diff options
Diffstat (limited to 'tools/testing/selftests/rseq/rseq.c')
| -rw-r--r-- | tools/testing/selftests/rseq/rseq.c | 72 |
1 files changed, 40 insertions, 32 deletions
diff --git a/tools/testing/selftests/rseq/rseq.c b/tools/testing/selftests/rseq/rseq.c index f6156790c3b4..be0d0a97031e 100644 --- a/tools/testing/selftests/rseq/rseq.c +++ b/tools/testing/selftests/rseq/rseq.c @@ -33,16 +33,16 @@ #include <linux/compiler.h> -#include "../kselftest.h" +#include "kselftest.h" #include "rseq.h" /* * Define weak versions to play nice with binaries that are statically linked * against a libc that doesn't support registering its own rseq. */ -__weak ptrdiff_t __rseq_offset; -__weak unsigned int __rseq_size; -__weak unsigned int __rseq_flags; +extern __weak ptrdiff_t __rseq_offset; +extern __weak unsigned int __rseq_size; +extern __weak unsigned int __rseq_flags; static const ptrdiff_t *libc_rseq_offset_p = &__rseq_offset; static const unsigned int *libc_rseq_size_p = &__rseq_size; @@ -56,6 +56,7 @@ ptrdiff_t rseq_offset; * unsuccessful. */ unsigned int rseq_size = -1U; +static unsigned int rseq_alloc_size; /* Flags used during rseq registration. */ unsigned int rseq_flags; @@ -71,9 +72,20 @@ static int rseq_ownership; /* Original struct rseq allocation size is 32 bytes. */ #define ORIG_RSEQ_ALLOC_SIZE 32 +/* + * Use a union to ensure we allocate a TLS area of 1024 bytes to accomodate an + * rseq registration that is larger than the current rseq ABI. + */ +union rseq_tls { + struct rseq_abi abi; + char dummy[RSEQ_THREAD_AREA_ALLOC_SIZE]; +}; + static -__thread struct rseq_abi __rseq_abi __attribute__((tls_model("initial-exec"), aligned(RSEQ_THREAD_AREA_ALLOC_SIZE))) = { - .cpu_id = RSEQ_ABI_CPU_ID_UNINITIALIZED, +__thread union rseq_tls __rseq __attribute__((tls_model("initial-exec"))) = { + .abi = { + .cpu_id = RSEQ_ABI_CPU_ID_UNINITIALIZED, + }, }; static int sys_rseq(struct rseq_abi *rseq_abi, uint32_t rseq_len, @@ -87,7 +99,7 @@ static int sys_getcpu(unsigned *cpu, unsigned *node) return syscall(__NR_getcpu, cpu, node, NULL); } -int rseq_available(void) +bool rseq_available(void) { int rc; @@ -96,37 +108,25 @@ int rseq_available(void) abort(); switch (errno) { case ENOSYS: - return 0; + return false; case EINVAL: - return 1; + return true; default: abort(); } } -/* The rseq areas need to be at least 32 bytes. */ -static -unsigned int get_rseq_min_alloc_size(void) -{ - unsigned int alloc_size = rseq_size; - - if (alloc_size < ORIG_RSEQ_ALLOC_SIZE) - alloc_size = ORIG_RSEQ_ALLOC_SIZE; - return alloc_size; -} - /* * Return the feature size supported by the kernel. * * Depending on the value returned by getauxval(AT_RSEQ_FEATURE_SIZE): * - * 0: Return ORIG_RSEQ_FEATURE_SIZE (20) + * 0: Return ORIG_RSEQ_FEATURE_SIZE (20) * > 0: Return the value from getauxval(AT_RSEQ_FEATURE_SIZE). * * It should never return a value below ORIG_RSEQ_FEATURE_SIZE. */ -static -unsigned int get_rseq_kernel_feature_size(void) +static unsigned int get_rseq_kernel_feature_size(void) { unsigned long auxv_rseq_feature_size, auxv_rseq_align; @@ -141,15 +141,24 @@ unsigned int get_rseq_kernel_feature_size(void) return ORIG_RSEQ_FEATURE_SIZE; } -int rseq_register_current_thread(void) +int __rseq_register_current_thread(bool nolibc, bool legacy) { + unsigned int size; int rc; if (!rseq_ownership) { /* Treat libc's ownership as a successful registration. */ - return 0; + return nolibc ? -EBUSY : 0; } - rc = sys_rseq(&__rseq_abi, get_rseq_min_alloc_size(), 0, RSEQ_SIG); + + /* The minimal allocation size is 32, which is the legacy allocation size */ + size = get_rseq_kernel_feature_size(); + if (legacy || size < ORIG_RSEQ_ALLOC_SIZE) + rseq_alloc_size = ORIG_RSEQ_ALLOC_SIZE; + else + rseq_alloc_size = size; + + rc = sys_rseq(&__rseq.abi, rseq_alloc_size, 0, RSEQ_SIG); if (rc) { /* * After at least one thread has registered successfully @@ -168,9 +177,8 @@ int rseq_register_current_thread(void) * The first thread to register sets the rseq_size to mimic the libc * behavior. */ - if (RSEQ_READ_ONCE(rseq_size) == 0) { - RSEQ_WRITE_ONCE(rseq_size, get_rseq_kernel_feature_size()); - } + if (RSEQ_READ_ONCE(rseq_size) == 0) + RSEQ_WRITE_ONCE(rseq_size, size); return 0; } @@ -183,7 +191,7 @@ int rseq_unregister_current_thread(void) /* Treat libc's ownership as a successful unregistration. */ return 0; } - rc = sys_rseq(&__rseq_abi, get_rseq_min_alloc_size(), RSEQ_ABI_FLAG_UNREGISTER, RSEQ_SIG); + rc = sys_rseq(&__rseq.abi, rseq_alloc_size, RSEQ_ABI_FLAG_UNREGISTER, RSEQ_SIG); if (rc) return -1; return 0; @@ -198,7 +206,7 @@ void rseq_init(void) * libc not having registered a restartable sequence. Try to find the * symbols if that's the case. */ - if (!*libc_rseq_size_p) { + if (!libc_rseq_size_p || !*libc_rseq_size_p) { libc_rseq_offset_p = dlsym(RTLD_NEXT, "__rseq_offset"); libc_rseq_size_p = dlsym(RTLD_NEXT, "__rseq_size"); libc_rseq_flags_p = dlsym(RTLD_NEXT, "__rseq_flags"); @@ -249,7 +257,7 @@ void rseq_init(void) rseq_ownership = 1; /* Calculate the offset of the rseq area from the thread pointer. */ - rseq_offset = (void *)&__rseq_abi - rseq_thread_pointer(); + rseq_offset = (void *)&__rseq.abi - rseq_thread_pointer(); /* rseq flags are deprecated, always set to 0. */ rseq_flags = 0; |