The encoding of the pkey register differs on arm64, than on x86/ppc. On those
platforms, a bit in the register is used to disable permissions, for arm64, a
bit enabled in the register indicates that the permission is allowed.
This drops two asserts of the form:
assert(read_pkey_reg() <= orig_pkey_reg);
Because on arm64 this doesn't hold, due to the encoding.
The pkey must be reset to both access allow and write allow in the signal
handler. pkey_access_allow() works currently for PowerPC as the
PKEY_DISABLE_ACCESS and PKEY_DISABLE_WRITE have overlapping bits set.
Access to the uc_mcontext is abstracted, as arm64 has a different structure.
Signed-off-by: Joey Gouly <joey.gouly@xxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Shuah Khan <shuah@xxxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
Acked-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
---
.../arm64/signal/testcases/testcases.h | 3 +
tools/testing/selftests/mm/Makefile | 2 +-
tools/testing/selftests/mm/pkey-arm64.h | 139 ++++++++++++++++++
tools/testing/selftests/mm/pkey-helpers.h | 8 +
tools/testing/selftests/mm/pkey-powerpc.h | 2 +
tools/testing/selftests/mm/pkey-x86.h | 2 +
tools/testing/selftests/mm/protection_keys.c | 103 +++++++++++--
7 files changed, 247 insertions(+), 12 deletions(-)
create mode 100644 tools/testing/selftests/mm/pkey-arm64.h
diff --git tools/testing/selftests/arm64/signal/testcases/testcases.h tools/testing/selftests/arm64/signal/testcases/testcases.h
index 3185e6875694..9872b8912714 100644
--- tools/testing/selftests/arm64/signal/testcases/testcases.h
+++ tools/testing/selftests/arm64/signal/testcases/testcases.h
@@ -26,6 +26,9 @@
#define HDR_SZ \
sizeof(struct _aarch64_ctx)
+#define GET_UC_RESV_HEAD(uc) \
+ (struct _aarch64_ctx *)(&(uc->uc_mcontext.__reserved))
+
#define GET_SF_RESV_HEAD(sf) \
(struct _aarch64_ctx *)(&(sf).uc.uc_mcontext.__reserved)
diff --git tools/testing/selftests/mm/Makefile tools/testing/selftests/mm/Makefile
index cfad627e8d94..5f2ca591c956 100644
--- tools/testing/selftests/mm/Makefile
+++ tools/testing/selftests/mm/Makefile
@@ -106,7 +106,7 @@ TEST_GEN_FILES += $(BINARIES_64)
endif
else
-ifneq (,$(findstring $(ARCH),powerpc))
+ifneq (,$(filter $(ARCH),arm64 powerpc))
TEST_GEN_FILES += protection_keys
endif
diff --git tools/testing/selftests/mm/pkey-arm64.h tools/testing/selftests/mm/pkey-arm64.h
new file mode 100644
index 000000000000..580e1b0bb38e
--- /dev/null
+++ tools/testing/selftests/mm/pkey-arm64.h
@@ -0,0 +1,139 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2023 Arm Ltd.
+ */
+
+#ifndef _PKEYS_ARM64_H
+#define _PKEYS_ARM64_H
+
+#include "vm_util.h"
+/* for signal frame parsing */
+#include "../arm64/signal/testcases/testcases.h"
+
+#ifndef SYS_mprotect_key
+# define SYS_mprotect_key 288
+#endif
+#ifndef SYS_pkey_alloc
+# define SYS_pkey_alloc 289
+# define SYS_pkey_free 290
+#endif
+#define MCONTEXT_IP(mc) mc.pc
+#define MCONTEXT_TRAPNO(mc) -1
+
+#define PKEY_MASK 0xf
+
+#define POE_NONE 0x0
+#define POE_X 0x2
+#define POE_RX 0x3
+#define POE_RWX 0x7
+
+#define NR_PKEYS 8
+#define NR_RESERVED_PKEYS 1 /* pkey-0 */
+
+#define PKEY_ALLOW_ALL 0x77777777
+
+#define PKEY_BITS_PER_PKEY 4
+#define PAGE_SIZE sysconf(_SC_PAGESIZE)
+#undef HPAGE_SIZE
+#define HPAGE_SIZE default_huge_page_size()
+
+/* 4-byte instructions * 16384 = 64K page */
+#define __page_o_noops() asm(".rept 16384 ; nop; .endr")
+
+static inline u64 __read_pkey_reg(void)
+{
+ u64 pkey_reg = 0;
+
+ // POR_EL0
+ asm volatile("mrs %0, S3_3_c10_c2_4" : "=r" (pkey_reg));
+
+ return pkey_reg;
+}
+
+static inline void __write_pkey_reg(u64 pkey_reg)
+{
+ u64 por = pkey_reg;
+
+ dprintf4("%s() changing %016llx to %016llx\n",
+ __func__, __read_pkey_reg(), pkey_reg);
+
+ // POR_EL0
+ asm volatile("msr S3_3_c10_c2_4, %0\nisb" :: "r" (por) :);
+
+ dprintf4("%s() pkey register after changing %016llx to %016llx\n",
+ __func__, __read_pkey_reg(), pkey_reg);
+}
+
+static inline int cpu_has_pkeys(void)
+{
+ /* No simple way to determine this */
+ return 1;
+}
+
+static inline u32 pkey_bit_position(int pkey)
+{
+ return pkey * PKEY_BITS_PER_PKEY;
+}
+
+static inline int get_arch_reserved_keys(void)
+{
+ return NR_RESERVED_PKEYS;
+}
+
+void expect_fault_on_read_execonly_key(void *p1, int pkey)
+{
+}
+
+void *malloc_pkey_with_mprotect_subpage(long size, int prot, u16 pkey)
+{
+ return PTR_ERR_ENOTSUP;
+}
+
+#define set_pkey_bits set_pkey_bits
+static inline u64 set_pkey_bits(u64 reg, int pkey, u64 flags)
+{
+ u32 shift = pkey_bit_position(pkey);
+ u64 new_val = POE_RWX;
+
+ /* mask out bits from pkey in old value */
+ reg &= ~((u64)PKEY_MASK << shift);
+
+ if (flags & PKEY_DISABLE_ACCESS)
+ new_val = POE_X;
+ else if (flags & PKEY_DISABLE_WRITE)
+ new_val = POE_RX;
+
+ /* OR in new bits for pkey */
+ reg |= new_val << shift;
+
+ return reg;
+}
+
+#define get_pkey_bits get_pkey_bits
+static inline u64 get_pkey_bits(u64 reg, int pkey)
+{
+ u32 shift = pkey_bit_position(pkey);
+ /*
+ * shift down the relevant bits to the lowest four, then
+ * mask off all the other higher bits
+ */
+ u32 perm = (reg >> shift) & PKEY_MASK;
+
+ if (perm == POE_X)
+ return PKEY_DISABLE_ACCESS;
+ if (perm == POE_RX)
+ return PKEY_DISABLE_WRITE;
+ return 0;
+}
+
+static void aarch64_write_signal_pkey(ucontext_t *uctxt, u64 pkey)
+{
+ struct _aarch64_ctx *ctx = GET_UC_RESV_HEAD(uctxt);
+ struct poe_context *poe_ctx =
+ (struct poe_context *) get_header(ctx, POE_MAGIC,
+ sizeof(uctxt->uc_mcontext), NULL);
+ if (poe_ctx)
+ poe_ctx->por_el0 = pkey;
+}
+
+#endif /* _PKEYS_ARM64_H */
diff --git tools/testing/selftests/mm/pkey-helpers.h tools/testing/selftests/mm/pkey-helpers.h
index 1af3156a9db8..15608350fc01 100644
--- tools/testing/selftests/mm/pkey-helpers.h
+++ tools/testing/selftests/mm/pkey-helpers.h
@@ -91,12 +91,17 @@ void record_pkey_malloc(void *ptr, long size, int prot);
#include "pkey-x86.h"
#elif defined(__powerpc64__) /* arch */
#include "pkey-powerpc.h"
+#elif defined(__aarch64__) /* arch */
+#include "pkey-arm64.h"
#else /* arch */
#error Architecture not supported
#endif /* arch */
+#ifndef PKEY_MASK
#define PKEY_MASK (PKEY_DISABLE_ACCESS | PKEY_DISABLE_WRITE)
+#endif
+#ifndef set_pkey_bits
static inline u64 set_pkey_bits(u64 reg, int pkey, u64 flags)
{
u32 shift = pkey_bit_position(pkey);
@@ -106,7 +111,9 @@ static inline u64 set_pkey_bits(u64 reg, int pkey, u64 flags)
reg |= (flags & PKEY_MASK) << shift;
return reg;
}
+#endif
+#ifndef get_pkey_bits
static inline u64 get_pkey_bits(u64 reg, int pkey)
{
u32 shift = pkey_bit_position(pkey);
@@ -116,6 +123,7 @@ static inline u64 get_pkey_bits(u64 reg, int pkey)
*/
return ((reg >> shift) & PKEY_MASK);
}
+#endif
extern u64 shadow_pkey_reg;
diff --git tools/testing/selftests/mm/pkey-powerpc.h tools/testing/selftests/mm/pkey-powerpc.h
index 6275d0f474b3..3d0c0bdae5bc 100644
--- tools/testing/selftests/mm/pkey-powerpc.h
+++ tools/testing/selftests/mm/pkey-powerpc.h
@@ -8,6 +8,8 @@
# define SYS_pkey_free 385
#endif
#define REG_IP_IDX PT_NIP
+#define MCONTEXT_IP(mc) mc.gp_regs[REG_IP_IDX]
+#define MCONTEXT_TRAPNO(mc) mc.gp_regs[REG_TRAPNO]
#define REG_TRAPNO PT_TRAP
#define MCONTEXT_FPREGS
#define gregs gp_regs
diff --git tools/testing/selftests/mm/pkey-x86.h tools/testing/selftests/mm/pkey-x86.h
index b9170a26bfcb..5f28e26a2511 100644
--- tools/testing/selftests/mm/pkey-x86.h
+++ tools/testing/selftests/mm/pkey-x86.h
@@ -15,6 +15,8 @@
#endif
+#define MCONTEXT_IP(mc) mc.gregs[REG_IP_IDX]
+#define MCONTEXT_TRAPNO(mc) mc.gregs[REG_TRAPNO]
#define MCONTEXT_FPREGS
#ifndef PKEY_DISABLE_ACCESS
diff --git tools/testing/selftests/mm/protection_keys.c tools/testing/selftests/mm/protection_keys.c
index 4337106a985e..0789981b72b9 100644
--- tools/testing/selftests/mm/protection_keys.c
+++ tools/testing/selftests/mm/protection_keys.c
@@ -147,7 +147,7 @@ void abort_hooks(void)
* will then fault, which makes sure that the fault code handles
* execute-only memory properly.
*/
-#ifdef __powerpc64__
+#if defined(__powerpc64__) || defined(__aarch64__)
/* This way, both 4K and 64K alignment are maintained */
__attribute__((__aligned__(65536)))
#else
@@ -212,7 +212,6 @@ void pkey_disable_set(int pkey, int flags)
unsigned long syscall_flags = 0;
int ret;
int pkey_rights;
- u64 orig_pkey_reg = read_pkey_reg();
dprintf1("START->%s(%d, 0x%x)\n", __func__,
pkey, flags);
@@ -242,8 +241,6 @@ void pkey_disable_set(int pkey, int flags)
dprintf1("%s(%d) pkey_reg: 0x%016llx\n",
__func__, pkey, read_pkey_reg());
- if (flags)
- pkey_assert(read_pkey_reg() >= orig_pkey_reg);
dprintf1("END<---%s(%d, 0x%x)\n", __func__,
pkey, flags);
}
@@ -253,7 +250,6 @@ void pkey_disable_clear(int pkey, int flags)
unsigned long syscall_flags = 0;
int ret;
int pkey_rights = hw_pkey_get(pkey, syscall_flags);
- u64 orig_pkey_reg = read_pkey_reg();
pkey_assert(flags & (PKEY_DISABLE_ACCESS | PKEY_DISABLE_WRITE));
@@ -273,8 +269,6 @@ void pkey_disable_clear(int pkey, int flags)
dprintf1("%s(%d) pkey_reg: 0x%016llx\n", __func__,
pkey, read_pkey_reg());
- if (flags)
- assert(read_pkey_reg() <= orig_pkey_reg);
}
void pkey_write_allow(int pkey)
@@ -330,8 +324,8 @@ void signal_handler(int signum, siginfo_t *si, void *vucontext)
__func__, __LINE__,
__read_pkey_reg(), shadow_pkey_reg);
- trapno = uctxt->uc_mcontext.gregs[REG_TRAPNO];
- ip = uctxt->uc_mcontext.gregs[REG_IP_IDX];
+ trapno = MCONTEXT_TRAPNO(uctxt->uc_mcontext);
+ ip = MCONTEXT_IP(uctxt->uc_mcontext);
#ifdef MCONTEXT_FPREGS
fpregs = (char *) uctxt->uc_mcontext.fpregs;
#endif
@@ -395,6 +389,8 @@ void signal_handler(int signum, siginfo_t *si, void *vucontext)
#elif defined(__powerpc64__) /* arch */
/* restore access and let the faulting instruction continue */
pkey_access_allow(siginfo_pkey);
+#elif defined(__aarch64__)
+ aarch64_write_signal_pkey(uctxt, PKEY_ALLOW_ALL);
#endif /* arch */
pkey_faults++;
dprintf1("<<<<==================================================\n");
@@ -908,7 +904,9 @@ void expected_pkey_fault(int pkey)
* test program continue. We now have to restore it.
*/
if (__read_pkey_reg() != 0)
-#else /* arch */
+#elif defined(__aarch64__)
+ if (__read_pkey_reg() != PKEY_ALLOW_ALL)
+#else
if (__read_pkey_reg() != shadow_pkey_reg)
#endif /* arch */
pkey_assert(0);
@@ -1498,6 +1496,11 @@ void test_executing_on_unreadable_memory(int *ptr, u16 pkey)
lots_o_noops_around_write(&scratch);
do_not_expect_pkey_fault("executing on PROT_EXEC memory");
expect_fault_on_read_execonly_key(p1, pkey);
+
+ // Reset back to PROT_EXEC | PROT_READ for architectures that support
+ // non-PKEY execute-only permissions.
+ ret = mprotect_pkey(p1, PAGE_SIZE, PROT_EXEC | PROT_READ, (u64)pkey);
+ pkey_assert(!ret);
}
void test_implicit_mprotect_exec_only_memory(int *ptr, u16 pkey)
@@ -1671,6 +1674,84 @@ void test_ptrace_modifies_pkru(int *ptr, u16 pkey)
}
#endif
+#if defined(__aarch64__)
+void test_ptrace_modifies_pkru(int *ptr, u16 pkey)
+{
+ pid_t child;
+ int status, ret;
+ struct iovec iov;
+ u64 trace_pkey;
+ /* Just a random pkey value.. */
+ u64 new_pkey = (POE_X << PKEY_BITS_PER_PKEY * 2) |
+ (POE_NONE << PKEY_BITS_PER_PKEY) |
+ POE_RWX;
+
+ child = fork();
+ pkey_assert(child >= 0);
+ dprintf3("[%d] fork() ret: %d\n", getpid(), child);
+ if (!child) {
+ ptrace(PTRACE_TRACEME, 0, 0, 0);
+
+ /* Stop and allow the tracer to modify PKRU directly */
+ raise(SIGSTOP);
+
+ /*
+ * need __read_pkey_reg() version so we do not do shadow_pkey_reg
+ * checking
+ */
+ if (__read_pkey_reg() != new_pkey)
+ exit(1);
+
+ raise(SIGSTOP);
+
+ exit(0);
+ }
+
+ pkey_assert(child == waitpid(child, &status, 0));
+ dprintf3("[%d] waitpid(%d) status: %x\n", getpid(), child, status);
+ pkey_assert(WIFSTOPPED(status) && WSTOPSIG(status) == SIGSTOP);
+
+ iov.iov_base = &trace_pkey;
+ iov.iov_len = 8;
+ ret = ptrace(PTRACE_GETREGSET, child, (void *)NT_ARM_POE, &iov);
+ pkey_assert(ret == 0);
+ pkey_assert(trace_pkey == read_pkey_reg());
+
+ trace_pkey = new_pkey;
+
+ ret = ptrace(PTRACE_SETREGSET, child, (void *)NT_ARM_POE, &iov);
+ pkey_assert(ret == 0);
+
+ /* Test that the modification is visible in ptrace before any execution */
+ memset(&trace_pkey, 0, sizeof(trace_pkey));
+ ret = ptrace(PTRACE_GETREGSET, child, (void *)NT_ARM_POE, &iov);
+ pkey_assert(ret == 0);
+ pkey_assert(trace_pkey == new_pkey);
+
+ /* Execute the tracee */
+ ret = ptrace(PTRACE_CONT, child, 0, 0);
+ pkey_assert(ret == 0);
+
+ /* Test that the tracee saw the PKRU value change */
+ pkey_assert(child == waitpid(child, &status, 0));
+ dprintf3("[%d] waitpid(%d) status: %x\n", getpid(), child, status);
+ pkey_assert(WIFSTOPPED(status) && WSTOPSIG(status) == SIGSTOP);
+
+ /* Test that the modification is visible in ptrace after execution */
+ memset(&trace_pkey, 0, sizeof(trace_pkey));
+ ret = ptrace(PTRACE_GETREGSET, child, (void *)NT_ARM_POE, &iov);
+ pkey_assert(ret == 0);
+ pkey_assert(trace_pkey == new_pkey);
+
+ ret = ptrace(PTRACE_CONT, child, 0, 0);
+ pkey_assert(ret == 0);
+ pkey_assert(child == waitpid(child, &status, 0));
+ dprintf3("[%d] waitpid(%d) status: %x\n", getpid(), child, status);
+ pkey_assert(WIFEXITED(status));
+ pkey_assert(WEXITSTATUS(status) == 0);
+}
+#endif
+
void test_mprotect_pkey_on_unsupported_cpu(int *ptr, u16 pkey)
{
int size = PAGE_SIZE;
@@ -1706,7 +1787,7 @@ void (*pkey_tests[])(int *ptr, u16 pkey) = {
test_pkey_syscalls_bad_args,
test_pkey_alloc_exhaust,
test_pkey_alloc_free_attach_pkey0,
-#if defined(__i386__) || defined(__x86_64__)
+#if defined(__i386__) || defined(__x86_64__) || defined(__aarch64__)
test_ptrace_modifies_pkru,
#endif
};
--
2.25.1
