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    Subject[patch V3 32/66] x86/fpu: Deduplicate copy_uabi_from_user/kernel_to_xstate()
    copy_uabi_from_user_to_xstate() and copy_uabi_from_kernel_to_xstate() are
    almost identical except for the copy function.

    Unify them.

    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    Acked-by: Andy Lutomirski <luto@kernel.org>
    ---
    V3: Fixed MXCSR thinkos and simplified the handling of MXCSR
    ---
    arch/x86/kernel/fpu/xstate.c | 137 ++++++++++++++-----------------------------
    1 file changed, 47 insertions(+), 90 deletions(-)

    --- a/arch/x86/kernel/fpu/xstate.c
    +++ b/arch/x86/kernel/fpu/xstate.c
    @@ -953,23 +953,6 @@ int arch_set_user_pkey_access(struct tas
    }
    #endif /* ! CONFIG_ARCH_HAS_PKEYS */

    -/*
    - * Weird legacy quirk: SSE and YMM states store information in the
    - * MXCSR and MXCSR_FLAGS fields of the FP area. That means if the FP
    - * area is marked as unused in the xfeatures header, we need to copy
    - * MXCSR and MXCSR_FLAGS if either SSE or YMM are in use.
    - */
    -static inline bool xfeatures_mxcsr_quirk(u64 xfeatures)
    -{
    - if (!(xfeatures & (XFEATURE_MASK_SSE|XFEATURE_MASK_YMM)))
    - return false;
    -
    - if (xfeatures & XFEATURE_MASK_FP)
    - return false;
    -
    - return true;
    -}
    -
    static void copy_feature(bool from_xstate, struct membuf *to, void *xstate,
    void *init_xstate, unsigned int size)
    {
    @@ -1082,39 +1065,53 @@ void copy_xstate_to_uabi_buf(struct memb
    membuf_zero(&to, to.left);
    }

    -static inline bool mxcsr_valid(struct xstate_header *hdr, const u32 *mxcsr)
    +static int copy_from_buffer(void *dst, unsigned int offset, unsigned int size,
    + const void *kbuf, const void __user *ubuf)
    {
    - u64 mask = XFEATURE_MASK_FP | XFEATURE_MASK_SSE | XFEATURE_MASK_YMM;
    -
    - /* Only check if it is in use */
    - if (hdr->xfeatures & mask) {
    - /* Reserved bits in MXCSR must be zero. */
    - if (*mxcsr & ~mxcsr_feature_mask)
    - return false;
    + if (kbuf) {
    + memcpy(dst, kbuf + offset, size);
    + } else {
    + if (copy_from_user(dst, ubuf + offset, size))
    + return -EFAULT;
    }
    - return true;
    + return 0;
    }

    -/*
    - * Convert from a ptrace standard-format kernel buffer to kernel XSAVE[S] format
    - * and copy to the target thread. This is called from xstateregs_set().
    - */
    -int copy_uabi_from_kernel_to_xstate(struct xregs_state *xsave, const void *kbuf)
    +
    +static int copy_uabi_to_xstate(struct xregs_state *xsave, const void *kbuf,
    + const void __user *ubuf)
    {
    unsigned int offset, size;
    - int i;
    struct xstate_header hdr;
    + u64 mask;
    + int i;

    offset = offsetof(struct xregs_state, header);
    - size = sizeof(hdr);
    -
    - memcpy(&hdr, kbuf + offset, size);
    + if (copy_from_buffer(&hdr, offset, sizeof(hdr), kbuf, ubuf))
    + return -EFAULT;

    if (validate_user_xstate_header(&hdr))
    return -EINVAL;

    - if (!mxcsr_valid(&hdr, kbuf + offsetof(struct fxregs_state, mxcsr)))
    - return -EINVAL;
    + /* Validate MXCSR when any of the related features is in use */
    + mask = XFEATURE_MASK_FP | XFEATURE_MASK_SSE | XFEATURE_MASK_YMM;
    + if (hdr.xfeatures & mask) {
    + u32 mxcsr[2];
    +
    + offset = offsetof(struct fxregs_state, mxcsr);
    + if (copy_from_buffer(mxcsr, offset, sizeof(mxcsr), kbuf, ubuf))
    + return -EFAULT;
    +
    + /* Reserved bits in MXCSR must be zero. */
    + if (mxcsr[0] & ~mxcsr_feature_mask)
    + return -EINVAL;
    +
    + /* SSE and YMM require MXCSR even when FP is not in use. */
    + if (!(hdr.xfeatures & XFEATURE_MASK_FP)) {
    + xsave->i387.mxcsr = mxcsr[0];
    + xsave->i387.mxcsr_mask = mxcsr[1];
    + }
    + }

    for (i = 0; i < XFEATURE_MAX; i++) {
    u64 mask = ((u64)1 << i);
    @@ -1125,16 +1122,11 @@ int copy_uabi_from_kernel_to_xstate(stru
    offset = xstate_offsets[i];
    size = xstate_sizes[i];

    - memcpy(dst, kbuf + offset, size);
    + if (copy_from_buffer(dst, offset, size, kbuf, ubuf))
    + return -EFAULT;
    }
    }

    - if (xfeatures_mxcsr_quirk(hdr.xfeatures)) {
    - offset = offsetof(struct fxregs_state, mxcsr);
    - size = MXCSR_AND_FLAGS_SIZE;
    - memcpy(&xsave->i387.mxcsr, kbuf + offset, size);
    - }
    -
    /*
    * The state that came in from userspace was user-state only.
    * Mask all the user states out of 'xfeatures':
    @@ -1150,6 +1142,16 @@ int copy_uabi_from_kernel_to_xstate(stru
    }

    /*
    + * Convert from a ptrace standard-format kernel buffer to kernel XSAVE[S]
    + * format and copy to the target thread. This is called from
    + * xstateregs_set().
    + */
    +int copy_uabi_from_kernel_to_xstate(struct xregs_state *xsave, const void *kbuf)
    +{
    + return copy_uabi_to_xstate(xsave, kbuf, NULL);
    +}
    +
    +/*
    * Convert from a sigreturn standard-format user-space buffer to kernel
    * XSAVE[S] format and copy to the target thread. This is called from the
    * sigreturn() and rt_sigreturn() system calls.
    @@ -1157,52 +1159,7 @@ int copy_uabi_from_kernel_to_xstate(stru
    int copy_sigframe_from_user_to_xstate(struct xregs_state *xsave,
    const void __user *ubuf)
    {
    - unsigned int offset, size;
    - int i;
    - struct xstate_header hdr;
    -
    - offset = offsetof(struct xregs_state, header);
    - size = sizeof(hdr);
    -
    - if (copy_from_user(&hdr, ubuf + offset, size))
    - return -EFAULT;
    -
    - if (validate_user_xstate_header(&hdr))
    - return -EINVAL;
    -
    - for (i = 0; i < XFEATURE_MAX; i++) {
    - u64 mask = ((u64)1 << i);
    -
    - if (hdr.xfeatures & mask) {
    - void *dst = __raw_xsave_addr(xsave, i);
    -
    - offset = xstate_offsets[i];
    - size = xstate_sizes[i];
    -
    - if (copy_from_user(dst, ubuf + offset, size))
    - return -EFAULT;
    - }
    - }
    -
    - if (xfeatures_mxcsr_quirk(hdr.xfeatures)) {
    - offset = offsetof(struct fxregs_state, mxcsr);
    - size = MXCSR_AND_FLAGS_SIZE;
    - if (copy_from_user(&xsave->i387.mxcsr, 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_ALL;
    -
    - /*
    - * Add back in the features that came in from userspace:
    - */
    - xsave->header.xfeatures |= hdr.xfeatures;
    -
    - return 0;
    + return copy_uabi_to_xstate(xsave, NULL, ubuf);
    }

    /**
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