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

[Zhang, Weihong]

> -----Original Message-----
> From: Robert Hoo <robert.hu@xxxxxxxxxxxxxxx>
> Sent: Wednesday, September 7, 2022 11:20 AM
> To: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>; Dave Hansen
> <dave.hansen@xxxxxxxxxxxxxxx>; Lutomirski, Andy <luto@xxxxxxxxxx>; Peter
> Zijlstra <peterz@xxxxxxxxxxxxx>
> Cc: x86@xxxxxxxxxx; Kostya Serebryany <kcc@xxxxxxxxxx>; Andrey Ryabinin
> <ryabinin.a.a@xxxxxxxxx>; Andrey Konovalov <andreyknvl@xxxxxxxxx>;
> Alexander Potapenko <glider@xxxxxxxxxx>; Taras Madan
> <tarasmadan@xxxxxxxxxx>; Dmitry Vyukov <dvyukov@xxxxxxxxxx>; H . J .
> Lu <hjl.tools@xxxxxxxxx>; Andi Kleen <ak@xxxxxxxxxxxxxxx>; Edgecombe,
> Rick P <rick.p.edgecombe@xxxxxxxxx>; linux-mm@xxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx; Zhang, Weihong <weihong.zhang@xxxxxxxxx>
> Subject: Re: [PATCHv8 09/11] selftests/x86/lam: Add mmap and SYSCALL
> test cases for linear-address masking
> 
> 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.
> 
Yes, this case can be regarded as skip case.

> @@ -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();