selftests/ptrace/get_syscall_info: fix for MIPS n32

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 <[email protected]>

---

v2: Fixed MIPS #ifdef.

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

tools/testing/selftests/ptrace/get_syscall_info.c +32 -21

index 5bcd1c7b5be6..2970f72d66d3 100644
@@ -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
+
 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) "",
+			(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) {

Signature · 1 line

ldv

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 <[email protected]>

---

v2: Fixed MIPS #ifdef.

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

tools/testing/selftests/ptrace/get_syscall_info.c +1 -0

index 5bcd1c7b5be6..2970f72d66d3 100644
@@ -11,8 +11,19 @@
  #include <err.h>
  #include <signal.h>
  #include <asm/unistd.h>
+#include <linux/types.h>
  #include "linux/ptrace.h"
 

tools/testing/selftests/ptrace/get_syscall_info.c +1 -1

  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] = {

tools/testing/selftests/ptrace/get_syscall_info.c +18 -13

+			(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) {

Quoted 33 lines · Dmitry V. Levin

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 <[email protected]>

---

v2: Fixed MIPS #ifdef.

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

tools/testing/selftests/ptrace/get_syscall_info.c +1 -0

index 5bcd1c7b5be6..2970f72d66d3 100644
@@ -11,8 +11,19 @@
  #include <err.h>
  #include <signal.h>
  #include <asm/unistd.h>
+#include <linux/types.h>
  #include "linux/ptrace.h"
 

tools/testing/selftests/ptrace/get_syscall_info.c line 26

Quoted 10 lines

tools/testing/selftests/ptrace/get_syscall_info.c +10 -0

+#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.

Quoted 5 lines

tools/testing/selftests/ptrace/get_syscall_info.c +0 -0

  static int
  kill_tracee(pid_t pid)
  {

@@ -42,37 +53,37 @@ sys_ptrace(int request, pid_t pid, unsigned long addr, unsigned long data)
 

Quoted 4 lines

tools/testing/selftests/ptrace/get_syscall_info.c +1 -1

  TEST(get_syscall_info)
  {
-	static const unsigned long args[][7] = {
+	const kernel_ulong_t args[][7] = {

tools/testing/selftests/ptrace/get_syscall_info.c sys_ptrace(int request, pid_t pid, unsigned long addr, unsigned long data) · line 60

Quoted 10 lines

tools/testing/selftests/ptrace/get_syscall_info.c +1 -6

  		/* a sequence of architecture-agnostic syscalls */
  		{
  			__NR_chdir,
-			(unsigned long) "",
-			0xbad1fed1,
-			0xbad2fed2,
-			0xbad3fed3,
-			0xbad4fed4,
-			0xbad5fed5
+			(uintptr_t) "",

You could use ifdef here.

Quoted 14 lines

tools/testing/selftests/ptrace/get_syscall_info.c line 26

Quoted 10 lines

tools/testing/selftests/ptrace/get_syscall_info.c +10 -0

+#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.

Quoted 2 lines

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

There has to be a new type for this test, and the natural way to do this is to use typedef. The alternative would be to #define kernel_ulong_t which is ugly. By the way, there are quite a few typedefs in selftests, and there seems to be given no rationale why adding new types in selftests is a bad idea.

Quoted 14 lines · Dmitry V. Levin

Quoted 14 lines

tools/testing/selftests/ptrace/get_syscall_info.c line 26

Quoted 10 lines

tools/testing/selftests/ptrace/get_syscall_info.c +10 -0

+#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.

Quoted 8 lines

Quoted 2 lines

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

There has to be a new type for this test, and the natural way to do this is to use typedef. The alternative would be to #define kernel_ulong_t which is ugly. By the way, there are quite a few typedefs in selftests, and there seems to be given no rationale why adding new types in selftests is a bad idea.

FWIW I agree, and I fail to see a reason why this would be a problem in a
standalone test program where the typedef does not propagate anywhere.

The only potential issue I can identify would be a namespace clash, so
perhaps the new type could have a name prefix specific to the test, but it doesn't appear to me a widespread practice across our selftests and then `kernel_' ought to be pretty safe against ISO C or POSIX, so perhaps let's leave the things alone?

Quoted 14 lines · Dmitry V. Levin

Quoted 14 lines

tools/testing/selftests/ptrace/get_syscall_info.c line 26

Quoted 10 lines

tools/testing/selftests/ptrace/get_syscall_info.c +10 -0

+#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.

Quoted 8 lines

Quoted 2 lines

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

There has to be a new type for this test, and the natural way to do this is to use typedef. The alternative would be to #define kernel_ulong_t which is ugly. By the way, there are quite a few typedefs in selftests, and there seems to be given no rationale why adding new types in selftests is a bad idea.

FWIW I agree, and I fail to see a reason why this would be a problem in a
standalone test program where the typedef does not propagate anywhere.

The only potential issue I can identify would be a namespace clash, so
perhaps the new type could have a name prefix specific to the test, but it doesn't appear to me a widespread practice across our selftests and then `kernel_' ought to be pretty safe against ISO C or POSIX, so perhaps let's leave the things alone?

Quoted 25 lines · Maciej W. Rozycki

Quoted 14 lines · Dmitry V. Levin

Quoted 14 lines

tools/testing/selftests/ptrace/get_syscall_info.c line 26

Quoted 10 lines

tools/testing/selftests/ptrace/get_syscall_info.c +10 -0

+#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.

Quoted 8 lines

Quoted 2 lines

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

There has to be a new type for this test, and the natural way to do this is to use typedef. The alternative would be to #define kernel_ulong_t which is ugly. By the way, there are quite a few typedefs in selftests, and there seems to be given no rationale why adding new types in selftests is a bad idea.

Quoted 8 lines

FWIW I agree, and I fail to see a reason why this would be a problem in a
standalone test program where the typedef does not propagate anywhere.

The only potential issue I can identify would be a namespace clash, so
perhaps the new type could have a name prefix specific to the test, but it doesn't appear to me a widespread practice across our selftests and then `kernel_' ought to be pretty safe against ISO C or POSIX, so perhaps let's leave the things alone?

Another similar test I authored (selftests/ptrace/set_syscall_info) has been merged, so there are two similar tests in the tree now, but only one of them is permitted to use this approach, creating inconsistency.

Taking all of the above into consideration, please approve this fix.