[PATCH v18 13/24] selftests/vm/pkeys: Introduce powerpc support

Sandipan Das
2020-01-30T06:37:56Z

This makes use of the abstractions added earlier and
introduces support for powerpc.

For powerpc, after receiving the SIGSEGV, the signal
handler must explicitly restore access permissions
for the faulting pkey to allow the test to continue.
As this makes use of pkey_access_allow(), all of its
dependencies and other similar functions have been
moved ahead of the signal handler.

cc: Dave Hansen <dave.hansen@intel.com>
cc: Florian Weimer <fweimer@redhat.com>
Signed-off-by: Ram Pai <linuxram@us.ibm.com>
Signed-off-by: Sandipan Das <sandipan@linux.ibm.com>
---
tools/testing/selftests/vm/pkey-helpers.h | 2 +
tools/testing/selftests/vm/pkey-powerpc.h | 90 +++++++
tools/testing/selftests/vm/protection_keys.c | 269 ++++++++++---------
3 files changed, 233 insertions(+), 128 deletions(-)
create mode 100644 tools/testing/selftests/vm/pkey-powerpc.h

diff --git a/tools/testing/selftests/vm/pkey-helpers.h b/tools/testing/selftests/vm/pkey-helpers.h
index 621fb2a0a5ef..2f4b1eb3a680 100644
--- a/tools/testing/selftests/vm/pkey-helpers.h
+++ b/tools/testing/selftests/vm/pkey-helpers.h
@@ -79,6 +79,8 @@ void expected_pkey_fault(int pkey);

#if defined(__i386__) || defined(__x86_64__) /* arch */
#include "pkey-x86.h"
+#elif defined(__powerpc64__) /* arch */
+#include "pkey-powerpc.h"
#else /* arch */
#error Architecture not supported
#endif /* arch */
diff --git a/tools/testing/selftests/vm/pkey-powerpc.h b/tools/testing/selftests/vm/pkey-powerpc.h
new file mode 100644
index 000000000000..c79f4160a6a0
--- /dev/null
+++ b/tools/testing/selftests/vm/pkey-powerpc.h
@@ -0,0 +1,90 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef _PKEYS_POWERPC_H
+#define _PKEYS_POWERPC_H
+
+#ifndef SYS_mprotect_key
+# define SYS_mprotect_key 386
+#endif
+#ifndef SYS_pkey_alloc
+# define SYS_pkey_alloc 384
+# define SYS_pkey_free 385
+#endif
+#define REG_IP_IDX PT_NIP
+#define REG_TRAPNO PT_TRAP
+#define gregs gp_regs
+#define fpregs fp_regs
+#define si_pkey_offset 0x20
+
+#ifndef PKEY_DISABLE_ACCESS
+# define PKEY_DISABLE_ACCESS 0x3 /* disable read and write */
+#endif
+
+#ifndef PKEY_DISABLE_WRITE
+# define PKEY_DISABLE_WRITE 0x2
+#endif
+
+#define NR_PKEYS 32
+#define NR_RESERVED_PKEYS_4K 27 /* pkey-0, pkey-1, exec-only-pkey
+ and 24 other keys that cannot be
+ represented in the PTE */
+#define NR_RESERVED_PKEYS_64K 3 /* pkey-0, pkey-1 and exec-only-pkey */
+#define PKEY_BITS_PER_PKEY 2
+#define HPAGE_SIZE (1UL << 24)
+#define PAGE_SIZE (1UL << 16)
+
+static inline u32 pkey_bit_position(int pkey)
+{
+ return (NR_PKEYS - pkey - 1) * PKEY_BITS_PER_PKEY;
+}
+
+static inline u64 __read_pkey_reg(void)
+{
+ u64 pkey_reg;
+
+ asm volatile("mfspr %0, 0xd" : "=r" (pkey_reg));
+
+ return pkey_reg;
+}
+
+static inline void __write_pkey_reg(u64 pkey_reg)
+{
+ u64 amr = pkey_reg;
+
+ dprintf4("%s() changing %016llx to %016llx\n",
+ __func__, __read_pkey_reg(), pkey_reg);
+
+ asm volatile("mtspr 0xd, %0" : : "r" ((unsigned long)(amr)) : "memory");
+
+ dprintf4("%s() pkey register after changing %016llx to %016llx\n",
+ __func__, __read_pkey_reg(), pkey_reg);
+}
+
+static inline int cpu_has_pku(void)
+{
+ return 1;
+}
+
+static inline int get_arch_reserved_keys(void)
+{
+ if (sysconf(_SC_PAGESIZE) == 4096)
+ return NR_RESERVED_PKEYS_4K;
+ else
+ return NR_RESERVED_PKEYS_64K;
+}
+
+void expect_fault_on_read_execonly_key(void *p1, int pkey)
+{
+ /*
+ * powerpc does not allow userspace to change permissions of exec-only
+ * keys since those keys are not allocated by userspace. The signal
+ * handler wont be able to reset the permissions, which means the code
+ * will infinitely continue to segfault here.
+ */
+ return;
+}
+
+/* 4-byte instructions * 16384 = 64K page */
+#define __page_o_noops() asm(".rept 16384 ; nop; .endr")
+
+#endif /* _PKEYS_POWERPC_H */
diff --git a/tools/testing/selftests/vm/protection_keys.c b/tools/testing/selftests/vm/protection_keys.c
index 57c71056c93d..e6de078a9196 100644
--- a/tools/testing/selftests/vm/protection_keys.c
+++ b/tools/testing/selftests/vm/protection_keys.c
@@ -169,6 +169,125 @@ void dump_mem(void *dumpme, int len_bytes)
}
}

+static u32 hw_pkey_get(int pkey, unsigned long flags)
+{
+ u64 pkey_reg = __read_pkey_reg();
+
+ dprintf1("%s(pkey=%d, flags=%lx) = %x / %d\n",
+ __func__, pkey, flags, 0, 0);
+ dprintf2("%s() raw pkey_reg: %016llx\n", __func__, pkey_reg);
+
+ return (u32) get_pkey_bits(pkey_reg, pkey);
+}
+
+static int hw_pkey_set(int pkey, unsigned long rights, unsigned long flags)
+{
+ u32 mask = (PKEY_DISABLE_ACCESS|PKEY_DISABLE_WRITE);
+ u64 old_pkey_reg = __read_pkey_reg();
+ u64 new_pkey_reg;
+
+ /* make sure that 'rights' only contains the bits we expect: */
+ assert(!(rights & ~mask));
+
+ /* modify bits accordingly in old pkey_reg and assign it */
+ new_pkey_reg = set_pkey_bits(old_pkey_reg, pkey, rights);
+
+ __write_pkey_reg(new_pkey_reg);
+
+ dprintf3("%s(pkey=%d, rights=%lx, flags=%lx) = %x"
+ " pkey_reg now: %016llx old_pkey_reg: %016llx\n",
+ __func__, pkey, rights, flags, 0, __read_pkey_reg(),
+ old_pkey_reg);
+ return 0;
+}
+
+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);
+ pkey_assert(flags & (PKEY_DISABLE_ACCESS | PKEY_DISABLE_WRITE));
+
+ pkey_rights = hw_pkey_get(pkey, syscall_flags);
+
+ dprintf1("%s(%d) hw_pkey_get(%d): %x\n", __func__,
+ pkey, pkey, pkey_rights);
+
+ pkey_assert(pkey_rights >= 0);
+
+ pkey_rights |= flags;
+
+ ret = hw_pkey_set(pkey, pkey_rights, syscall_flags);
+ assert(!ret);
+ /* pkey_reg and flags have the same format */
+ shadow_pkey_reg = set_pkey_bits(shadow_pkey_reg, pkey, pkey_rights);
+ dprintf1("%s(%d) shadow: 0x%016llx\n",
+ __func__, pkey, shadow_pkey_reg);
+
+ pkey_assert(ret >= 0);
+
+ pkey_rights = hw_pkey_get(pkey, syscall_flags);
+ dprintf1("%s(%d) hw_pkey_get(%d): %x\n", __func__,
+ pkey, pkey, pkey_rights);
+
+ 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);
+}
+
+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));
+
+ dprintf1("%s(%d) hw_pkey_get(%d): %x\n", __func__,
+ pkey, pkey, pkey_rights);
+ pkey_assert(pkey_rights >= 0);
+
+ pkey_rights &= ~flags;
+
+ ret = hw_pkey_set(pkey, pkey_rights, 0);
+ shadow_pkey_reg = set_pkey_bits(shadow_pkey_reg, pkey, pkey_rights);
+ pkey_assert(ret >= 0);
+
+ pkey_rights = hw_pkey_get(pkey, syscall_flags);
+ dprintf1("%s(%d) hw_pkey_get(%d): %x\n", __func__,
+ pkey, pkey, pkey_rights);
+
+ 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)
+{
+ pkey_disable_clear(pkey, PKEY_DISABLE_WRITE);
+}
+void pkey_write_deny(int pkey)
+{
+ pkey_disable_set(pkey, PKEY_DISABLE_WRITE);
+}
+void pkey_access_allow(int pkey)
+{
+ pkey_disable_clear(pkey, PKEY_DISABLE_ACCESS);
+}
+void pkey_access_deny(int pkey)
+{
+ pkey_disable_set(pkey, PKEY_DISABLE_ACCESS);
+}
+
/* Failed address bound checks: */
#ifndef SEGV_BNDERR
# define SEGV_BNDERR 3
@@ -199,11 +318,12 @@ void signal_handler(int signum, siginfo_t *si, void *vucontext)
int trapno;
unsigned long ip;
char *fpregs;
+#if defined(__i386__) || defined(__x86_64__) /* arch */
u32 *pkey_reg_ptr;
+ int pkey_reg_offset;
+#endif /* arch */
u64 siginfo_pkey;
u32 *si_pkey_ptr;
- int pkey_reg_offset;
- fpregset_t fpregset;

dprint_in_signal = 1;
dprintf1(">>>>===============SIGSEGV============================\n");
@@ -213,12 +333,13 @@ void signal_handler(int signum, siginfo_t *si, void *vucontext)

trapno = uctxt->uc_mcontext.gregs[REG_TRAPNO];
ip = uctxt->uc_mcontext.gregs[REG_IP_IDX];
- fpregset = uctxt->uc_mcontext.fpregs;
- fpregs = (void *)fpregset;
+ fpregs = (char *) uctxt->uc_mcontext.fpregs;

dprintf2("%s() trapno: %d ip: 0x%016lx info->si_code: %s/%d\n",
__func__, trapno, ip, si_code_str(si->si_code),
si->si_code);
+
+#if defined(__i386__) || defined(__x86_64__) /* arch */
#ifdef __i386__
/*
* 32-bit has some extra padding so that userspace can tell whether
@@ -226,12 +347,10 @@ void signal_handler(int signum, siginfo_t *si, void *vucontext)
* state. We just assume that it is here.
*/
fpregs += 0x70;
-#endif
+#endif /* i386 */
pkey_reg_offset = pkey_reg_xstate_offset();
pkey_reg_ptr = (void *)(&fpregs[pkey_reg_offset]);

- dprintf1("siginfo: %p\n", si);
- dprintf1(" fpregs: %p\n", fpregs);
/*
* If we got a PKEY fault, we *HAVE* to have at least one bit set in
* here.
@@ -240,6 +359,10 @@ void signal_handler(int signum, siginfo_t *si, void *vucontext)
if (DEBUG_LEVEL > 4)
dump_mem(pkey_reg_ptr - 128, 256);
pkey_assert(*pkey_reg_ptr);
+#endif /* arch */
+
+ dprintf1("siginfo: %p\n", si);
+ dprintf1(" fpregs: %p\n", fpregs);

if ((si->si_code == SEGV_MAPERR) ||
(si->si_code == SEGV_ACCERR) ||
@@ -248,14 +371,13 @@ void signal_handler(int signum, siginfo_t *si, void *vucontext)
exit(4);
}

- si_pkey_ptr = (u32 *)(((u8 *)si) + si_pkey_offset);
+ si_pkey_ptr = siginfo_get_pkey_ptr(si);
dprintf1("si_pkey_ptr: %p\n", si_pkey_ptr);
dump_mem((u8 *)si_pkey_ptr - 8, 24);
siginfo_pkey = *si_pkey_ptr;
pkey_assert(siginfo_pkey < NR_PKEYS);
last_si_pkey = siginfo_pkey;

- dprintf1("signal pkey_reg from xsave: %08x\n", *pkey_reg_ptr);
/*
* need __read_pkey_reg() version so we do not do shadow_pkey_reg
* checking
@@ -263,8 +385,14 @@ void signal_handler(int signum, siginfo_t *si, void *vucontext)
dprintf1("signal pkey_reg from pkey_reg: %016llx\n",
__read_pkey_reg());
dprintf1("pkey from siginfo: %016llx\n", siginfo_pkey);
+#if defined(__i386__) || defined(__x86_64__) /* arch */
+ dprintf1("signal pkey_reg from xsave: %08x\n", *pkey_reg_ptr);
*(u64 *)pkey_reg_ptr = 0x00000000;
dprintf1("WARNING: set PKEY_REG=0 to allow faulting instruction to continue\n");
+#elif defined(__powerpc64__) /* arch */
+ /* restore access and let the faulting instruction continue */
+ pkey_access_allow(siginfo_pkey);
+#endif /* arch */
pkey_faults++;
dprintf1("<<<<==================================================\n");
dprint_in_signal = 0;
@@ -333,125 +461,6 @@ pid_t fork_lazy_child(void)
return forkret;
}

-static u32 hw_pkey_get(int pkey, unsigned long flags)
-{
- u64 pkey_reg = __read_pkey_reg();
-
- dprintf1("%s(pkey=%d, flags=%lx) = %x / %d\n",
- __func__, pkey, flags, 0, 0);
- dprintf2("%s() raw pkey_reg: %016llx\n", __func__, pkey_reg);
-
- return (u32) get_pkey_bits(pkey_reg, pkey);
-}
-
-static int hw_pkey_set(int pkey, unsigned long rights, unsigned long flags)
-{
- u32 mask = (PKEY_DISABLE_ACCESS|PKEY_DISABLE_WRITE);
- u64 old_pkey_reg = __read_pkey_reg();
- u64 new_pkey_reg;
-
- /* make sure that 'rights' only contains the bits we expect: */
- assert(!(rights & ~mask));
-
- /* modify bits accordingly in old pkey_reg and assign it */
- new_pkey_reg = set_pkey_bits(old_pkey_reg, pkey, rights);
-
- __write_pkey_reg(new_pkey_reg);
-
- dprintf3("%s(pkey=%d, rights=%lx, flags=%lx) = %x"
- " pkey_reg now: %016llx old_pkey_reg: %016llx\n",
- __func__, pkey, rights, flags, 0, __read_pkey_reg(),
- old_pkey_reg);
- return 0;
-}
-
-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);
- pkey_assert(flags & (PKEY_DISABLE_ACCESS | PKEY_DISABLE_WRITE));
-
- pkey_rights = hw_pkey_get(pkey, syscall_flags);
-
- dprintf1("%s(%d) hw_pkey_get(%d): %x\n", __func__,
- pkey, pkey, pkey_rights);
-
- pkey_assert(pkey_rights >= 0);
-
- pkey_rights |= flags;
-
- ret = hw_pkey_set(pkey, pkey_rights, syscall_flags);
- assert(!ret);
- /* pkey_reg and flags have the same format */
- shadow_pkey_reg = set_pkey_bits(shadow_pkey_reg, pkey, pkey_rights);
- dprintf1("%s(%d) shadow: 0x%016llx\n",
- __func__, pkey, shadow_pkey_reg);
-
- pkey_assert(ret >= 0);
-
- pkey_rights = hw_pkey_get(pkey, syscall_flags);
- dprintf1("%s(%d) hw_pkey_get(%d): %x\n", __func__,
- pkey, pkey, pkey_rights);
-
- 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);
-}
-
-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));
-
- dprintf1("%s(%d) hw_pkey_get(%d): %x\n", __func__,
- pkey, pkey, pkey_rights);
- pkey_assert(pkey_rights >= 0);
-
- pkey_rights &= ~flags;
-
- ret = hw_pkey_set(pkey, pkey_rights, 0);
- shadow_pkey_reg = set_pkey_bits(shadow_pkey_reg, pkey, pkey_rights);
- pkey_assert(ret >= 0);
-
- pkey_rights = hw_pkey_get(pkey, syscall_flags);
- dprintf1("%s(%d) hw_pkey_get(%d): %x\n", __func__,
- pkey, pkey, pkey_rights);
-
- 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)
-{
- pkey_disable_clear(pkey, PKEY_DISABLE_WRITE);
-}
-void pkey_write_deny(int pkey)
-{
- pkey_disable_set(pkey, PKEY_DISABLE_WRITE);
-}
-void pkey_access_allow(int pkey)
-{
- pkey_disable_clear(pkey, PKEY_DISABLE_ACCESS);
-}
-void pkey_access_deny(int pkey)
-{
- pkey_disable_set(pkey, PKEY_DISABLE_ACCESS);
-}
-
int sys_mprotect_pkey(void *ptr, size_t size, unsigned long orig_prot,
unsigned long pkey)
{
@@ -890,11 +899,15 @@ void expected_pkey_fault(int pkey)
if (pkey != UNKNOWN_PKEY)
pkey_assert(last_si_pkey == pkey);

+#if defined(__i386__) || defined(__x86_64__) /* arch */
/*
* The signal handler shold have cleared out PKEY register to let the
* test program continue. We now have to restore it.
*/
if (__read_pkey_reg() != 0)
+#else /* arch */
+ if (__read_pkey_reg() != shadow_pkey_reg)
+#endif /* arch */
pkey_assert(0);

__write_pkey_reg(shadow_pkey_reg);
--
2.17.1