Messages in this thread Patch in this message | | | From | "Chang S. Bae" <> | Subject | [PATCH v3 12/21] x86/fpu/xstate: Update xstate context copy function to support dynamic buffer | Date | Wed, 23 Dec 2020 07:57:08 -0800 |
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ptrace() and signal return paths use xstate context copy functions. They allow callers to read (or write) xstate values in the target's buffer. With dynamic user states, a component's position in the buffer may vary and the initial value is not always stored in init_fpstate.
Change the helpers to find a component's offset accordingly.
When copying an initial value, explicitly check the init_fpstate coverage. If not found, reset the memory in the destination. Otherwise, copy values from init_fpstate.
No functional change until the kernel supports dynamic user states.
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com> Reviewed-by: Len Brown <len.brown@intel.com> Cc: x86@kernel.org Cc: linux-kernel@vger.kernel.org --- Changes from v2: * Updated the changelog with task->fpu removed. (Boris Petkov) --- arch/x86/kernel/fpu/xstate.c | 55 +++++++++++++++++++++++++++--------- 1 file changed, 41 insertions(+), 14 deletions(-)
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index 6b863b2ca405..1d7d0cce6cc5 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -248,12 +248,14 @@ void fpstate_sanitize_xstate(struct fpu *fpu) if (!(xfeatures & XFEATURE_MASK_SSE)) memset(&fx->xmm_space[0], 0, 256); + /* Make sure 'xfeatures' to be a subset of fpu->state_mask */ + xfeatures = ((xfeatures_mask_user() & fpu->state_mask) & ~xfeatures); /* * First two features are FPU and SSE, which above we handled * in a special way already: */ feature_bit = 0x2; - xfeatures = (xfeatures_mask_user() & ~xfeatures) >> 2; + xfeatures >>= 0x2; /* * Update all the remaining memory layouts according to their @@ -262,12 +264,15 @@ void fpstate_sanitize_xstate(struct fpu *fpu) */ while (xfeatures) { if (xfeatures & 0x1) { - int offset = xstate_comp_offsets[feature_bit]; - int size = xstate_sizes[feature_bit]; - - memcpy((void *)xsave + offset, - (void *)&init_fpstate.xsave + offset, - size); + unsigned int offset = get_xstate_comp_offset(fpu, feature_bit); + unsigned int size = xstate_sizes[feature_bit]; + + if (get_init_fpstate_mask() & BIT_ULL(feature_bit)) + memcpy((void *)xsave + offset, + (void *)&init_fpstate.xsave + offset, + size); + else + memset((void *)xsave + offset, 0, size); } xfeatures >>= 1; @@ -1232,7 +1237,10 @@ static void fill_gap(struct membuf *to, unsigned *last, unsigned offset) { if (*last >= offset) return; - membuf_write(to, (void *)&init_fpstate.xsave + *last, offset - *last); + if (offset <= get_init_fpstate_size()) + membuf_write(to, (void *)&init_fpstate.xsave + *last, offset - *last); + else + membuf_zero(to, offset - *last); *last = offset; } @@ -1240,7 +1248,10 @@ static void copy_part(struct membuf *to, unsigned *last, unsigned offset, unsigned size, void *from) { fill_gap(to, last, offset); - membuf_write(to, from, size); + if (from) + membuf_write(to, from, size); + else + membuf_zero(to, size); *last = offset + size; } @@ -1292,12 +1303,22 @@ void copy_xstate_to_kernel(struct membuf to, struct fpu *fpu) sizeof(header), &header); for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) { + u64 mask = BIT_ULL(i); + void *src; /* - * Copy only in-use xstates: + * Copy only in-use xstate at first. If the feature is enabled, + * find the init value, whether stored in init_fpstate or simply + * zeros, and then copy them. */ - if ((header.xfeatures >> i) & 1) { - void *src = __raw_xsave_addr(fpu, i); - + if (header.xfeatures & mask) { + src = __raw_xsave_addr(fpu, i); + copy_part(&to, &last, xstate_offsets[i], + xstate_sizes[i], src); + } else if (xfeatures_mask_user() & mask) { + if (get_init_fpstate_mask() & mask) + src = (void *)&init_fpstate.xsave + last; + else + src = NULL; copy_part(&to, &last, xstate_offsets[i], xstate_sizes[i], src); } @@ -1331,6 +1352,9 @@ int copy_kernel_to_xstate(struct fpu *fpu, const void *kbuf) if (hdr.xfeatures & mask) { void *dst = __raw_xsave_addr(fpu, i); + if (!dst) + continue; + offset = xstate_offsets[i]; size = xstate_sizes[i]; @@ -1388,6 +1412,9 @@ int copy_user_to_xstate(struct fpu *fpu, const void __user *ubuf) if (hdr.xfeatures & mask) { void *dst = __raw_xsave_addr(fpu, i); + if (!dst) + continue; + offset = xstate_offsets[i]; size = xstate_sizes[i]; @@ -1470,7 +1497,7 @@ void copy_supervisor_to_kernel(struct fpu *fpu) continue; /* Move xfeature 'i' into its normal location */ - memmove(xbuf + xstate_comp_offsets[i], + memmove(xbuf + get_xstate_comp_offset(fpu, i), xbuf + xstate_supervisor_only_offsets[i], xstate_sizes[i]); } -- 2.17.1
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