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Subject[PATCH 11/33] x86/fpu: Split copy_user_to_xstate() into copy_kernel_to_xstate() & copy_user_to_xstate()
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x86/fpu: Split copy_xstate_to_user() into copy_xstate_to_kernel() & copy_xstate_to_user()

No change in functionality.

Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.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: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/include/asm/fpu/xstate.h | 4 ++--
arch/x86/kernel/fpu/regset.c | 10 ++++++---
arch/x86/kernel/fpu/xstate.c | 66 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
3 files changed, 74 insertions(+), 6 deletions(-)

diff --git a/arch/x86/include/asm/fpu/xstate.h b/arch/x86/include/asm/fpu/xstate.h
index fed6617a1079..79af79dbcab6 100644
--- a/arch/x86/include/asm/fpu/xstate.h
+++ b/arch/x86/include/asm/fpu/xstate.h
@@ -50,6 +50,6 @@ const void *get_xsave_field_ptr(int xstate_field);
int using_compacted_format(void);
int copy_xstate_to_kernel(void *kbuf, struct xregs_state *xsave, unsigned int offset, unsigned int size);
int copy_xstate_to_user(void __user *ubuf, struct xregs_state *xsave, unsigned int offset, unsigned int size);
-int copy_user_to_xstate(const void *kbuf, const void __user *ubuf,
- struct xregs_state *xsave);
+int copy_kernel_to_xstate(const void *kbuf, const void __user *ubuf, struct xregs_state *xsave);
+int copy_user_to_xstate(const void *kbuf, const void __user *ubuf, struct xregs_state *xsave);
#endif
diff --git a/arch/x86/kernel/fpu/regset.c b/arch/x86/kernel/fpu/regset.c
index ec1404194b65..cb45dd81d617 100644
--- a/arch/x86/kernel/fpu/regset.c
+++ b/arch/x86/kernel/fpu/regset.c
@@ -134,10 +134,14 @@ int xstateregs_set(struct task_struct *target, const struct user_regset *regset,

fpu__activate_fpstate_write(fpu);

- if (boot_cpu_has(X86_FEATURE_XSAVES))
- ret = copy_user_to_xstate(kbuf, ubuf, xsave);
- else
+ if (boot_cpu_has(X86_FEATURE_XSAVES)) {
+ if (kbuf)
+ ret = copy_kernel_to_xstate(kbuf, ubuf, xsave);
+ else
+ ret = copy_user_to_xstate(kbuf, ubuf, xsave);
+ } else {
ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, xsave, 0, -1);
+ }

/*
* In case of failure, mark all states as init:
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index 00c3b41c3cf1..1ad25d1b8056 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -1084,7 +1084,71 @@ int copy_xstate_to_user(void __user *ubuf, struct xregs_state *xsave, unsigned i
}

/*
- * Convert from a ptrace standard-format buffer to kernel XSAVES format
+ * Convert from a ptrace standard-format kernel 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 copy_kernel_to_xstate(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;
+}
+
+/*
+ * Convert from a ptrace standard-format user-space 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.
--
2.11.0
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