Re: [PATCH v2] selftests/ptrace/get_syscall_info: fix for MIPS n32

On 1/15/25 16:37, Dmitry V. Levin wrote:

MIPS n32 is one of two ILP32 architectures supported by the kernel that have 64-bit syscall arguments (another one is x32).

When this test passed 32-bit arguments to syscall(), they were sign-extended in libc, PTRACE_GET_SYSCALL_INFO reported these sign-extended 64-bit values, and the test complained about the mismatch.

Fix this by passing arguments of the appropriate type to syscall(), which is "unsigned long long" on MIPS n32, and __kernel_ulong_t on other architectures.

As a side effect, this also extends the test on all 64-bit architectures by choosing constants that don't fit into 32-bit integers.

Signed-off-by: Dmitry V. Levin ldv@strace.io

v2: Fixed MIPS #ifdef.

.../selftests/ptrace/get_syscall_info.c | 53 +++++++++++-------- 1 file changed, 32 insertions(+), 21 deletions(-)

diff --git a/tools/testing/selftests/ptrace/get_syscall_info.c b/tools/testing/selftests/ptrace/get_syscall_info.c index 5bcd1c7b5be6..2970f72d66d3 100644 --- a/tools/testing/selftests/ptrace/get_syscall_info.c +++ b/tools/testing/selftests/ptrace/get_syscall_info.c @@ -11,8 +11,19 @@ #include <err.h> #include <signal.h> #include <asm/unistd.h> +#include <linux/types.h> #include "linux/ptrace.h" +#if defined(_MIPS_SIM) && _MIPS_SIM == _MIPS_SIM_NABI32 +/*

• • MIPS N32 is the only architecture where __kernel_ulong_t
• • does not match the bitness of syscall arguments.
• */

+typedef unsigned long long kernel_ulong_t; +#else +typedef __kernel_ulong_t kernel_ulong_t; +#endif

What's the reason for adding these typedefs? checkpatch should have warned you about adding new typedefs.

Also this introduces kernel_ulong_t in user-space test code. Something to avoid.

static int kill_tracee(pid_t pid) { @@ -42,37 +53,37 @@ sys_ptrace(int request, pid_t pid, unsigned long addr, unsigned long data) TEST(get_syscall_info) {

• static const unsigned long args[][7] = {

• const kernel_ulong_t args[][7] = { /* a sequence of architecture-agnostic syscalls */ { __NR_chdir,

• 	(unsigned long) "",
  

• 	0xbad1fed1,
  

• 	0xbad2fed2,
  

• 	0xbad3fed3,
  

• 	0xbad4fed4,
  

• 	0xbad5fed5
  

• 	(uintptr_t) "",
  

You could use ifdef here.

• 	(kernel_ulong_t) 0xdad1bef1bad1fed1ULL,
  

• 	(kernel_ulong_t) 0xdad2bef2bad2fed2ULL,
  

• 	(kernel_ulong_t) 0xdad3bef3bad3fed3ULL,
  

• 	(kernel_ulong_t) 0xdad4bef4bad4fed4ULL,
  

• 	(kernel_ulong_t) 0xdad5bef5bad5fed5ULL
  

  }, { __NR_gettid,

• 	0xcaf0bea0,
  

• 	0xcaf1bea1,
  

• 	0xcaf2bea2,
  

• 	0xcaf3bea3,
  

• 	0xcaf4bea4,
  

• 	0xcaf5bea5
  

• 	(kernel_ulong_t) 0xdad0bef0caf0bea0ULL,
  

• 	(kernel_ulong_t) 0xdad1bef1caf1bea1ULL,
  

• 	(kernel_ulong_t) 0xdad2bef2caf2bea2ULL,
  

• 	(kernel_ulong_t) 0xdad3bef3caf3bea3ULL,
  

• 	(kernel_ulong_t) 0xdad4bef4caf4bea4ULL,
  

• 	(kernel_ulong_t) 0xdad5bef5caf5bea5ULL
  

  }, { __NR_exit_group, 0,

• 	0xfac1c0d1,
  

• 	0xfac2c0d2,
  

• 	0xfac3c0d3,
  

• 	0xfac4c0d4,
  

• 	0xfac5c0d5
  

• 	(kernel_ulong_t) 0xdad1bef1fac1c0d1ULL,
  

• 	(kernel_ulong_t) 0xdad2bef2fac2c0d2ULL,
  

• 	(kernel_ulong_t) 0xdad3bef3fac3c0d3ULL,
  

• 	(kernel_ulong_t) 0xdad4bef4fac4c0d4ULL,
  

• 	(kernel_ulong_t) 0xdad5bef5fac5c0d5ULL
  

  } };

• const unsigned long *exp_args;

• const kernel_ulong_t *exp_args;

pid_t pid = fork(); @@ -154,7 +165,7 @@ TEST(get_syscall_info) } ASSERT_LT(0, (rc = sys_ptrace(PTRACE_GET_SYSCALL_INFO, pid, size,

• 				      (unsigned long) &info))) {
  

• 				      (uintptr_t) &info))) {
  	LOG_KILL_TRACEE("PTRACE_GET_SYSCALL_INFO: %m");
  }
  ASSERT_EQ(expected_none_size, rc) {
  

@@ -177,7 +188,7 @@ TEST(get_syscall_info) case SIGTRAP | 0x80: ASSERT_LT(0, (rc = sys_ptrace(PTRACE_GET_SYSCALL_INFO, pid, size,

• 				      (unsigned long) &info))) {
  

• 				      (uintptr_t) &info))) {
  	LOG_KILL_TRACEE("PTRACE_GET_SYSCALL_INFO: %m");
  }
  switch (ptrace_stop) {
  

thanks, -- Shuah