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Commit 521c6461 authored by Mark Rutland's avatar Mark Rutland Committed by Will Deacon
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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: default avatarMark Rutland <mark.rutland@arm.com>
Fixes: 77c97b4e ("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: default avatarWill Deacon <will.deacon@arm.com>
parent 8b6e70fc

arch/arm64/kernel/cpufeature.c

+1 −1
Original line number Diff line number Diff line
@@ -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;

	}