arm64: fix hyp mode mismatch detection
authorMark Rutland <mark.rutland@arm.com>
Fri, 13 Mar 2015 16:14:36 +0000 (16:14 +0000)
committerWill Deacon <will.deacon@arm.com>
Tue, 17 Mar 2015 16:58:55 +0000 (16:58 +0000)
commit424a383824faecce246691694fd5546859dac511
tree024fbd4ac78cc51bee0e73b972452f0a407ab61f
parent137650aad96c9594683445e41afa8ac5a2097520
arm64: fix hyp mode mismatch detection

Commit 828e9834e9a5b7e6 ("arm64: head: create a new function for setting
the boot_cpu_mode flag") added BOOT_CPU_MODE_EL1, a nonzero value
replacing uses of zero. However it failed to update __boot_cpu_mode
appropriately.

A CPU booted at EL2 writes BOOT_CPU_MODE_EL2 to __boot_cpu_mode[0], and
a CPU booted at EL1 writes BOOT_CPU_MODE_EL1 to __boot_cpu_mode[1].
Later is_hyp_mode_mismatched() determines there to be a mismatch if
__boot_cpu_mode[0] != __boot_cpu_mode[1].

If all CPUs are booted at EL1, __boot_cpu_mode[0] will be set to
BOOT_CPU_MODE_EL1, but __boot_cpu_mode[1] will retain its initial value
of zero, and is_hyp_mode_mismatched will erroneously determine that the
boot modes are mismatched. This hasn't been a problem so far, but later
patches which will make use of is_hyp_mode_mismatched() expect it to
work correctly.

This patch initialises __boot_cpu_mode[1] to BOOT_CPU_MODE_EL1, fixing
the erroneous mismatch detection when all CPUs are booted at EL1.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Tested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
arch/arm64/kernel/head.S