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arm64: Fake the IminLine size on systems affected by Neoverse-N1 #1542419 

[ Upstream commit ee9d90be9d ]

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@arm.com>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
5.4-rM2-2.2.x-imx-squashed
James Morse 2020-04-24 17:38:03 +01:00 committed by Greg Kroah-Hartman
parent f2791551ce
commit 6de0c62119
2 changed files with 9 additions and 2 deletions
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3
arch/arm64/include/asm/cache.h
View File

@ -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)

8
arch/arm64/kernel/traps.c
View File

@ -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);