From b389d7997acb9c95331322c54ebf45a3bb97ff7b Mon Sep 17 00:00:00 2001 From: Mark Rutland Date: Mon, 9 Jan 2017 17:28:24 +0000 Subject: arm64: cpufeature: treat unknown fields as RES0 Any fields not defined in an arm64_ftr_bits entry are propagated to the system-wide register value in init_cpu_ftr_reg(), and while we require that these strictly match for the sanity checks, we don't update them in update_cpu_ftr_reg(). Generally, the lack of an arm64_ftr_bits entry indicates that the bits are currently RES0 (as is the case for the upper 32 bits of all supposedly 32-bit registers). A better default would be to use zero for the system-wide value of unallocated bits, making all register checking consistent, and allowing for subsequent simplifications to the arm64_ftr_bits arrays. This patch updates init_cpu_ftr_reg() to treat unallocated bits as RES0 for the purpose of the system-wide safe value. These bits will still be sanity checked with strict match requirements, as is currently the case. Signed-off-by: Mark Rutland Cc: Catalin Marinas Cc: Will Deacon Reviewed-by: Suzuki K Poulose Reviewed-by: Catalin Marinas Signed-off-by: Suzuki K Poulose Signed-off-by: Will Deacon --- arch/arm64/kernel/cpufeature.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) (limited to 'arch/arm64/kernel/cpufeature.c') diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index e8f6dfba1973..9cc198e81613 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -415,23 +415,33 @@ static void __init sort_ftr_regs(void) /* * Initialise the CPU feature register from Boot CPU values. * Also initiliases the strict_mask for the register. + * Any bits that are not covered by an arm64_ftr_bits entry are considered + * RES0 for the system-wide value, and must strictly match. */ static void __init init_cpu_ftr_reg(u32 sys_reg, u64 new) { u64 val = 0; u64 strict_mask = ~0x0ULL; + u64 valid_mask = 0; + const struct arm64_ftr_bits *ftrp; struct arm64_ftr_reg *reg = get_arm64_ftr_reg(sys_reg); BUG_ON(!reg); for (ftrp = reg->ftr_bits; ftrp->width; ftrp++) { + u64 ftr_mask = arm64_ftr_mask(ftrp); s64 ftr_new = arm64_ftr_value(ftrp, new); val = arm64_ftr_set_value(ftrp, val, ftr_new); + + valid_mask |= ftr_mask; if (!ftrp->strict) - strict_mask &= ~arm64_ftr_mask(ftrp); + strict_mask &= ~ftr_mask; } + + val &= valid_mask; + reg->sys_val = val; reg->strict_mask = strict_mask; } -- cgit v1.2.3