From d4846c33ebe04d2141dcc613b5558d2f1d8077af Mon Sep 17 00:00:00 2001 From: Ilya Leoshkevich Date: Fri, 23 Dec 2022 13:02:52 +0100 Subject: [PATCH] tests/tcg/multiarch: add vma-pthread.c MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Add a test that locklessly changes and exercises page protection bits from various threads. This helps catch race conditions in the VMA handling. Acked-by: Alex Bennée Signed-off-by: Ilya Leoshkevich Message-Id: <20221223120252.513319-1-iii@linux.ibm.com> Signed-off-by: Richard Henderson --- tests/tcg/multiarch/Makefile.target | 3 + tests/tcg/multiarch/munmap-pthread.c | 16 +-- tests/tcg/multiarch/nop_func.h | 25 ++++ tests/tcg/multiarch/vma-pthread.c | 207 +++++++++++++++++++++++++++ 4 files changed, 236 insertions(+), 15 deletions(-) create mode 100644 tests/tcg/multiarch/nop_func.h create mode 100644 tests/tcg/multiarch/vma-pthread.c diff --git a/tests/tcg/multiarch/Makefile.target b/tests/tcg/multiarch/Makefile.target index 5f0fee1aad..e7213af492 100644 --- a/tests/tcg/multiarch/Makefile.target +++ b/tests/tcg/multiarch/Makefile.target @@ -39,6 +39,9 @@ signals: LDFLAGS+=-lrt -lpthread munmap-pthread: CFLAGS+=-pthread munmap-pthread: LDFLAGS+=-pthread +vma-pthread: CFLAGS+=-pthread +vma-pthread: LDFLAGS+=-pthread + # We define the runner for test-mmap after the individual # architectures have defined their supported pages sizes. If no # additional page sizes are defined we only run the default test. diff --git a/tests/tcg/multiarch/munmap-pthread.c b/tests/tcg/multiarch/munmap-pthread.c index d7143b00d5..1c79005846 100644 --- a/tests/tcg/multiarch/munmap-pthread.c +++ b/tests/tcg/multiarch/munmap-pthread.c @@ -7,21 +7,7 @@ #include #include -static const char nop_func[] = { -#if defined(__aarch64__) - 0xc0, 0x03, 0x5f, 0xd6, /* ret */ -#elif defined(__alpha__) - 0x01, 0x80, 0xFA, 0x6B, /* ret */ -#elif defined(__arm__) - 0x1e, 0xff, 0x2f, 0xe1, /* bx lr */ -#elif defined(__riscv) - 0x67, 0x80, 0x00, 0x00, /* ret */ -#elif defined(__s390__) - 0x07, 0xfe, /* br %r14 */ -#elif defined(__i386__) || defined(__x86_64__) - 0xc3, /* ret */ -#endif -}; +#include "nop_func.h" static void *thread_mmap_munmap(void *arg) { diff --git a/tests/tcg/multiarch/nop_func.h b/tests/tcg/multiarch/nop_func.h new file mode 100644 index 0000000000..f714d21000 --- /dev/null +++ b/tests/tcg/multiarch/nop_func.h @@ -0,0 +1,25 @@ +/* + * No-op functions that can be safely copied. + * + * SPDX-License-Identifier: GPL-2.0-or-later + */ +#ifndef NOP_FUNC_H +#define NOP_FUNC_H + +static const char nop_func[] = { +#if defined(__aarch64__) + 0xc0, 0x03, 0x5f, 0xd6, /* ret */ +#elif defined(__alpha__) + 0x01, 0x80, 0xFA, 0x6B, /* ret */ +#elif defined(__arm__) + 0x1e, 0xff, 0x2f, 0xe1, /* bx lr */ +#elif defined(__riscv) + 0x67, 0x80, 0x00, 0x00, /* ret */ +#elif defined(__s390__) + 0x07, 0xfe, /* br %r14 */ +#elif defined(__i386__) || defined(__x86_64__) + 0xc3, /* ret */ +#endif +}; + +#endif diff --git a/tests/tcg/multiarch/vma-pthread.c b/tests/tcg/multiarch/vma-pthread.c new file mode 100644 index 0000000000..7045da08fc --- /dev/null +++ b/tests/tcg/multiarch/vma-pthread.c @@ -0,0 +1,207 @@ +/* + * Test that VMA updates do not race. + * + * SPDX-License-Identifier: GPL-2.0-or-later + * + * Map a contiguous chunk of RWX memory. Split it into 8 equally sized + * regions, each of which is guaranteed to have a certain combination of + * protection bits set. + * + * Reader, writer and executor threads perform the respective operations on + * pages, which are guaranteed to have the respective protection bit set. + * Two mutator threads change the non-fixed protection bits randomly. + */ +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "nop_func.h" + +#define PAGE_IDX_BITS 10 +#define PAGE_COUNT (1 << PAGE_IDX_BITS) +#define PAGE_IDX_MASK (PAGE_COUNT - 1) +#define REGION_IDX_BITS 3 +#define PAGE_IDX_R_MASK (1 << 7) +#define PAGE_IDX_W_MASK (1 << 8) +#define PAGE_IDX_X_MASK (1 << 9) +#define REGION_MASK (PAGE_IDX_R_MASK | PAGE_IDX_W_MASK | PAGE_IDX_X_MASK) +#define PAGES_PER_REGION (1 << (PAGE_IDX_BITS - REGION_IDX_BITS)) + +struct context { + int pagesize; + char *ptr; + int dev_null_fd; + volatile int mutator_count; +}; + +static void *thread_read(void *arg) +{ + struct context *ctx = arg; + ssize_t sret; + size_t i, j; + int ret; + + for (i = 0; ctx->mutator_count; i++) { + char *p; + + j = (i & PAGE_IDX_MASK) | PAGE_IDX_R_MASK; + p = &ctx->ptr[j * ctx->pagesize]; + + /* Read directly. */ + ret = memcmp(p, nop_func, sizeof(nop_func)); + if (ret != 0) { + fprintf(stderr, "fail direct read %p\n", p); + abort(); + } + + /* Read indirectly. */ + sret = write(ctx->dev_null_fd, p, 1); + if (sret != 1) { + if (sret < 0) { + fprintf(stderr, "fail indirect read %p (%m)\n", p); + } else { + fprintf(stderr, "fail indirect read %p (%zd)\n", p, sret); + } + abort(); + } + } + + return NULL; +} + +static void *thread_write(void *arg) +{ + struct context *ctx = arg; + struct timespec *ts; + size_t i, j; + int ret; + + for (i = 0; ctx->mutator_count; i++) { + j = (i & PAGE_IDX_MASK) | PAGE_IDX_W_MASK; + + /* Write directly. */ + memcpy(&ctx->ptr[j * ctx->pagesize], nop_func, sizeof(nop_func)); + + /* Write using a syscall. */ + ts = (struct timespec *)(&ctx->ptr[(j + 1) * ctx->pagesize] - + sizeof(struct timespec)); + ret = clock_gettime(CLOCK_REALTIME, ts); + if (ret != 0) { + fprintf(stderr, "fail indirect write %p (%m)\n", ts); + abort(); + } + } + + return NULL; +} + +static void *thread_execute(void *arg) +{ + struct context *ctx = arg; + size_t i, j; + + for (i = 0; ctx->mutator_count; i++) { + j = (i & PAGE_IDX_MASK) | PAGE_IDX_X_MASK; + ((void(*)(void))&ctx->ptr[j * ctx->pagesize])(); + } + + return NULL; +} + +static void *thread_mutate(void *arg) +{ + size_t i, start_idx, end_idx, page_idx, tmp; + struct context *ctx = arg; + unsigned int seed; + int prot, ret; + + seed = (unsigned int)time(NULL); + for (i = 0; i < 10000; i++) { + start_idx = rand_r(&seed) & PAGE_IDX_MASK; + end_idx = rand_r(&seed) & PAGE_IDX_MASK; + if (start_idx > end_idx) { + tmp = start_idx; + start_idx = end_idx; + end_idx = tmp; + } + prot = rand_r(&seed) & (PROT_READ | PROT_WRITE | PROT_EXEC); + for (page_idx = start_idx & REGION_MASK; page_idx <= end_idx; + page_idx += PAGES_PER_REGION) { + if (page_idx & PAGE_IDX_R_MASK) { + prot |= PROT_READ; + } + if (page_idx & PAGE_IDX_W_MASK) { + /* FIXME: qemu syscalls check for both read+write. */ + prot |= PROT_WRITE | PROT_READ; + } + if (page_idx & PAGE_IDX_X_MASK) { + prot |= PROT_EXEC; + } + } + ret = mprotect(&ctx->ptr[start_idx * ctx->pagesize], + (end_idx - start_idx + 1) * ctx->pagesize, prot); + assert(ret == 0); + } + + __atomic_fetch_sub(&ctx->mutator_count, 1, __ATOMIC_SEQ_CST); + + return NULL; +} + +int main(void) +{ + pthread_t threads[5]; + struct context ctx; + size_t i; + int ret; + + /* Without a template, nothing to test. */ + if (sizeof(nop_func) == 0) { + return EXIT_SUCCESS; + } + + /* Initialize memory chunk. */ + ctx.pagesize = getpagesize(); + ctx.ptr = mmap(NULL, PAGE_COUNT * ctx.pagesize, + PROT_READ | PROT_WRITE | PROT_EXEC, + MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); + assert(ctx.ptr != MAP_FAILED); + for (i = 0; i < PAGE_COUNT; i++) { + memcpy(&ctx.ptr[i * ctx.pagesize], nop_func, sizeof(nop_func)); + } + ctx.dev_null_fd = open("/dev/null", O_WRONLY); + assert(ctx.dev_null_fd >= 0); + ctx.mutator_count = 2; + + /* Start threads. */ + ret = pthread_create(&threads[0], NULL, thread_read, &ctx); + assert(ret == 0); + ret = pthread_create(&threads[1], NULL, thread_write, &ctx); + assert(ret == 0); + ret = pthread_create(&threads[2], NULL, thread_execute, &ctx); + assert(ret == 0); + for (i = 3; i <= 4; i++) { + ret = pthread_create(&threads[i], NULL, thread_mutate, &ctx); + assert(ret == 0); + } + + /* Wait for threads to stop. */ + for (i = 0; i < sizeof(threads) / sizeof(threads[0]); i++) { + ret = pthread_join(threads[i], NULL); + assert(ret == 0); + } + + /* Destroy memory chunk. */ + ret = close(ctx.dev_null_fd); + assert(ret == 0); + ret = munmap(ctx.ptr, PAGE_COUNT * ctx.pagesize); + assert(ret == 0); + + return EXIT_SUCCESS; +}