diff options
| author | Maciej Wieczor-Retman <maciej.wieczor-retman@intel.com> | 2025-01-27 16:31:55 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2025-02-22 13:17:07 +0100 |
| commit | ec8f5b4659b4044db55e1f7d947703dd4948626c (patch) | |
| tree | d7e94201e2dfda796639784b9be02ed1a81c066c | |
| parent | 7ffb791423c7c518269a9aad35039ef824a40adb (diff) | |
selftests/lam: Move cpu_has_la57() to use cpuinfo flag
In current form cpu_has_la57() reports platform's support for LA57
through reading the output of cpuid. A much more useful information is
whether 5-level paging is actually enabled on the running system.
Check whether 5-level paging is enabled by trying to map a page in the
high linear address space.
Signed-off-by: Maciej Wieczor-Retman <maciej.wieczor-retman@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Link: https://lore.kernel.org/r/8b1ca51b13e6d94b5a42b6930d81b692cbb0bcbb.1737990375.git.maciej.wieczor-retman@intel.com
| -rw-r--r-- | tools/testing/selftests/x86/lam.c | 16 |
1 files changed, 10 insertions, 6 deletions
diff --git a/tools/testing/selftests/x86/lam.c b/tools/testing/selftests/x86/lam.c index 4d4a76532dc9..60170a31aa69 100644 --- a/tools/testing/selftests/x86/lam.c +++ b/tools/testing/selftests/x86/lam.c @@ -124,14 +124,18 @@ 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) +static inline int la57_enabled(void) { - unsigned int cpuinfo[4]; + int ret; + void *p; + + p = mmap((void *)HIGH_ADDR, PAGE_SIZE, PROT_READ | PROT_WRITE, + MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, -1, 0); - __cpuid_count(0x7, 0, cpuinfo[0], cpuinfo[1], cpuinfo[2], cpuinfo[3]); + ret = p == MAP_FAILED ? 0 : 1; - return (cpuinfo[2] & (1 << 16)); + munmap(p, PAGE_SIZE); + return ret; } /* @@ -322,7 +326,7 @@ static int handle_mmap(struct testcases *test) flags, -1, 0); if (ptr == MAP_FAILED) { if (test->addr == HIGH_ADDR) - if (!cpu_has_la57()) + if (!la57_enabled()) return 3; /* unsupport LA57 */ return 1; } |