With 5-level paging, we have 56-bit virtual address space available for
userspace. But we don't want to expose userspace to addresses above
47-bits, unless it asked specifically for it.
We use mmap(2) hint address as a way for kernel to know if it's okay to
allocate virtual memory above 47-bit.
Let's add a self-test that covers few corner cases of the interface.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
---
tools/testing/selftests/x86/5lvl.c | 53 ++++++++++++++++++++++++++++++++++++
tools/testing/selftests/x86/Makefile | 2 +-
2 files changed, 54 insertions(+), 1 deletion(-)
create mode 100644 tools/testing/selftests/x86/5lvl.c
diff --git a/tools/testing/selftests/x86/5lvl.c b/tools/testing/selftests/x86/5lvl.c
new file mode 100644
index 000000000000..94610fd13ba2
--- /dev/null
+++ b/tools/testing/selftests/x86/5lvl.c
@@ -0,0 +1,53 @@
+#include <stdio.h>
+#include <sys/mman.h>
+
+#define PAGE_SIZE 4096
+#define SIZE (2 * PAGE_SIZE)
+#define LOW_ADDR ((void *) (1UL << 30))
+#define HIGH_ADDR ((void *) (1UL << 50))
+#define TASK_SIZE ((void *) (1UL << 47))
+
+int main(int argc, char **argv)
+{
+ void *p;
+
+ p = mmap(NULL, SIZE, PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+ printf("mmap(NULL): %p %s\n", p, p > TASK_SIZE ? "FAILED!" : "");
+
+ p = mmap(LOW_ADDR, SIZE, PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+ printf("mmap(%p): %p %s\n", LOW_ADDR, p,
+ p > TASK_SIZE ? "FAILED!" : "");
+
+ p = mmap(HIGH_ADDR, SIZE, PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+ printf("mmap(%p): %p\n", HIGH_ADDR, p);
+
+ p = mmap(HIGH_ADDR, SIZE, PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+ printf("mmap(%p) again: %p\n", HIGH_ADDR, p);
+
+ p = mmap(HIGH_ADDR, SIZE, PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, -1, 0);
+ printf("mmap(%p, MAP_FIXED): %p\n", HIGH_ADDR, p);
+
+ p = mmap((void *)-1, SIZE, PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+ printf("mmap(-1): %p\n", p);
+
+ p = mmap((void *)-1, SIZE, PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+ printf("mmap(-1) again: %p\n", p);
+
+ p = mmap(TASK_SIZE - PAGE_SIZE, SIZE, PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+ printf("mmap(%p, %d): %p %s\n", TASK_SIZE - PAGE_SIZE, SIZE, p,
+ p > TASK_SIZE ? "FAILED!" : "");
+
+ p = mmap(TASK_SIZE - PAGE_SIZE, SIZE, PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, -1, 0);
+ printf("mmap(TASK_SIZE - PAGE_SIZE, MAP_FIXED): %p\n", p);
+
+ return 0;
+}
diff --git a/tools/testing/selftests/x86/Makefile b/tools/testing/selftests/x86/Makefile
index 0a74a20ca32b..1f5d6565fbef 100644
--- a/tools/testing/selftests/x86/Makefile
+++ b/tools/testing/selftests/x86/Makefile
@@ -10,7 +10,7 @@ TARGETS_C_BOTHBITS := single_step_syscall sysret_ss_attrs syscall_nt ptrace_sysc
TARGETS_C_32BIT_ONLY := entry_from_vm86 syscall_arg_fault test_syscall_vdso unwind_vdso \
test_FCMOV test_FCOMI test_FISTTP \
vdso_restorer
-TARGETS_C_64BIT_ONLY := fsgsbase sysret_rip
+TARGETS_C_64BIT_ONLY := fsgsbase sysret_rip 5lvl
TARGETS_C_32BIT_ALL := $(TARGETS_C_BOTHBITS) $(TARGETS_C_32BIT_ONLY)
TARGETS_C_64BIT_ALL := $(TARGETS_C_BOTHBITS) $(TARGETS_C_64BIT_ONLY)
--
2.14.2
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