From: James Morse Date: Fri, 24 Apr 2020 16:38:03 +0000 (+0100) Subject: arm64: Fake the IminLine size on systems affected by Neoverse-N1 #1542419 X-Git-Tag: v5.4.36~164 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=6de0c621191a42c3574d261a06a35841fc9b777a;p=platform%2Fkernel%2Flinux-rpi.git arm64: Fake the IminLine size on systems affected by Neoverse-N1 #1542419 [ 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 Reviewed-by: Suzuki K Poulose Signed-off-by: Catalin Marinas Signed-off-by: James Morse Signed-off-by: Sasha Levin --- diff --git a/arch/arm64/include/asm/cache.h b/arch/arm64/include/asm/cache.h index 43da6dd..806e9dc 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 465f0a0..4e3e9d9 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);