[linux-morello] Re: [PATCH v4 3/3] kselftests/arm64: morello: clone: Remove loop check

On 3/23/23 15:12, Kevin Brodsky wrote:

On 23/03/2023 07:56, Amit Daniel Kachhap wrote:

...

Some of the clone tests use loop check on status flag to determine if the child exited normally. However, this may cause infinite looping if the data handshake does not happen properly between parent and child due to compiler optimization as observed with Morello Gcc.

Although this can be fixed by setting the flag to volatile but here we replace the busy loop with the waitpid() syscall to wait for the child to exit before parent is executed. This approach allows us to get rid of item status and result from struct test_fixture.

Signed-off-by: Amit Daniel Kachhap amit.kachhap@arm.com

tools/testing/selftests/arm64/morello/clone.c | 36 +++++++------------ .../selftests/arm64/morello/freestanding.h | 7 ++++ 2 files changed, 19 insertions(+), 24 deletions(-)

diff --git a/tools/testing/selftests/arm64/morello/clone.c b/tools/testing/selftests/arm64/morello/clone.c index 60514fa5f869..68d32261c8de 100644 --- a/tools/testing/selftests/arm64/morello/clone.c +++ b/tools/testing/selftests/arm64/morello/clone.c @@ -18,16 +18,13 @@ #define in_restricted() \ (!(cheri_perms_get(cheri_pcc_get()) & ARM_CAP_PERMISSION_EXECUTIVE))

-#define MAGIC_NR 0x3562 /* whatever really ..... */

• #ifndef MAX_PID_NS_LEVEL #define MAX_PID_NS_LEVEL 32 #endif

/* Cloned thread result */ -#define CTR_SUCCESS 1 -#define CTR_FAILED -1 +#define CTR_SUCCESS 0 +#define CTR_FAILED 1 #define BIT(nr) ((1U) << (nr)) /* Test flags */ @@ -36,10 +33,8 @@ #define CLONE_TH_RUSAGE BIT(3) struct test_fixture {

• int status; int flags; void *sp;
• int result; };

#define PROBE_INTERVAL (1 << 12) @@ -76,27 +71,21 @@ static int clone_base_fn(void *data) asm("mrs %0, ctpidr_el0" : "=C" (tls));

• if (!tls) {
  

• 	__data->result = CTR_FAILED;
  

• 	goto done;
  

• }
  

• if (!tls)
  

• 	return CTR_FAILED;
  

probe_addr_range(tls, STACK_SIZE >> 10, 64); } /* If things didn't explode by now .... */

• __data->result =

• !!(__data->flags & CLONE_TH_RESTRICTED) != in_restricted() ?
  

•  CTR_FAILED : CTR_SUCCESS;
  

-done:

• __data->status = MAGIC_NR;
• return 0;

• return !!(__data->flags & CLONE_TH_RESTRICTED) != in_restricted() ?

•       CTR_FAILED : CTR_SUCCESS;
  

  }

static inline __attribute__((always_inline)) void clone_single(struct test_fixture *data) {

• int ppid = 0, cpid = 0;

• int ppid = 0, cpid = 0, wstatus; int result = -EINVAL;

void *new_stack = mmap_verified(NULL, STACK_SIZE, PROT_READ | PROT_WRITE, @@ -107,7 +96,7 @@ void clone_single(struct test_fixture *data) CAP_LOAD_PERMS | CAP_STORE_PERMS) : NULL;

• int clone_flags = CLONE_VM | CLONE_PARENT_SETTID | CLONE_CHILD_SETTID;

• int clone_flags = CLONE_VM | CLONE_PARENT_SETTID | CLONE_CHILD_SETTID | SIGCHLD;

int (*clone_fn_ptr)(void *) = clone_base_fn; @@ -142,10 +131,9 @@ void clone_single(struct test_fixture *data) goto leave; }

• /* Wait substitute ... */
• while (data->status != MAGIC_NR) {

• asm("");
  

• }

• /* Wait for the child to exit */
• result = waitpid(cpid, &wstatus, 0);
• ASSERT_EQ(result, cpid); /*
  • CLONE_CHILD_SETTID sets child's thread ID to provided child's
  • memory but as VM is being shared, it's all good at this point.

@@ -153,7 +141,7 @@ void clone_single(struct test_fixture *data) * Either way if this point has been reached - all went 'supposedly' * well. */

It's no longer clear to me what this comment is getting at. I asked Beata separately and she can't recall either, so I suggest we remove it as part of this patch.

Happy with the series otherwise so I can make this change when merging if that sounds alright.

Ok please go ahead. The comments sounds confusing.

//Amit

Kevin

...

• ASSERT_EQ(data->result, CTR_SUCCESS);

• ASSERT_TRUE(WIFEXITED(wstatus) && (WEXITSTATUS(wstatus) == CTR_SUCCESS)); leave: munmap(new_stack, STACK_SIZE); if (tls)

diff --git a/tools/testing/selftests/arm64/morello/freestanding.h b/tools/testing/selftests/arm64/morello/freestanding.h index 0b0de05d46bc..2beb52eafae1 100644 --- a/tools/testing/selftests/arm64/morello/freestanding.h +++ b/tools/testing/selftests/arm64/morello/freestanding.h @@ -31,6 +31,13 @@ typedef __uintcap_t uintcap_t; #define EXIT_SUCCESS 0 +#ifndef WIFEXITED +#define WIFEXITED(status) (((status) & 0x7f) == 0) +#endif +#ifndef WEXITSTATUS +#define WEXITSTATUS(status) (((status) & 0xff00) >> 8) +#endif

• struct __test_meta { int message; };