diff options
| -rw-r--r-- | arch/x86/include/asm/fpu/xstate.h | 1 | ||||
| -rw-r--r-- | arch/x86/kernel/fpu/xstate.c | 84 |
2 files changed, 85 insertions, 0 deletions
diff --git a/arch/x86/include/asm/fpu/xstate.h b/arch/x86/include/asm/fpu/xstate.h index 92104b298d77..422d8369012a 100644 --- a/arch/x86/include/asm/fpu/xstate.h +++ b/arch/x86/include/asm/fpu/xstate.h @@ -75,6 +75,7 @@ int copy_xstate_to_kernel(void *kbuf, struct xregs_state *xsave, unsigned int of int copy_xstate_to_user(void __user *ubuf, struct xregs_state *xsave, unsigned int offset, unsigned int size); int copy_kernel_to_xstate(struct xregs_state *xsave, const void *kbuf); int copy_user_to_xstate(struct xregs_state *xsave, const void __user *ubuf); +void copy_supervisor_to_kernel(struct xregs_state *xsave); /* Validate an xstate header supplied by userspace (ptrace or sigreturn) */ int validate_user_xstate_header(const struct xstate_header *hdr); diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index a68213ed5be6..587e03f0094d 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -62,6 +62,7 @@ u64 xfeatures_mask_all __read_mostly; static unsigned int xstate_offsets[XFEATURE_MAX] = { [ 0 ... XFEATURE_MAX - 1] = -1}; static unsigned int xstate_sizes[XFEATURE_MAX] = { [ 0 ... XFEATURE_MAX - 1] = -1}; static unsigned int xstate_comp_offsets[XFEATURE_MAX] = { [ 0 ... XFEATURE_MAX - 1] = -1}; +static unsigned int xstate_supervisor_only_offsets[XFEATURE_MAX] = { [ 0 ... XFEATURE_MAX - 1] = -1}; /* * The XSAVE area of kernel can be in standard or compacted format; @@ -393,6 +394,33 @@ static void __init setup_xstate_comp_offsets(void) } /* + * Setup offsets of a supervisor-state-only XSAVES buffer: + * + * The offsets stored in xstate_comp_offsets[] only work for one specific + * value of the Requested Feature BitMap (RFBM). In cases where a different + * RFBM value is used, a different set of offsets is required. This set of + * offsets is for when RFBM=xfeatures_mask_supervisor(). + */ +static void __init setup_supervisor_only_offsets(void) +{ + unsigned int next_offset; + int i; + + next_offset = FXSAVE_SIZE + XSAVE_HDR_SIZE; + + for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) { + if (!xfeature_enabled(i) || !xfeature_is_supervisor(i)) + continue; + + if (xfeature_is_aligned(i)) + next_offset = ALIGN(next_offset, 64); + + xstate_supervisor_only_offsets[i] = next_offset; + next_offset += xstate_sizes[i]; + } +} + +/* * Print out xstate component offsets and sizes */ static void __init print_xstate_offset_size(void) @@ -790,6 +818,7 @@ void __init fpu__init_system_xstate(void) fpu__init_prepare_fx_sw_frame(); setup_init_fpu_buf(); setup_xstate_comp_offsets(); + setup_supervisor_only_offsets(); print_xstate_offset_size(); pr_info("x86/fpu: Enabled xstate features 0x%llx, context size is %d bytes, using '%s' format.\n", @@ -1262,6 +1291,61 @@ int copy_user_to_xstate(struct xregs_state *xsave, const void __user *ubuf) return 0; } +/* + * Save only supervisor states to the kernel buffer. This blows away all + * old states, and is intended to be used only in __fpu__restore_sig(), where + * user states are restored from the user buffer. + */ +void copy_supervisor_to_kernel(struct xregs_state *xstate) +{ + struct xstate_header *header; + u64 max_bit, min_bit; + u32 lmask, hmask; + int err, i; + + if (WARN_ON(!boot_cpu_has(X86_FEATURE_XSAVES))) + return; + + if (!xfeatures_mask_supervisor()) + return; + + max_bit = __fls(xfeatures_mask_supervisor()); + min_bit = __ffs(xfeatures_mask_supervisor()); + + lmask = xfeatures_mask_supervisor(); + hmask = xfeatures_mask_supervisor() >> 32; + XSTATE_OP(XSAVES, xstate, lmask, hmask, err); + + /* We should never fault when copying to a kernel buffer: */ + if (WARN_ON_FPU(err)) + return; + + /* + * At this point, the buffer has only supervisor states and must be + * converted back to normal kernel format. + */ + header = &xstate->header; + header->xcomp_bv |= xfeatures_mask_all; + + /* + * This only moves states up in the buffer. Start with + * the last state and move backwards so that states are + * not overwritten until after they are moved. Note: + * memmove() allows overlapping src/dst buffers. + */ + for (i = max_bit; i >= min_bit; i--) { + u8 *xbuf = (u8 *)xstate; + + if (!((header->xfeatures >> i) & 1)) + continue; + + /* Move xfeature 'i' into its normal location */ + memmove(xbuf + xstate_comp_offsets[i], + xbuf + xstate_supervisor_only_offsets[i], + xstate_sizes[i]); + } +} + #ifdef CONFIG_PROC_PID_ARCH_STATUS /* * Report the amount of time elapsed in millisecond since last AVX512 |