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arm64: cpufeature: correctly handle MRS to XZR 

In emulate_mrs() we may erroneously write back to the user SP rather
than XZR if we trap an MRS instruction where Xt == 31.

Use the new pt_regs_write_reg() helper to handle this correctly.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Fixes: 77c97b4ee2 ("arm64: cpufeature: Expose CPUID registers by emulation")
Cc: Andre Przywara <andre.przywara@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Mark Rutland 2017-02-09 15:19:20 +00:00 committed by Will Deacon
parent 8b6e70fccf
commit 521c646108
1 changed files with 1 additions and 1 deletions
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2
arch/arm64/kernel/cpufeature.c
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@ -1214,7 +1214,7 @@ static int emulate_mrs(struct pt_regs *regs, u32 insn)
rc = emulate_sys_reg(sys_reg, &val);
if (!rc) {
dst = aarch64_insn_decode_register(AARCH64_INSN_REGTYPE_RT, insn);
regs->user_regs.regs[dst] = val;
pt_regs_write_reg(regs, dst, val);
regs->pc += 4;
}