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Shutemov" Subject: Re: [PATCH v4 07/10] selftests: riscv: Add a pointer masking test Message-ID: References: <20240829010151.2813377-1-samuel.holland@sifive.com> <20240829010151.2813377-8-samuel.holland@sifive.com> Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240829010151.2813377-8-samuel.holland@sifive.com> On Wed, Aug 28, 2024 at 06:01:29PM -0700, Samuel Holland wrote: > This test covers the behavior of the PR_SET_TAGGED_ADDR_CTRL and > PR_GET_TAGGED_ADDR_CTRL prctl() operations, their effects on the > userspace ABI, and their effects on the system call ABI. > > Signed-off-by: Samuel Holland Reviewed-by: Charlie Jenkins Tested-by: Charlie Jenkins > --- > > (no changes since v2) > > Changes in v2: > - Rename "tags" directory to "pm" to avoid .gitignore rules > - Add .gitignore file to ignore the compiled selftest binary > - Write to a pipe to force dereferencing the user pointer > - Handle SIGSEGV in the child process to reduce dmesg noise > > tools/testing/selftests/riscv/Makefile | 2 +- > tools/testing/selftests/riscv/pm/.gitignore | 1 + > tools/testing/selftests/riscv/pm/Makefile | 10 + > .../selftests/riscv/pm/pointer_masking.c | 330 ++++++++++++++++++ > 4 files changed, 342 insertions(+), 1 deletion(-) > create mode 100644 tools/testing/selftests/riscv/pm/.gitignore > create mode 100644 tools/testing/selftests/riscv/pm/Makefile > create mode 100644 tools/testing/selftests/riscv/pm/pointer_masking.c > > diff --git a/tools/testing/selftests/riscv/Makefile b/tools/testing/selftests/riscv/Makefile > index 7ce03d832b64..2ee1d1548c5f 100644 > --- a/tools/testing/selftests/riscv/Makefile > +++ b/tools/testing/selftests/riscv/Makefile > @@ -5,7 +5,7 @@ > ARCH ?= $(shell uname -m 2>/dev/null || echo not) > > ifneq (,$(filter $(ARCH),riscv)) > -RISCV_SUBTARGETS ?= hwprobe vector mm sigreturn > +RISCV_SUBTARGETS ?= hwprobe mm pm sigreturn vector > else > RISCV_SUBTARGETS := > endif > diff --git a/tools/testing/selftests/riscv/pm/.gitignore b/tools/testing/selftests/riscv/pm/.gitignore > new file mode 100644 > index 000000000000..b38358f91c4d > --- /dev/null > +++ b/tools/testing/selftests/riscv/pm/.gitignore > @@ -0,0 +1 @@ > +pointer_masking > diff --git a/tools/testing/selftests/riscv/pm/Makefile b/tools/testing/selftests/riscv/pm/Makefile > new file mode 100644 > index 000000000000..ed82ff9c664e > --- /dev/null > +++ b/tools/testing/selftests/riscv/pm/Makefile > @@ -0,0 +1,10 @@ > +# SPDX-License-Identifier: GPL-2.0 > + > +CFLAGS += -I$(top_srcdir)/tools/include > + > +TEST_GEN_PROGS := pointer_masking > + > +include ../../lib.mk > + > +$(OUTPUT)/pointer_masking: pointer_masking.c > + $(CC) -static -o$@ $(CFLAGS) $(LDFLAGS) $^ > diff --git a/tools/testing/selftests/riscv/pm/pointer_masking.c b/tools/testing/selftests/riscv/pm/pointer_masking.c > new file mode 100644 > index 000000000000..0fe80f963ace > --- /dev/null > +++ b/tools/testing/selftests/riscv/pm/pointer_masking.c > @@ -0,0 +1,330 @@ > +// SPDX-License-Identifier: GPL-2.0-only > + > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > + > +#include "../../kselftest.h" > + > +#ifndef PR_PMLEN_SHIFT > +#define PR_PMLEN_SHIFT 24 > +#endif > +#ifndef PR_PMLEN_MASK > +#define PR_PMLEN_MASK (0x7fUL << PR_PMLEN_SHIFT) > +#endif > + > +static int dev_zero; > + > +static int pipefd[2]; > + > +static sigjmp_buf jmpbuf; > + > +static void sigsegv_handler(int sig) > +{ > + siglongjmp(jmpbuf, 1); > +} > + > +static int min_pmlen; > +static int max_pmlen; > + > +static inline bool valid_pmlen(int pmlen) > +{ > + return pmlen == 0 || pmlen == 7 || pmlen == 16; > +} > + > +static void test_pmlen(void) > +{ > + ksft_print_msg("Testing available PMLEN values\n"); > + > + for (int request = 0; request <= 16; request++) { > + int pmlen, ret; > + > + ret = prctl(PR_SET_TAGGED_ADDR_CTRL, request << PR_PMLEN_SHIFT, 0, 0, 0); > + if (ret) > + goto pr_set_error; > + > + ret = prctl(PR_GET_TAGGED_ADDR_CTRL, 0, 0, 0, 0); > + ksft_test_result(ret >= 0, "PMLEN=%d PR_GET_TAGGED_ADDR_CTRL\n", request); > + if (ret < 0) > + goto pr_get_error; > + > + pmlen = (ret & PR_PMLEN_MASK) >> PR_PMLEN_SHIFT; > + ksft_test_result(pmlen >= request, "PMLEN=%d constraint\n", request); > + ksft_test_result(valid_pmlen(pmlen), "PMLEN=%d validity\n", request); > + > + if (min_pmlen == 0) > + min_pmlen = pmlen; > + if (max_pmlen < pmlen) > + max_pmlen = pmlen; > + > + continue; > + > +pr_set_error: > + ksft_test_result_skip("PMLEN=%d PR_GET_TAGGED_ADDR_CTRL\n", request); > +pr_get_error: > + ksft_test_result_skip("PMLEN=%d constraint\n", request); > + ksft_test_result_skip("PMLEN=%d validity\n", request); > + } > + > + if (max_pmlen == 0) > + ksft_exit_fail_msg("Failed to enable pointer masking\n"); > +} > + > +static int set_tagged_addr_ctrl(int pmlen, bool tagged_addr_abi) > +{ > + int arg, ret; > + > + arg = pmlen << PR_PMLEN_SHIFT | tagged_addr_abi; > + ret = prctl(PR_SET_TAGGED_ADDR_CTRL, arg, 0, 0, 0); > + if (!ret) { > + ret = prctl(PR_GET_TAGGED_ADDR_CTRL, 0, 0, 0, 0); > + if (ret == arg) > + return 0; > + } > + > + return ret < 0 ? -errno : -ENODATA; > +} > + > +static void test_dereference_pmlen(int pmlen) > +{ > + static volatile int i; > + volatile int *p; > + int ret; > + > + ret = set_tagged_addr_ctrl(pmlen, false); > + if (ret) > + return ksft_test_result_error("PMLEN=%d setup (%d)\n", pmlen, ret); > + > + i = pmlen; > + > + if (pmlen) { > + p = (volatile int *)((uintptr_t)&i | 1UL << __riscv_xlen - pmlen); > + > + /* These dereferences should succeed. */ > + if (sigsetjmp(jmpbuf, 1)) > + return ksft_test_result_fail("PMLEN=%d valid tag\n", pmlen); > + if (*p != pmlen) > + return ksft_test_result_fail("PMLEN=%d bad value\n", pmlen); > + *p++; > + } > + > + p = (volatile int *)((uintptr_t)&i | 1UL << __riscv_xlen - pmlen - 1); > + > + /* These dereferences should raise SIGSEGV. */ > + if (sigsetjmp(jmpbuf, 1)) > + return ksft_test_result_pass("PMLEN=%d dereference\n", pmlen); > + *p++; > + ksft_test_result_fail("PMLEN=%d invalid tag\n", pmlen); > +} > + > +static void test_dereference(void) > +{ > + ksft_print_msg("Testing userspace pointer dereference\n"); > + > + signal(SIGSEGV, sigsegv_handler); > + > + test_dereference_pmlen(0); > + test_dereference_pmlen(min_pmlen); > + test_dereference_pmlen(max_pmlen); > + > + signal(SIGSEGV, SIG_DFL); > +} > + > +static void execve_child_sigsegv_handler(int sig) > +{ > + exit(42); > +} > + > +static int execve_child(void) > +{ > + static volatile int i; > + volatile int *p = (volatile int *)((uintptr_t)&i | 1UL << __riscv_xlen - 7); > + > + signal(SIGSEGV, execve_child_sigsegv_handler); > + > + /* This dereference should raise SIGSEGV. */ > + return *p; > +} > + > +static void test_fork_exec(void) > +{ > + int ret, status; > + > + ksft_print_msg("Testing fork/exec behavior\n"); > + > + ret = set_tagged_addr_ctrl(min_pmlen, false); > + if (ret) > + return ksft_test_result_error("setup (%d)\n", ret); > + > + if (fork()) { > + wait(&status); > + ksft_test_result(WIFEXITED(status) && WEXITSTATUS(status) == 42, > + "dereference after fork\n"); > + } else { > + static volatile int i = 42; > + volatile int *p = (volatile int *)((uintptr_t)&i | 1UL << __riscv_xlen - min_pmlen); > + > + /* This dereference should succeed. */ > + exit(*p); > + } > + > + if (fork()) { > + wait(&status); > + ksft_test_result(WIFEXITED(status) && WEXITSTATUS(status) == 42, > + "dereference after fork+exec\n"); > + } else { > + /* Will call execve_child(). */ > + execve("/proc/self/exe", (char *const []) { "", NULL }, NULL); > + } > +} > + > +static void test_tagged_addr_abi_sysctl(void) > +{ > + char value; > + int fd; > + > + ksft_print_msg("Testing tagged address ABI sysctl\n"); > + > + fd = open("/proc/sys/abi/tagged_addr_disabled", O_WRONLY); > + if (fd < 0) { > + ksft_test_result_skip("failed to open sysctl file\n"); > + ksft_test_result_skip("failed to open sysctl file\n"); > + return; > + } > + > + value = '1'; > + pwrite(fd, &value, 1, 0); > + ksft_test_result(set_tagged_addr_ctrl(min_pmlen, true) == -EINVAL, > + "sysctl disabled\n"); > + > + value = '0'; > + pwrite(fd, &value, 1, 0); > + ksft_test_result(set_tagged_addr_ctrl(min_pmlen, true) == 0, > + "sysctl enabled\n"); > + > + set_tagged_addr_ctrl(0, false); > + > + close(fd); > +} > + > +static void test_tagged_addr_abi_pmlen(int pmlen) > +{ > + int i, *p, ret; > + > + i = ~pmlen; > + > + if (pmlen) { > + p = (int *)((uintptr_t)&i | 1UL << __riscv_xlen - pmlen); I am trying to put something together with https://lore.kernel.org/linux-mm/20240905-patches-below_hint_mmap-v3-2-3cd5564efbbb@rivosinc.com/T/ to ensure that the upper addresses aren't allocated. This is only relevant on sv57 and PMLEN=16 hardware where addresses could overlap. > + > + ret = set_tagged_addr_ctrl(pmlen, false); > + if (ret) > + return ksft_test_result_error("PMLEN=%d ABI disabled setup (%d)\n", > + pmlen, ret); > + > + ret = write(pipefd[1], p, sizeof(*p)); > + if (ret >= 0 || errno != EFAULT) > + return ksft_test_result_fail("PMLEN=%d ABI disabled write\n", pmlen); > + > + ret = read(dev_zero, p, sizeof(*p)); > + if (ret >= 0 || errno != EFAULT) > + return ksft_test_result_fail("PMLEN=%d ABI disabled read\n", pmlen); > + > + if (i != ~pmlen) > + return ksft_test_result_fail("PMLEN=%d ABI disabled value\n", pmlen); > + > + ret = set_tagged_addr_ctrl(pmlen, true); > + if (ret) > + return ksft_test_result_error("PMLEN=%d ABI enabled setup (%d)\n", > + pmlen, ret); > + > + ret = write(pipefd[1], p, sizeof(*p)); > + if (ret != sizeof(*p)) > + return ksft_test_result_fail("PMLEN=%d ABI enabled write\n", pmlen); > + > + ret = read(dev_zero, p, sizeof(*p)); > + if (ret != sizeof(*p)) > + return ksft_test_result_fail("PMLEN=%d ABI enabled read\n", pmlen); > + > + if (i) > + return ksft_test_result_fail("PMLEN=%d ABI enabled value\n", pmlen); > + > + i = ~pmlen; > + } else { > + /* The tagged address ABI cannot be enabled when PMLEN == 0. */ > + ret = set_tagged_addr_ctrl(pmlen, true); > + if (ret != -EINVAL) > + return ksft_test_result_error("PMLEN=%d ABI setup (%d)\n", > + pmlen, ret); > + } > + > + p = (int *)((uintptr_t)&i | 1UL << __riscv_xlen - pmlen - 1); > + > + ret = write(pipefd[1], p, sizeof(*p)); > + if (ret >= 0 || errno != EFAULT) > + return ksft_test_result_fail("PMLEN=%d invalid tag write (%d)\n", pmlen, errno); > + > + ret = read(dev_zero, p, sizeof(*p)); > + if (ret >= 0 || errno != EFAULT) > + return ksft_test_result_fail("PMLEN=%d invalid tag read\n", pmlen); > + > + if (i != ~pmlen) > + return ksft_test_result_fail("PMLEN=%d invalid tag value\n", pmlen); > + > + ksft_test_result_pass("PMLEN=%d tagged address ABI\n", pmlen); > +} > + > +static void test_tagged_addr_abi(void) > +{ > + ksft_print_msg("Testing tagged address ABI\n"); > + > + test_tagged_addr_abi_pmlen(0); > + test_tagged_addr_abi_pmlen(min_pmlen); > + test_tagged_addr_abi_pmlen(max_pmlen); > +} > + > +static struct test_info { > + unsigned int nr_tests; > + void (*test_fn)(void); > +} tests[] = { > + { .nr_tests = 17 * 3, test_pmlen }, > + { .nr_tests = 3, test_dereference }, > + { .nr_tests = 2, test_fork_exec }, > + { .nr_tests = 2, test_tagged_addr_abi_sysctl }, > + { .nr_tests = 3, test_tagged_addr_abi }, > +}; > + > +int main(int argc, char **argv) > +{ > + unsigned int plan = 0; > + int ret; > + > + /* Check if this is the child process after execve(). */ > + if (!argv[0][0]) > + return execve_child(); > + > + dev_zero = open("/dev/zero", O_RDWR); > + if (dev_zero < 0) > + return 1; > + > + /* Write to a pipe so the kernel must dereference the buffer pointer. */ > + ret = pipe(pipefd); > + if (ret) > + return 1; > + > + ksft_print_header(); > + > + for (int i = 0; i < ARRAY_SIZE(tests); ++i) > + plan += tests[i].nr_tests; > + > + ksft_set_plan(plan); > + > + for (int i = 0; i < ARRAY_SIZE(tests); ++i) > + tests[i].test_fn(); > + > + ksft_finished(); > +} > -- > 2.45.1 > > > _______________________________________________ > linux-riscv mailing list > linux-riscv@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-riscv