Messages in this thread Patch in this message | | | From | Yu-cheng Yu <> | Subject | [PATCH 3/5] x86/fpu/xstate: Fix PTRACE frames for XSAVES | Date | Fri, 17 Jun 2016 13:07:17 -0700 |
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XSAVES uses compacted format and is a kernel instruction. The kernel should use standard-format, non-supervisor state data for PTRACE.
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com> Reviewed-by: Dave Hansen <dave.hansen@intel.com> --- arch/x86/include/asm/fpu/xstate.h | 5 +- arch/x86/kernel/fpu/regset.c | 55 +++++++++---- arch/x86/kernel/fpu/xstate.c | 167 +++++++++++++++++++++++++++++++++++++- 3 files changed, 210 insertions(+), 17 deletions(-)
diff --git a/arch/x86/include/asm/fpu/xstate.h b/arch/x86/include/asm/fpu/xstate.h index 92f376c..ae55a43 100644 --- a/arch/x86/include/asm/fpu/xstate.h +++ b/arch/x86/include/asm/fpu/xstate.h @@ -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 diff --git a/arch/x86/kernel/fpu/regset.c b/arch/x86/kernel/fpu/regset.c index 81422df..5248491 100644 --- a/arch/x86/kernel/fpu/regset.c +++ b/arch/x86/kernel/fpu/regset.c @@ -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 +86,28 @@ 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 +122,28 @@ 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. */ diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index ec7e53b..8d5fb03 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -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 +698,13 @@ 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(); @@ -968,3 +975,161 @@ int arch_set_user_pkey_access(struct task_struct *tsk, int pkey, 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; +} -- 1.9.1
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