The hypervisor interface has defined branch prediction security bits for
handling the link stack. Wire them up.
Signed-off-by: Nicholas Piggin <npig...@gmail.com>
---
arch/powerpc/include/asm/hvcall.h | 2 ++
arch/powerpc/platforms/pseries/setup.c | 6 ++++++
2 files changed, 8 insertions(+)
diff --git a/arch/powerpc/include/asm/hvcall.h
b/arch/powerpc/include/asm/hvcall.h
index fbb377055471..e66627fc1972 100644
--- a/arch/powerpc/include/asm/hvcall.h
+++ b/arch/powerpc/include/asm/hvcall.h
@@ -375,11 +375,13 @@
#define H_CPU_CHAR_THREAD_RECONFIG_CTRL (1ull << 57) // IBM bit 6
#define H_CPU_CHAR_COUNT_CACHE_DISABLED (1ull << 56) // IBM bit 7
#define H_CPU_CHAR_BCCTR_FLUSH_ASSIST (1ull << 54) // IBM bit 9
+#define H_CPU_CHAR_BCCTR_LINK_FLUSH_ASSIST (1ull << 52) // IBM bit 11
#define H_CPU_BEHAV_FAVOUR_SECURITY (1ull << 63) // IBM bit 0
#define H_CPU_BEHAV_L1D_FLUSH_PR (1ull << 62) // IBM bit 1
#define H_CPU_BEHAV_BNDS_CHK_SPEC_BAR (1ull << 61) // IBM bit 2
#define H_CPU_BEHAV_FLUSH_COUNT_CACHE (1ull << 58) // IBM bit 5
+#define H_CPU_BEHAV_FLUSH_LINK_STACK (1ull << 57) // IBM bit 6
/* Flag values used in H_REGISTER_PROC_TBL hcall */
#define PROC_TABLE_OP_MASK 0x18
diff --git a/arch/powerpc/platforms/pseries/setup.c
b/arch/powerpc/platforms/pseries/setup.c
index 2f4ee0a90284..633c45ec406d 100644
--- a/arch/powerpc/platforms/pseries/setup.c
+++ b/arch/powerpc/platforms/pseries/setup.c
@@ -519,9 +519,15 @@ static void init_cpu_char_feature_flags(struct
h_cpu_char_result *result)
if (result->character & H_CPU_CHAR_BCCTR_FLUSH_ASSIST)
security_ftr_set(SEC_FTR_BCCTR_FLUSH_ASSIST);
+ if (result->character & H_CPU_CHAR_BCCTR_LINK_FLUSH_ASSIST)
+ security_ftr_set(SEC_FTR_BCCTR_LINK_FLUSH_ASSIST);
+
if (result->behaviour & H_CPU_BEHAV_FLUSH_COUNT_CACHE)
security_ftr_set(SEC_FTR_FLUSH_COUNT_CACHE);
+ if (result->behaviour & H_CPU_BEHAV_FLUSH_LINK_STACK)
+ security_ftr_set(SEC_FTR_FLUSH_LINK_STACK);
+
/*
* The features below are enabled by default, so we instead look to see
* if firmware has *disabled* them, and clear them if so.
--
2.23.0
