The Power ISA mandates that all writes to the Authority
Mask Register (AMR) must always be preceded as well as
succeeded by a context synchronizing instruction.
This makes sure that the tests follow this requirement
when attempting to update a pkey's access rights.
Signed-off-by: Sandipan Das <sandipan@xxxxxxxxxxxxx>
---
tools/testing/selftests/powerpc/include/reg.h | 6 ++++++
tools/testing/selftests/powerpc/ptrace/core-pkey.c | 2 +-
tools/testing/selftests/powerpc/ptrace/ptrace-pkey.c | 2 +-
3 files changed, 8 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/powerpc/include/reg.h b/tools/testing/selftests/powerpc/include/reg.h
index 022c5076b2c5..c0f2742a3a59 100644
--- a/tools/testing/selftests/powerpc/include/reg.h
+++ b/tools/testing/selftests/powerpc/include/reg.h
@@ -57,6 +57,12 @@
#define SPRN_PPR 896 /* Program Priority Register */
#define SPRN_AMR 13 /* Authority Mask Register - problem state */
+#define set_amr(v) asm volatile("isync;" \
+ "mtspr " __stringify(SPRN_AMR) ",%0;" \
+ "isync" : \
+ : "r" ((unsigned long)(v)) \
+ : "memory")
+
/* TEXASR register bits */
#define TEXASR_FC 0xFE00000000000000
#define TEXASR_FP 0x0100000000000000
diff --git a/tools/testing/selftests/powerpc/ptrace/core-pkey.c b/tools/testing/selftests/powerpc/ptrace/core-pkey.c
index d5c64fee032d..bbc05ffc5860 100644
--- a/tools/testing/selftests/powerpc/ptrace/core-pkey.c
+++ b/tools/testing/selftests/powerpc/ptrace/core-pkey.c
@@ -150,7 +150,7 @@ static int child(struct shared_info *info)
printf("%-30s AMR: %016lx pkey1: %d pkey2: %d pkey3: %d\n",
user_write, info->amr, pkey1, pkey2, pkey3);
- mtspr(SPRN_AMR, info->amr);
+ set_amr(info->amr);
/*
* We won't use pkey3. This tests whether the kernel restores the UAMOR
diff --git a/tools/testing/selftests/powerpc/ptrace/ptrace-pkey.c b/tools/testing/selftests/powerpc/ptrace/ptrace-pkey.c
index bdbbbe8431e0..904c04f8c919 100644
--- a/tools/testing/selftests/powerpc/ptrace/ptrace-pkey.c
+++ b/tools/testing/selftests/powerpc/ptrace/ptrace-pkey.c
@@ -126,7 +126,7 @@ static int child(struct shared_info *info)
printf("%-30s AMR: %016lx pkey1: %d pkey2: %d pkey3: %d\n",
user_write, info->amr1, pkey1, pkey2, pkey3);
- mtspr(SPRN_AMR, info->amr1);
+ set_amr(info->amr1);
/* Wait for parent to read our AMR value and write a new one. */
ret = prod_parent(&info->child_sync);
--
2.25.1
