user(swd, &fp->status))
return false;
}
return true;
}
/*
* Prepare the SW reserved portion of the fxsave memory layout, indicating
* the presence of the extended state information in the memory layout
* pointed to by the fpstate pointer in the sigcontext.
* This is saved when ever the FP and extended state context is
* saved on the user stack during the signal handler delivery to the user.
*/
static inline void save_sw_bytes(struct _fpx_sw_bytes *sw_bytes, bool ia32_frame,
struct fpstate *fpstate)
{
sw_bytes->magic1 = FP_XSTATE_MAGIC1;
sw_bytes->extended_size = fpstate->user_size + FP_XSTATE_MAGIC2_SIZE;
sw_bytes->xfeatures = fpstate->user_xfeatures;
sw_bytes->xstate_size = fpstate->user_size;
if (ia32_frame)
sw_bytes->extended_size += sizeof(struct fregs_state);
}
static inline bool save_xstate_epilog(void __user *buf, int ia32_frame,
struct fpstate *fpstate)
{
struct xregs_state __user *x = buf;
struct _fpx_sw_bytes sw_bytes = {};
u32 xfeatures;
int err;
/* Setup the bytes not touched by the [f]xsave and reserved for SW. */
save_sw_bytes(&sw_bytes, ia32_frame, fpstate);
err = __copy_to_user(&x->i387.sw_reserved, &sw_bytes, sizeof(sw_bytes));
if (!use_xsave())
return !err;
err |= __put_user(FP_XSTATE_MAGIC2,
(__u32 __user *)(buf + fpstate->user_size));
/*
* Read the xfeatures which we copied (directly from the cpu or
* from the state in task struct) to the user buffers.
*/
err |= __get_user(xfeatures, (__u32 __user *)&x->header.xfeatures);
/*
* For legacy compatible, we always set FP/SSE bits in the bit
* vector while saving the state to the user context. This will
* enable us capturing any changes(during sigreturn) to
* the FP/SSE bits by the legacy applications which don't touch
* xfeatures in the xsave header.
*
* xsave aware apps can change the xfeatures in the xsave
* header as well as change any contents in the memory layout.
* xrestore as part of sigreturn will capture all the changes.
*/
xfeatures |= XFEATURE_MASK_FPSSE;
err |= __put_user(xfeatures, (__u32 __user *)&x->header.xfeatures);
return !err;
}
static inline int copy_fpregs_to_sigframe(struct xregs_state __user *buf)
{
if (use_xsave())
return xsave_to_user_sigframe(buf);
if (use_fxsr())
return fxsave_to_user_sigframe((struct fxregs_state __user *) buf);
else
return fnsave_to_user_sigframe((struct fregs_state __user *) buf);
}
/*
* Save the fpu, extended register state to the user signal frame.
*
* 'buf_fx' is the 64-byte aligned pointer at which the [f|fx|x]save
* state is copied.
* 'buf' points to the 'buf_fx' or to the fsave header followed by 'buf_fx'.
*
* buf == buf_fx for 64-bit frames and 32-bit fsave frame.
* buf != buf_fx for 32-bit frames with fxstate.
*
* Save it directly to the user frame with disabled page fault handler. If
* that faults, try to clear the frame which handles the page fault.
*
* If this is a 32-bit frame with fxstate, put a fsave header before
* the aligned state at 'buf_fx'.
*
* For [f]xsave state, update the SW reserved fields in the [f]xsave frame
* indicating the absence/presence of the extended state to the user.
*/
bool copy_fpstate_to_sigframe(void __user *buf, void __user *buf_fx, int size)
{
struct task_struct *tsk = current;
struct fpstate *fpstate = tsk->thread.fpu.fpstate;
bool ia32_fxstate = (buf != buf_fx);
int ret;
ia32_fxstate &= (IS_ENABLED(CONFIG_X86_32) ||
IS_ENABLED(CONFIG_IA32_EMULATION));
if (!static_cpu_has(X86_FEATURE_FPU)) {
struct user_i387_ia32_struct fp;
fpregs_soft_get(current, NULL, (struct membuf){.p = &fp,
.left = sizeof(fp)});
return !copy_to_user(buf, &fp, sizeof(fp));
}
if (!access_ok(buf, size))
return false;
if (use_xsave()) {
struct xregs_state __user *xbuf = buf_fx;
/*
* Clear the xsave header first, so that reserved fields are
* initialized to zero.
*/
if (__clear_user(&xbuf->header, sizeof(xbuf->header)))
return false;
}
retry:
/*
* Load the FPU registers if they are not valid for the current task.
* With a valid FPU state we can attempt to save the state directly to
* userland's stack frame which will likely succeed. If it does not,
* resolve the fault in the user memory and try again.
*/
fpregs_lock();
if (test_thread_flag(TIF_NEED_FPU_LOAD))
fpregs_restore_userregs();
pagefault_disable();
ret = copy_fpregs_to_sigframe(buf_fx);
pagefault_enable();
fpregs_unlock();
if (ret) {
if (!__clear_user(buf_fx, fpstate->user_size))
goto retry;
return false;
}
/* Save the fsave header for the 32-bit frames. */
if ((ia32_fxstate || !use_fxsr()) && !save_fsave_header(tsk, buf))
return false;
if (use_fxsr() && !save_xstate_epilog(buf_fx, ia32_fxstate, fpstate))
return false;
return true;
}
static int __restore_fpregs_from_user(void __user *buf, u64 ufeatures,
u64 xrestore, bool fx_only)
{
if (use_xsave()) {
u64 init_bv = ufeatures & ~xrestore;
int ret;
if (likely(!fx_only))
ret = xrstor_from_user_sigframe(buf, xrestore);
else
ret = fxrstor_from_user_sigframe(buf);
if (!ret && unlikely(init_bv))
os_xrstor(&init_fpstate, init_bv);
return ret;
} else if (use_fxsr()) {
return fxrstor_from_user_sigframe(buf);
} else {
return frstor_from_user_sigframe(buf);
}
}
/*
* Attempt to restore the FPU registers directly from user memory.
* Pagefaults are handled and any errors returned are fatal.
*/
static bool restore_fpregs_from_user(void __user *buf, u64 xrestore,
bool fx_only, unsigned int size)
{
struct fpu *fpu = ¤t->thread.fpu;
int ret;
retry:
fpregs_lock();
/* Ensure that XFD is up to date */
xfd_update_state(fpu->fpstate);
pagefault_disable();
ret = __restore_fpregs_from_user(buf, fpu->fpstate->user_xfeatures,
xrestore, fx_only);
pagefault_enable();
if (unlikely(ret)) {
/*
* The above did an FPU restore operation, restricted to
* the user portion of the registers, and failed, but the
* microcode might have modified the FPU registers
* nevertheless.
*
* If the FPU registers do not belong to current, then
* invalidate the FPU register state otherwise the task
* might preempt current and return to user space with
* corrupted FPU registers.
*/
if (test_thread_flag(TIF_NEED_FPU_LOAD))
__cpu_invalidate_fpregs_state();
fpregs_unlock();
/* Try to handle #PF, but anything else is fatal. */
if (ret != X86_TRAP_PF)
return false;
if (!fault_in_readable(buf, size))
goto retry;
return false;
}
/*
* Restore supervisor states: previous context switch etc has done
* XSAVES and saved the supervisor states in the kernel buffer from
* which they can be restored now.
*
* It would be optimal to handle this with a single XRSTORS, but
* this does not work because the rest of the FPU registers have
* been restored from a user buffer directly.
*/
if (test_thread_flag(TIF_NEED_FPU_LOAD) && xfeatures_mask_supervisor())
os_xrstor_supervisor(fpu->fpstate);
fpregs_mark_activate();
fpregs_unlock();
return true;
}
static bool __fpu_restore_sig(void __user *buf, void __user *buf_fx,
bool ia32_fxstate)
{
struct task_struct *tsk = current;
struct fpu *fpu = &tsk->thread.fpu;
struct user_i387_ia32_struct env;
bool success, fx_only = false;
union fpregs_state *fpregs;
unsigned int state_size;
u64 user_xfeatures = 0;
if (use_xsave()) {
struct _fpx_sw_bytes fx_sw_user;
if (!check_xstate_in_sigframe(buf_fx, &fx_sw_user))
return false;
fx_only = !fx_sw_user.magic1;
state_size = fx_sw_user.xstate_size;
user_xfeatures = fx_sw_user.xfeatures;
} else {
user_xfeatures = XFEATURE_MASK_FPSSE;
state_size = fpu->fpstate->user_size;
}
if (likely(!ia32_fxstate)) {
/* Restore the FPU registers directly from user memory. */
return restore_fpregs_from_user(buf_fx, user_xfeatures, fx_only,
state_size);
}
/*
* Copy the legacy state because the FP portion of the FX frame has
* to be ignored for histerical raisins. The legacy state is folded
* in once the larger state has been copied.
*/
if (__copy_from_user(&env, buf, sizeof(env)))
return false;
/*
* By setting TIF_NEED_FPU_LOAD it is ensured that our xstate is
* not modified on context switch and that the xstate is considered
* to be loaded again on return to userland (overriding last_cpu avoids
* the optimisation).
*/
fpregs_lock();
if (!test_thread_flag(TIF_NEED_FPU_LOAD)) {
/*
* If supervisor states are available then save the
* hardware state in current's fpstate so that the
* supervisor state is preserved. Save the full state for
* simplicity. There is no point in optimizing this by only
* saving the supervisor states and then shuffle them to
* the right place in memory. It's ia32 mode. Shrug.
*/
if (xfeatures_mask_supervisor())
os_xsave(fpu->fpstate);
set_thread_flag(TIF_NEED_FPU_LOAD);
}
__fpu_invalidate_fpregs_state(fpu);
__cpu_invalidate_fpregs_state();
fpregs_unlock();
fpregs = &fpu->fpstate->regs;
if (use_xsave() && !fx_only) {
if (copy_sigframe_from_user_to_xstate(tsk, buf_fx))
return false;
} else {
if (__copy_from_user(&fpregs->fxsave, buf_fx,
sizeof(fpregs->fxsave)))
return false;
if (IS_ENABLED(CONFIG_X86_64)) {
/* Reject invalid MXCSR values. */
if (fpregs->fxsave.mxcsr & ~mxcsr_feature_mask)
return false;
} else {
/* Mask invalid bits out for historical reasons (broken hardware). */
fpregs->fxsave.mxcsr &= mxcsr_feature_mask;
}
/* Enforce XFEATURE_MASK_FPSSE when XSAVE is enabled */
if (use_xsave())
fpregs->xsave.header.xfeatures |= XFEATURE_MASK_FPSSE;
}
/* Fold the legacy FP storage */
convert_to_fxsr(&fpregs->fxsave, &env);
fpregs_lock();
if (use_xsave()) {
/*
* Remove all UABI feature bits not set in user_xfeatures
* from the memory xstate header which makes the full
* restore below bring them into init state. This works for
* fx_only mode as well because that has only FP and SSE
* set in user_xfeatures.
*
* Preserve supervisor states!
*/
u64 mask = user_xfeatures | xfeatures_mask_supervisor();
fpregs->xsave.header.xfeatures &= mask;
success = !os_xrstor_safe(fpu->fpstate,
fpu_kernel_cfg.max_features);
} else {
success = !fxrstor_safe(&fpregs->fxsave);
}
if (likely(success))
fpregs_mark_activate();
fpregs_unlock();
return success;
}
static inline unsigned int xstate_sigframe_size(struct fpstate *fpstate)
{
unsigned int size = fpstate->user_size;
return use_xsave() ? size + FP_XSTATE_MAGIC2_SIZE : size;
}
/*
* Restore FPU state from a sigframe:
*/
bool fpu__restore_sig(void __user *buf, int ia32_frame)
{
struct fpu *fpu = ¤t->thread.fpu;
void __user *buf_fx = buf;
bool ia32_fxstate = false;
bool success = false;
unsigned int size;
if (unlikely(!buf)) {
fpu__clear_user_states(fpu);
return true;
}
size = xstate_sigframe_size(fpu->fpstate);
ia32_frame &= (IS_ENABLED(CONFIG_X86_32) ||
IS_ENABLED(CONFIG_IA32_EMULATION));
/*
* Only FXSR enabled systems need the FX state quirk.
* FRSTOR does not need it and can use the fast path.
*/
if (ia32_frame && use_fxsr()) {
buf_fx = buf + sizeof(struct fregs_state);
size += sizeof(struct fregs_state);
ia32_fxstate = true;
}
if (!access_ok(buf, size))
goto out;
if (!IS_ENABLED(CONFIG_X86_64) && !cpu_feature_enabled(X86_FEATURE_FPU)) {
success = !fpregs_soft_set(current, NULL, 0,
sizeof(struct user_i387_ia32_struct),
NULL, buf);
} else {
success = __fpu_restore_sig(buf, buf_fx, ia32_fxstate);
}
out:
if (unlikely(!success))
fpu__clear_user_states(fpu);
return success;
}
unsigned long
fpu__alloc_mathframe(unsigned long sp, int ia32_frame,
unsigned long *buf_fx, unsigned long *size)
{
unsigned long frame_size = xstate_sigframe_size(current->thread.fpu.fpstate);
*buf_fx = sp = round_down(sp - frame_size, 64);
if (ia32_frame && use_fxsr()) {
frame_size += sizeof(struct fregs_state);
sp -= sizeof(struct fregs_state);
}
*size = frame_size;
return sp;
}
unsigned long __init fpu__get_fpstate_size(void)
{
unsigned long ret = fpu_user_cfg.max_size;
if (use_xsave())
ret += FP_XSTATE_MAGIC2_SIZE;
/*
* This space is needed on (most) 32-bit kernels, or when a 32-bit
* app is running on a 64-bit kernel. To keep things simple, just
* assume the worst case and always include space for 'freg_state',
* even for 64-bit apps on 64-bit kernels. This wastes a bit of
* space, but keeps the code simple.
*/
if ((IS_ENABLED(CONFIG_IA32_EMULATION) ||
IS_ENABLED(CONFIG_X86_32)) && use_fxsr())
ret += sizeof(struct fregs_state);
return ret;
}