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Bae" Cc: linux-kernel@vger.kernel.org, criu@lists.linux.dev, Thomas Gleixner , Ingo Molnar , Dave Hansen , x86@kernel.org, Andrei Vagin , Alexander Mikhalitsyn , "H. Peter Anvin" Content-Type: text/plain; charset="UTF-8" Extend sigframe_fpu_portability.c with two test cases for signal frames whose xstate_size exceeds the current task's fpstate->user_size: - test_valid_larger_xstate_size(): Verifies that the kernel restores FPU state from a signal frame with a larger xstate_size and an unsupported feature bit in _fpx_sw_bytes.xfeatures when the XSAVE header (XSTATE_BV) only contains supported features. This emulates migrating a process from a newer CPU to an older CPU when the process has not used any unsupported features. - test_invalid_larger_xstate_size(): Verifies that the kernel rejects (via SIGSEGV) a signal frame with a larger xstate_size when the XSAVE header (XSTATE_BV) marks an unsupported feature as active. Signed-off-by: Andrei Vagin --- .../selftests/x86/sigframe_fpu_portability.c | 118 ++++++++++++++++-- 1 file changed, 110 insertions(+), 8 deletions(-) diff --git a/tools/testing/selftests/x86/sigframe_fpu_portability.c b/tools/testing/selftests/x86/sigframe_fpu_portability.c index 8377de052032..afa9e6eab9b9 100644 --- a/tools/testing/selftests/x86/sigframe_fpu_portability.c +++ b/tools/testing/selftests/x86/sigframe_fpu_portability.c @@ -30,6 +30,14 @@ * - test_invalid_shrunk_xstate_size: * Verifies that the kernel rejects a frame if xstate_size is too small for * the features enabled in xfeatures. + * + * - test_valid_larger_xstate_size: + * Verifies that the kernel restores state from a frame with xstate_size + * larger than the current task's size, if no unsupported features are active. + * + * - test_invalid_larger_xstate_size: + * Verifies that the kernel rejects a frame with a larger xstate_size if it + * contains unsupported features in the xsave header. */ #define SIGFRAME_XSTATE_HDR_OFFSET 512 @@ -160,12 +168,13 @@ static void handle_invalid_shrunk_xstate_size(int sig, siginfo_t *si, void *ucp) __handle_shrunk_xstate_size(sig, si, ucp, false); } -static void test_valid_shrunk_xstate_size(void) +static void run_valid_sigframe_test(void (*handler)(int, siginfo_t *, void *), + const char *desc) { uint64_t v[4]; sig_err_buf[0] = 0; - sethandler(SIGUSR1, handle_valid_shrunk_xstate_size, 0); + sethandler(SIGUSR1, handler, 0); v[0] = 0x1111111111111111ULL; v[1] = 0x2222222222222222ULL; @@ -176,7 +185,7 @@ static void test_valid_shrunk_xstate_size(void) if (sig_err_buf[0]) ksft_test_result_fail("%s\n", sig_err_buf); else if (v[2] == TEST_YMMH_VAL && v[3] == (TEST_YMMH_VAL + 1)) - ksft_test_result_pass("YMM state restored correctly from shrunk frame\n"); + ksft_test_result_pass("%s\n", desc); else ksft_test_result_fail( "Got upper bits: 0x%lx 0x%lx (expected %lx %lx)\n", @@ -192,12 +201,13 @@ static void handle_segv(int sig, siginfo_t *si, void *ucp) siglongjmp(segv_jmpbuf, 1); } -static void test_invalid_shrunk_xstate_size(void) +static void run_invalid_sigframe_test(void (*handler)(int, siginfo_t *, void *), + const char *desc) { uint64_t v[4]; sig_err_buf[0] = 0; - sethandler(SIGUSR1, handle_invalid_shrunk_xstate_size, 0); + sethandler(SIGUSR1, handler, 0); sethandler(SIGSEGV, handle_segv, 0); if (sigsetjmp(segv_jmpbuf, 1) == 0) { @@ -206,7 +216,7 @@ static void test_invalid_shrunk_xstate_size(void) v[2] = 0x3333333333333333ULL; v[3] = 0x4444444444444444ULL; raise_with_ymm0(SIGUSR1, v); - sig_print("Inconsistent size was NOT rejected\n"); + sig_print("Invalid frame was NOT rejected\n"); } clearhandler(SIGUSR1); @@ -215,13 +225,103 @@ static void test_invalid_shrunk_xstate_size(void) if (sig_err_buf[0]) ksft_test_result_fail("%s\n", sig_err_buf); else - ksft_test_result_pass("Inconsistent size correctly rejected\n"); + ksft_test_result_pass("%s\n", desc); +} + +static void test_valid_shrunk_xstate_size(void) +{ + run_valid_sigframe_test(handle_valid_shrunk_xstate_size, + "YMM state restored correctly from shrunk frame"); +} + +static void test_invalid_shrunk_xstate_size(void) +{ + run_invalid_sigframe_test(handle_invalid_shrunk_xstate_size, + "Inconsistent shrunk xstate_size correctly rejected"); +} + +static char fpu_buffer[8192] __attribute__((aligned(64))); +#define UNSUPPORTED_XFEATURE (1ULL << 62) + +static void __handle_larger_xstate_size(int sig, siginfo_t *si, void *ucp, bool valid_xfeatures) +{ + uint64_t *ymmh_p, xfeatures; + struct xsave_buffer *xbuf; + struct _fpx_sw_bytes *sw; + ucontext_t *uc = ucp; + size_t copy_size; + void *fp; + + fp = uc->uc_mcontext.fpregs; + if (!fp) { + sig_print("fpregs is NULL\n"); + return; + } + + sw = get_fpx_sw_bytes(fp); + if (sw->magic1 != FP_XSTATE_MAGIC1) { + sig_print("magic1 is not valid\n"); + return; + } + + copy_size = sw->xstate_size; + if (copy_size + 64 + FP_XSTATE_MAGIC2_SIZE > sizeof(fpu_buffer)) { + sig_print("fpu_buffer is too small\n"); + return; + } + + memset(fpu_buffer, 0, sizeof(fpu_buffer)); + memcpy(fpu_buffer, fp, copy_size); + + xbuf = (struct xsave_buffer *)fpu_buffer; + sw = get_fpx_sw_bytes(fpu_buffer); + + sw->xstate_size += 64; + sw->extended_size += 64; + xfeatures = get_fpx_sw_bytes_features(fpu_buffer); + set_fpx_sw_bytes_features(fpu_buffer, xfeatures | UNSUPPORTED_XFEATURE); + + *(uint32_t *)(fpu_buffer + sw->xstate_size) = FP_XSTATE_MAGIC2; + + if (!valid_xfeatures) { + xfeatures = get_xstatebv(xbuf); + set_xstatebv(xbuf, xfeatures | UNSUPPORTED_XFEATURE); + } + + ymmh_p = (uint64_t *)(fpu_buffer + ymm_offset); + ymmh_p[0] = TEST_YMMH_VAL; + ymmh_p[1] = TEST_YMMH_VAL + 1; + + /* Update fpregs to point to the new buffer */ + uc->uc_mcontext.fpregs = (fpregset_t)fpu_buffer; +} + +static void handle_valid_larger_xstate_size(int sig, siginfo_t *si, void *ucp) +{ + __handle_larger_xstate_size(sig, si, ucp, true); +} + +static void handle_invalid_larger_xstate_size(int sig, siginfo_t *si, void *ucp) +{ + __handle_larger_xstate_size(sig, si, ucp, false); +} + +static void test_valid_larger_xstate_size(void) +{ + run_valid_sigframe_test(handle_valid_larger_xstate_size, + "YMM state restored correctly from larger frame"); +} + +static void test_invalid_larger_xstate_size(void) +{ + run_invalid_sigframe_test(handle_invalid_larger_xstate_size, + "Unsupported feature in larger frame correctly rejected"); } int main(void) { ksft_print_header(); - ksft_set_plan(2); + ksft_set_plan(4); self_pid = getpid(); @@ -229,6 +329,8 @@ int main(void) test_valid_shrunk_xstate_size(); test_invalid_shrunk_xstate_size(); + test_valid_larger_xstate_size(); + test_invalid_larger_xstate_size(); ksft_finished(); return 0; -- 2.56.0.rc1.315.gc6ed9934b7-goog