Add test that simulates early vector debug: attach to the process right after enabling vector context and check csr_vlenb.
Signed-off-by: Sergey Matyukevich geomatsi@gmail.com --- .../testing/selftests/riscv/vector/.gitignore | 1 + tools/testing/selftests/riscv/vector/Makefile | 5 +- .../testing/selftests/riscv/vector/v_ptrace.c | 84 +++++++++++++++++++ 3 files changed, 89 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/riscv/vector/v_ptrace.c
diff --git a/tools/testing/selftests/riscv/vector/.gitignore b/tools/testing/selftests/riscv/vector/.gitignore index 7d9c87cd0649..d21c03c3ee0e 100644 --- a/tools/testing/selftests/riscv/vector/.gitignore +++ b/tools/testing/selftests/riscv/vector/.gitignore @@ -2,3 +2,4 @@ vstate_exec_nolibc vstate_prctl v_initval v_exec_initval_nolibc +v_ptrace diff --git a/tools/testing/selftests/riscv/vector/Makefile b/tools/testing/selftests/riscv/vector/Makefile index 6f7497f4e7b3..c14ad127e7fb 100644 --- a/tools/testing/selftests/riscv/vector/Makefile +++ b/tools/testing/selftests/riscv/vector/Makefile @@ -2,7 +2,7 @@ # Copyright (C) 2021 ARM Limited # Originally tools/testing/arm64/abi/Makefile
-TEST_GEN_PROGS := v_initval vstate_prctl +TEST_GEN_PROGS := v_initval vstate_prctl v_ptrace TEST_GEN_PROGS_EXTENDED := vstate_exec_nolibc v_exec_initval_nolibc
include ../../lib.mk @@ -26,3 +26,6 @@ $(OUTPUT)/v_initval: v_initval.c $(OUTPUT)/sys_hwprobe.o $(OUTPUT)/v_helpers.o $(OUTPUT)/v_exec_initval_nolibc: v_exec_initval_nolibc.c $(CC) -nostdlib -static -include ../../../../include/nolibc/nolibc.h \ -Wall $(CFLAGS) $(LDFLAGS) $^ -o $@ -lgcc + +$(OUTPUT)/v_ptrace: v_ptrace.c $(OUTPUT)/sys_hwprobe.o $(OUTPUT)/v_helpers.o + $(CC) -static -o$@ $(CFLAGS) $(LDFLAGS) $^ diff --git a/tools/testing/selftests/riscv/vector/v_ptrace.c b/tools/testing/selftests/riscv/vector/v_ptrace.c new file mode 100644 index 000000000000..1ae1b6d44363 --- /dev/null +++ b/tools/testing/selftests/riscv/vector/v_ptrace.c @@ -0,0 +1,84 @@ +// SPDX-License-Identifier: GPL-2.0-only +#include <sys/ptrace.h> +#include <sys/types.h> +#include <sys/wait.h> +#include <sys/wait.h> +#include <sys/uio.h> +#include <unistd.h> +#include <errno.h> + +#include <linux/ptrace.h> +#include <linux/elf.h> + +#include "../../kselftest_harness.h" +#include "v_helpers.h" + +volatile unsigned long data = 0; +volatile unsigned long lock = 0; + +TEST(ptrace_vlenb) +{ + pid_t pid; + + if (!is_vector_supported() && !is_xtheadvector_supported()) + SKIP(return, "Vector not supported"); + + pid = fork(); + + ASSERT_LE(0, pid) { + TH_LOG("fork: %m"); + } + + if (pid == 0) { + while (lock == 0) + asm volatile("" : : "g"(lock) : "memory"); + + asm volatile("csrr %[data], vlenb" : [data] "=r"(data)); + asm volatile ("ebreak" : : : ); + } else { + struct __riscv_v_regset_state *regset_data; + size_t regset_size; + struct iovec iov; + unsigned long vlenb_csr; + int status; + + /* attach */ + + ASSERT_EQ(0, ptrace(PTRACE_ATTACH, pid, NULL, NULL)); + ASSERT_EQ(pid, waitpid(pid, &status, 0)); + ASSERT_TRUE(WIFSTOPPED(status)); + + /* unlock */ + + ASSERT_EQ(0, ptrace(PTRACE_POKEDATA, pid, &lock, 1)); + + /* resume and wait ebreak */ + + ASSERT_EQ(0, ptrace(PTRACE_CONT, pid, NULL, NULL)); + ASSERT_EQ(pid, waitpid(pid, &status, 0)); + ASSERT_TRUE(WIFSTOPPED(status)); + + /* read tracee vlenb via ptrace peek */ + + errno = 0; + vlenb_csr = ptrace(PTRACE_PEEKDATA, pid, &data, NULL); + ASSERT_FALSE((errno != 0) && (vlenb_csr == -1)); + + /* read tracee vlenb via ptrace regs */ + + regset_size = sizeof(struct __riscv_v_regset_state) + + vlenb_csr * 8 * 32; + regset_data = calloc(1, regset_size); + + iov.iov_base = regset_data; + iov.iov_len = regset_size; + + ASSERT_EQ(0, ptrace(PTRACE_GETREGSET, pid, NT_RISCV_VECTOR, &iov)); + + /* compare */ + + EXPECT_EQ(vlenb_csr, regset_data->vlenb); + } +} + +TEST_HARNESS_MAIN
Currently, vlenb in vstate is set to zero on vector context allocation and remains zero until the first context switch. This can expose an inconsistent vlenb value to user-space in early vector debug scenarios, e.g. when ptrace attaches to a tracee after the first vector instruction but before the first context switch. Fix this by setting the correct vlenb value during vector context allocation. Simple reproducer has been added to selftests: - tools/testing/selftests/riscv/vector/v_ptrace.c
Signed-off-by: Sergey Matyukevich geomatsi@gmail.com --- arch/riscv/kernel/vector.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/arch/riscv/kernel/vector.c b/arch/riscv/kernel/vector.c index 184f780c932d..6ba68568735b 100644 --- a/arch/riscv/kernel/vector.c +++ b/arch/riscv/kernel/vector.c @@ -120,6 +120,8 @@ static int riscv_v_thread_zalloc(struct kmem_cache *cache,
ctx->datap = datap; memset(ctx, 0, offsetof(struct __riscv_v_ext_state, datap)); + ctx->vlenb = riscv_v_vsize / 32; + return 0; }
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