6.10-stable review patch. If anyone has any objections, please let me know.
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From: Puranjay Mohan puranjay@kernel.org
[ Upstream commit e1ef78dce9b7b0fa7f9d88bb3554441d74d33b34 ]
On ARM64 the stack pointer should be aligned at a 16 byte boundary or the SPAlignmentFault can occur. The fexit_sleep selftest allocates the stack for the child process as a character array, this is not guaranteed to be aligned at 16 bytes.
Because of the SPAlignmentFault, the child process is killed before it can do the nanosleep call and hence fentry_cnt remains as 0. This causes the main thread to hang on the following line:
while (READ_ONCE(fexit_skel->bss->fentry_cnt) != 2);
Fix this by allocating the stack using mmap() as described in the example in the man page of clone().
Remove the fexit_sleep test from the DENYLIST of arm64.
Fixes: eddbe8e65214 ("selftest/bpf: Add a test to check trampoline freeing logic.") Signed-off-by: Puranjay Mohan puranjay@kernel.org Signed-off-by: Daniel Borkmann daniel@iogearbox.net Link: https://lore.kernel.org/bpf/20240715173327.8657-1-puranjay@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- tools/testing/selftests/bpf/DENYLIST.aarch64 | 1 - tools/testing/selftests/bpf/prog_tests/fexit_sleep.c | 8 +++++++- 2 files changed, 7 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/bpf/DENYLIST.aarch64 b/tools/testing/selftests/bpf/DENYLIST.aarch64 index 0445ac38bc07d..3a2261248e9af 100644 --- a/tools/testing/selftests/bpf/DENYLIST.aarch64 +++ b/tools/testing/selftests/bpf/DENYLIST.aarch64 @@ -1,6 +1,5 @@ bpf_cookie/multi_kprobe_attach_api # kprobe_multi_link_api_subtest:FAIL:fentry_raw_skel_load unexpected error: -3 bpf_cookie/multi_kprobe_link_api # kprobe_multi_link_api_subtest:FAIL:fentry_raw_skel_load unexpected error: -3 -fexit_sleep # The test never returns. The remaining tests cannot start. kprobe_multi_bench_attach # needs CONFIG_FPROBE kprobe_multi_test # needs CONFIG_FPROBE module_attach # prog 'kprobe_multi': failed to auto-attach: -95 diff --git a/tools/testing/selftests/bpf/prog_tests/fexit_sleep.c b/tools/testing/selftests/bpf/prog_tests/fexit_sleep.c index f949647dbbc21..552a0875ca6db 100644 --- a/tools/testing/selftests/bpf/prog_tests/fexit_sleep.c +++ b/tools/testing/selftests/bpf/prog_tests/fexit_sleep.c @@ -21,13 +21,13 @@ static int do_sleep(void *skel) }
#define STACK_SIZE (1024 * 1024) -static char child_stack[STACK_SIZE];
void test_fexit_sleep(void) { struct fexit_sleep_lskel *fexit_skel = NULL; int wstatus, duration = 0; pid_t cpid; + char *child_stack = NULL; int err, fexit_cnt;
fexit_skel = fexit_sleep_lskel__open_and_load(); @@ -38,6 +38,11 @@ void test_fexit_sleep(void) if (CHECK(err, "fexit_attach", "fexit attach failed: %d\n", err)) goto cleanup;
+ child_stack = mmap(NULL, STACK_SIZE, PROT_READ | PROT_WRITE, MAP_PRIVATE | + MAP_ANONYMOUS | MAP_STACK, -1, 0); + if (!ASSERT_NEQ(child_stack, MAP_FAILED, "mmap")) + goto cleanup; + cpid = clone(do_sleep, child_stack + STACK_SIZE, CLONE_FILES | SIGCHLD, fexit_skel); if (CHECK(cpid == -1, "clone", "%s\n", strerror(errno))) goto cleanup; @@ -78,5 +83,6 @@ void test_fexit_sleep(void) goto cleanup;
cleanup: + munmap(child_stack, STACK_SIZE); fexit_sleep_lskel__destroy(fexit_skel); }