Messages in this thread Patch in this message |  | | From | "Chang S. Bae" <> | Subject | [PATCH v5 18/28] x86/fpu/xstate: Disable xstate support if an inconsistent state is detected | Date | Sun, 23 May 2021 12:32:49 -0700 |
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The kernel has a sanity check between two methods to calculate xstate size. In the unlikely event that they disagree, disable the use of xstate.
Suggested-by: Thomas Gleixner <tglx@linutronix.de> 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 v4: * Added as a new patch. (Thomas Gleixner) --- arch/x86/kernel/fpu/xstate.c | 33 ++++++++++++++++++++++----------- 1 file changed, 22 insertions(+), 11 deletions(-)
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index 1cf5888210aa..544e35a9d777 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -730,11 +730,11 @@ static void __xstate_dump_leaves(void) } while (0) #define XCHECK_SZ(sz, nr, nr_macro, __struct) do { \ - if ((nr == nr_macro) && \ - WARN_ONCE(sz != sizeof(__struct), \ - "%s: struct is %zu bytes, cpu state %d bytes\n", \ - __stringify(nr_macro), sizeof(__struct), sz)) { \ + if ((nr == nr_macro) && (sz != sizeof(__struct))) { \ + pr_err("%s: struct is %zu bytes, cpu state %d bytes\n", \ + __stringify(nr_macro), sizeof(__struct), sz); \ __xstate_dump_leaves(); \ + return -EINVAL; \ } \ } while (0) @@ -743,7 +743,7 @@ static void __xstate_dump_leaves(void) * that our software representation matches what the CPU * tells us about the state's size. */ -static void check_xstate_against_struct(int nr) +static int check_xstate_against_struct(int nr) { /* * Ask the CPU for the size of the state. @@ -771,9 +771,12 @@ static void check_xstate_against_struct(int nr) (nr >= XFEATURE_MAX) || (nr == XFEATURE_PT_UNIMPLEMENTED_SO_FAR) || ((nr >= XFEATURE_RSRVD_COMP_11) && (nr <= XFEATURE_LBR))) { - WARN_ONCE(1, "no structure for xstate: %d\n", nr); + pr_err("no structure for xstate: %d\n", nr); XSTATE_WARN_ON(1); + return -EINVAL; } + + return 0; } /** @@ -786,9 +789,9 @@ static void check_xstate_against_struct(int nr) * * Dynamic supervisor XSAVE features allocate their own buffers and are not covered by these checks. * - * Return: nothing. + * Returns 0 on success, -EINVAL on state size mismatch. */ -static void calculate_xstate_sizes(void) +static int calculate_xstate_sizes(void) { int paranoid_min_size = FXSAVE_SIZE + XSAVE_HDR_SIZE; int paranoid_max_size = FXSAVE_SIZE + XSAVE_HDR_SIZE; @@ -796,13 +799,17 @@ static void calculate_xstate_sizes(void) for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) { bool user_dynamic; + int err; if (!xfeature_enabled(i)) continue; user_dynamic = (xfeatures_mask_user_dynamic & BIT_ULL(i)) ? true : false; - check_xstate_against_struct(i); + err = check_xstate_against_struct(i); + if (err) + return err; + /* * Supervisor state components can be managed only by * XSAVES, which is compacted-format only. @@ -837,6 +844,7 @@ static void calculate_xstate_sizes(void) } XSTATE_WARN_ON(paranoid_max_size != get_xstate_config(XSTATE_MAX_SIZE)); set_xstate_config(XSTATE_MIN_SIZE, paranoid_min_size); + return 0; } @@ -923,6 +931,7 @@ static int __init init_xstate_size(void) /* Recompute the context size for enabled features: */ unsigned int possible_xstate_size; unsigned int xsave_size; + int err; xsave_size = get_xsave_size(); @@ -939,9 +948,11 @@ static int __init init_xstate_size(void) /* * Calculate and double-check the maximum size. Calculate and record - * the minimum size. + * the minimum size. Emit the error when received. */ - calculate_xstate_sizes(); + err = calculate_xstate_sizes(); + if (err) + return err; /* Ensure the minimum size fits in the statically-alocated buffer: */ if (!is_supported_xstate_size(get_xstate_config(XSTATE_MIN_SIZE))) -- 2.17.1
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