[ Upstream commit ee9d90be9ddace01b7fb126567e4b539fbe1f82f ]
Systems affected by Neoverse-N1 #1542419 support DIC so do not need to
perform icache maintenance once new instructions are cleaned to the PoU.
For the errata workaround, the kernel hides DIC from user-space, so that
the unnecessary cache maintenance can be trapped by firmware.
To reduce the number of traps, produce a fake IminLine value based on
PAGE_SIZE.
Signed-off-by: James Morse <james.morse@xxxxxxx>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Signed-off-by: James Morse <james.morse@xxxxxxx>
---
arch/arm64/include/asm/cache.h | 3 ++-
arch/arm64/kernel/traps.c | 8 +++++++-
2 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/include/asm/cache.h b/arch/arm64/include/asm/cache.h
index 43da6dd29592..806e9dc2a852 100644
--- a/arch/arm64/include/asm/cache.h
+++ b/arch/arm64/include/asm/cache.h
@@ -11,6 +11,7 @@
#define CTR_L1IP_MASK 3
#define CTR_DMINLINE_SHIFT 16
#define CTR_IMINLINE_SHIFT 0
+#define CTR_IMINLINE_MASK 0xf
#define CTR_ERG_SHIFT 20
#define CTR_CWG_SHIFT 24
#define CTR_CWG_MASK 15
@@ -18,7 +19,7 @@
#define CTR_DIC_SHIFT 29
#define CTR_CACHE_MINLINE_MASK \
- (0xf << CTR_DMINLINE_SHIFT | 0xf << CTR_IMINLINE_SHIFT)
+ (0xf << CTR_DMINLINE_SHIFT | CTR_IMINLINE_MASK << CTR_IMINLINE_SHIFT)
#define CTR_L1IP(ctr) (((ctr) >> CTR_L1IP_SHIFT) & CTR_L1IP_MASK)
diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index 465f0a0f8f0a..4e3e9d9c8151 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -470,9 +470,15 @@ static void ctr_read_handler(unsigned int esr, struct pt_regs *regs)
int rt = ESR_ELx_SYS64_ISS_RT(esr);
unsigned long val = arm64_ftr_reg_user_value(&arm64_ftr_reg_ctrel0);
- if (cpus_have_const_cap(ARM64_WORKAROUND_1542419))
+ if (cpus_have_const_cap(ARM64_WORKAROUND_1542419)) {
+ /* Hide DIC so that we can trap the unnecessary maintenance...*/
val &= ~BIT(CTR_DIC_SHIFT);
+ /* ... and fake IminLine to reduce the number of traps. */
+ val &= ~CTR_IMINLINE_MASK;
+ val |= (PAGE_SHIFT - 2) & CTR_IMINLINE_MASK;
+ }
+
pt_regs_write_reg(regs, rt, val);
arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE);
--
2.19.1
