Re: [PATCHv8 09/11] selftests/x86/lam: Add mmap and SYSCALL test cases for linear-address masking

[Robert Hoo]

On Tue, 2022-08-30 at 04:01 +0300, Kirill A. Shutemov wrote:
> From: Weihong Zhang <weihong.zhang@xxxxxxxxx>
> 
> Add mmap and SYSCALL test cases.
> 
> SYSCALL test cases:
> 
>  - LAM supports set metadata in high bits 62:57 (LAM_U57) of a user
> pointer, pass
>    the pointer to SYSCALL, SYSCALL can dereference the pointer and
> return correct
>    result.
> 
>  - Disable LAM, pass a pointer with metadata in high bits to SYSCALL,
>    SYSCALL returns -1 (EFAULT).
> 
> MMAP test cases:
> 
>  - Enable LAM_U57, MMAP with low address (below bits 47), set
> metadata
>    in high bits of the address, dereference the address should be
>    allowed.
> 
>  - Enable LAM_U57, MMAP with high address (above bits 47), set
> metadata
>    in high bits of the address, dereference the address should be
>    allowed.
> 
> Signed-off-by: Weihong Zhang <weihong.zhang@xxxxxxxxx>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
> Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
> ---
>  tools/testing/selftests/x86/lam.c | 135
> +++++++++++++++++++++++++++++-
>  1 file changed, 132 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/testing/selftests/x86/lam.c
> b/tools/testing/selftests/x86/lam.c
> index 900a3a0fb709..b88e007ee0a3 100644
> --- a/tools/testing/selftests/x86/lam.c
> +++ b/tools/testing/selftests/x86/lam.c
> @@ -7,6 +7,7 @@
>  #include <signal.h>
>  #include <setjmp.h>
>  #include <sys/mman.h>
> +#include <sys/utsname.h>
>  #include <sys/wait.h>
>  #include <inttypes.h>
>  
> @@ -29,11 +30,18 @@
>  /* Specified test function bits */
>  #define FUNC_MALLOC             0x1
>  #define FUNC_BITS               0x2
> +#define FUNC_MMAP               0x4
> +#define FUNC_SYSCALL            0x8
>  
> -#define TEST_MASK               0x3
> +#define TEST_MASK               0xf
> +
> +#define LOW_ADDR                (0x1UL << 30)
> +#define HIGH_ADDR               (0x3UL << 48)
>  
>  #define MALLOC_LEN              32
>  
> +#define PAGE_SIZE               (4 << 10)
> +
>  struct testcases {
>  	unsigned int later;
>  	int expected; /* 2: SIGSEGV Error; 1: other errors */
> @@ -49,6 +57,7 @@ jmp_buf segv_env;
>  static void segv_handler(int sig)
>  {
>  	ksft_print_msg("Get segmentation fault(%d).", sig);
> +
>  	siglongjmp(segv_env, 1);
>  }
>  
> @@ -61,6 +70,16 @@ static inline int cpu_has_lam(void)
>  	return (cpuinfo[0] & (1 << 26));
>  }
>  
> +/* Check 5-level page table feature in CPUID.(EAX=07H,
> ECX=00H):ECX.[bit 16] */
> +static inline int cpu_has_la57(void)
> +{
> +	unsigned int cpuinfo[4];
> +
> +	__cpuid_count(0x7, 0, cpuinfo[0], cpuinfo[1], cpuinfo[2],
> cpuinfo[3]);
> +
> +	return (cpuinfo[2] & (1 << 16));
> +}
> +
>  /*
>   * Set tagged address and read back untag mask.
>   * check if the untagged mask is expected.
> @@ -213,6 +232,68 @@ static int handle_malloc(struct testcases *test)
>  	return ret;
>  }
>  
> +static int handle_mmap(struct testcases *test)
> +{
> +	void *ptr;
> +	unsigned int flags = MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED;
> +	int ret = 0;
> +
> +	if (test->later == 0 && test->lam != 0)
> +		if (set_lam(test->lam) != 0)
> +			return 1;
> +
> +	ptr = mmap((void *)test->addr, PAGE_SIZE, PROT_READ |
> PROT_WRITE,
> +		   flags, -1, 0);
> +	if (ptr == MAP_FAILED) {
> +		if (test->addr == HIGH_ADDR)
> +			if (!cpu_has_la57())
> +				return 3; /* unsupport LA57 */

I think here return 3 to indicate skip cases.

Perhaps you can enable skip case like this? Just FYI, I'm not familiar
with selftests yet.

@@ -321,8 +323,10 @@ static int handle_mmap(struct testcases *test)
                   flags, -1, 0);
        if (ptr == MAP_FAILED) {
                if (test->addr == HIGH_ADDR)
-                       if (!cpu_has_la57())
+                       if (!cpu_has_la57()) {
+                               perror("Unsupport LA57. Skip");
                                return 3; /* unsupport LA57 */
+                       }
                return 1;
        }
 
@@ -746,12 +750,16 @@ static void run_test(struct testcases *test, int
count)
 
                /* fork a process to run test case */
                ret = fork_test(t);
+               tests_cnt++;
+               if (ret == 3) {
+                       ksft_test_result_skip(t->msg);
+                       continue;
+               }
                if (ret != 0)
                        ret = (t->expected == ret);
                else
                        ret = !(t->expected);
 
-               tests_cnt++;
                ksft_test_result(ret, t->msg);
        }
 }

> +		return 1;
> +	}
> +
> +	if (test->later != 0 && test->lam != 0)
> +		if (set_lam(test->lam) != 0)
> +			ret = 1;
> +
> +	if (ret == 0) {
> +		if (sigsetjmp(segv_env, 1) == 0) {
> +			signal(SIGSEGV, segv_handler);
> +			ret = handle_lam_test(ptr, test->lam);
> +		} else {
> +			ret = 2;
> +		}
> +	}
> +
> +	munmap(ptr, PAGE_SIZE);
> +	return ret;
> +}
> +
> +static int handle_syscall(struct testcases *test)
> +{
> +	struct utsname unme, *pu;
> +	int ret = 0;
> +
> +	if (test->later == 0 && test->lam != 0)
> +		if (set_lam(test->lam) != 0)
> +			return 1;
> +
> +	if (sigsetjmp(segv_env, 1) == 0) {
> +		signal(SIGSEGV, segv_handler);
> +		pu = (struct utsname *)set_metadata((uint64_t)&unme,
> test->lam);
> +		ret = uname(pu);
> +		if (ret < 0)
> +			ret = 1;
> +	} else {
> +		ret = 2;
> +	}
> +
> +	if (test->later != 0 && test->lam != 0)
> +		if (set_lam(test->lam) != -1 && ret == 0)
> +			ret = 1;
> +
> +	return ret;
> +}
> +
>  static int fork_test(struct testcases *test)
>  {
>  	int ret, child_ret;
> @@ -268,7 +349,6 @@ static struct testcases malloc_cases[] = {
>  	},
>  };
>  
> -
>  static struct testcases bits_cases[] = {
>  	{
>  		.test_func = handle_max_bits,
> @@ -276,11 +356,54 @@ static struct testcases bits_cases[] = {
>  	},
>  };
>  
> +static struct testcases syscall_cases[] = {
> +	{
> +		.later = 0,
> +		.lam = LAM_U57_BITS,
> +		.test_func = handle_syscall,
> +		.msg = "SYSCALL: LAM_U57. syscall with metadata\n",
> +	},
> +	{
> +		.later = 1,
> +		.expected = 1,
> +		.lam = LAM_U57_BITS,
> +		.test_func = handle_syscall,
> +		.msg = "SYSCALL:[Negative] Disable LAM. Dereferencing
> pointer with metadata.\n",
> +	},
> +};
> +
> +static struct testcases mmap_cases[] = {
> +	{
> +		.later = 1,
> +		.expected = 0,
> +		.lam = LAM_U57_BITS,
> +		.addr = HIGH_ADDR,
> +		.test_func = handle_mmap,
> +		.msg = "MMAP: First mmap high address, then set
> LAM_U57.\n",
> +	},
> +	{
> +		.later = 0,
> +		.expected = 0,
> +		.lam = LAM_U57_BITS,
> +		.addr = HIGH_ADDR,
> +		.test_func = handle_mmap,
> +		.msg = "MMAP: First LAM_U57, then High address.\n",
> +	},
> +	{
> +		.later = 0,
> +		.expected = 0,
> +		.lam = LAM_U57_BITS,
> +		.addr = LOW_ADDR,
> +		.test_func = handle_mmap,
> +		.msg = "MMAP: First LAM_U57, then Low address.\n",
> +	},
> +};
> +
>  static void cmd_help(void)
>  {
>  	printf("usage: lam [-h] [-t test list]\n");
>  	printf("\t-t test list: run tests specified in the test list,
> default:0x%x\n", TEST_MASK);
> -	printf("\t\t0x1:malloc; 0x2:max_bits;\n");
> +	printf("\t\t0x1:malloc; 0x2:max_bits; 0x4:mmap;
> 0x8:syscall.\n");
>  	printf("\t-h: help\n");
>  }
>  
> @@ -320,6 +443,12 @@ int main(int argc, char **argv)
>  	if (tests & FUNC_BITS)
>  		run_test(bits_cases, ARRAY_SIZE(bits_cases));
>  
> +	if (tests & FUNC_MMAP)
> +		run_test(mmap_cases, ARRAY_SIZE(mmap_cases));
> +
> +	if (tests & FUNC_SYSCALL)
> +		run_test(syscall_cases, ARRAY_SIZE(syscall_cases));
> +
>  	ksft_set_plan(tests_cnt);
>  
>  	return ksft_exit_pass();