Messages in this thread Patch in this message | | | From | "Chang S. Bae" <> | Subject | [PATCH v9 11/26] x86/fpu/xstate: Update the XSTATE context copy function to support dynamic states | Date | Fri, 30 Jul 2021 07:59:42 -0700 |
| |
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 init fpstate is not always large enough to cover all the states.
Adjust the helpers to find a component's offset correctly. Also, update the copy loop in the ptrace read path to support dynamic 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 v5: * Updated to ensure xstate_bv aligned with the target. * Rewrote the xstate copy loop, for the ptrace() read path, in an open code. * Adjusted the changelog.
Changes from v3: * Cleaned up the code change with more comments. * Removed 'no functional change' in the changelog. (Borislav Petkov)
Changes from v2: * Updated the changelog with task->fpu removed. (Borislav Petkov) --- arch/x86/kernel/fpu/xstate.c | 30 +++++++++++++++++++++++++----- 1 file changed, 25 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index 98ab10e4da3b..3b56e7612c45 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -1273,6 +1273,7 @@ void copy_xstate_to_uabi_buf(struct membuf to, struct task_struct *tsk, zerofrom = offsetof(struct xregs_state, extended_state_area); for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) { + u64 mask = BIT_ULL(i); /* * The ptrace buffer is in non-compacted XSAVE format. * In non-compacted format disabled features still occupy @@ -1280,7 +1281,7 @@ void copy_xstate_to_uabi_buf(struct membuf to, struct task_struct *tsk, * compacted init_fpstate. The gap tracking will zero this * later. */ - if (!(xfeatures_mask_uabi() & BIT_ULL(i))) + if (!(xfeatures_mask_uabi() & mask)) continue; /* @@ -1300,10 +1301,24 @@ void copy_xstate_to_uabi_buf(struct membuf to, struct task_struct *tsk, pkru.pkru = tsk->thread.pkru; membuf_write(&to, &pkru, sizeof(pkru)); } else { - copy_feature(header.xfeatures & BIT_ULL(i), &to, - __raw_xsave_addr(&tsk->thread.fpu, i), - __raw_xsave_addr(NULL, i), - xstate_sizes[i]); + unsigned int size = xstate_sizes[i]; + void *from = NULL; + + /* + * Copy the xstate if available. Otherwise, copy the + * non-zero init states for legacy states (FP and + * SSE) or fill zeros. + */ + + if (header.xfeatures & mask) + from = __raw_xsave_addr(&tsk->thread.fpu, i); + else if (XFEATURE_MASK_FPSSE & mask) + from = __raw_xsave_addr(NULL, i); + + if (from) + membuf_write(&to, from, size); + else + membuf_zero(&to, size); } /* * Keep track of the last copied state in the non-compacted @@ -1345,6 +1360,8 @@ static int copy_uabi_to_xstate(struct fpu *fpu, const void *kbuf, if (validate_user_xstate_header(&hdr)) return -EINVAL; + hdr.xfeatures &= fpu->state_mask; + /* 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) { @@ -1371,6 +1388,9 @@ static int copy_uabi_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]; -- 2.17.1
| |