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| author | Will Deacon <will@kernel.org> | 2021-07-30 13:24:41 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2021-08-20 12:33:07 +0200 |
| commit | ead7de462ae56b2d2e56fb5a414f6e916dddc4c9 (patch) | |
| tree | 6bd5c5cf36d56e92a9e81a30bfb49ec4ef37f621 | |
| parent | arm64: Advertise CPUs capable of running 32-bit applications in sysfs (diff) | |
| download | linux-ead7de462ae56b2d2e56fb5a414f6e916dddc4c9.tar.xz linux-ead7de462ae56b2d2e56fb5a414f6e916dddc4c9.zip | |
arm64: Hook up cmdline parameter to allow mismatched 32-bit EL0
Allow systems with mismatched 32-bit support at EL0 to run 32-bit
applications based on a new kernel parameter.
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20210730112443.23245-15-will@kernel.org
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 8 | ||||
| -rw-r--r-- | arch/arm64/kernel/cpufeature.c | 7 |
2 files changed, 15 insertions, 0 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index bdb22006f713..6ab625dea8c0 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -287,6 +287,14 @@ do not want to use tracing_snapshot_alloc() as it needs to be done where GFP_KERNEL allocations are allowed. + allow_mismatched_32bit_el0 [ARM64] + Allow execve() of 32-bit applications and setting of the + PER_LINUX32 personality on systems where only a strict + subset of the CPUs support 32-bit EL0. When this + parameter is present, the set of CPUs supporting 32-bit + EL0 is indicated by /sys/devices/system/cpu/aarch32_el0 + and hot-unplug operations may be restricted. + amd_iommu= [HW,X86-64] Pass parameters to the AMD IOMMU driver in the system. Possible values are: diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 0a9bc7eff26e..77b2149c26b8 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -1322,6 +1322,13 @@ const struct cpumask *system_32bit_el0_cpumask(void) return cpu_possible_mask; } +static int __init parse_32bit_el0_param(char *str) +{ + allow_mismatched_32bit_el0 = true; + return 0; +} +early_param("allow_mismatched_32bit_el0", parse_32bit_el0_param); + static ssize_t aarch32_el0_show(struct device *dev, struct device_attribute *attr, char *buf) { |