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FROMLIST: arm64: Hook up cmdline parameter to allow mismatched 32-bit EL0

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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>
Bug: 178507149
Link: https://lore.kernel.org/linux-arch/20201208132835.6151-15-will@kernel.org/
Signed-off-by: Will Deacon <willdeacon@google.com>
Change-Id: I20c886efdb40c4d5abcf82c2c35a380fc10ae609
This commit is contained in:
Will Deacon
2020-10-27 21:01:52 +00:00
committed by Will Deacon
parent e0c1be11f3
commit 7896d24144
2 changed files with 15 additions and 0 deletions
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8
Documentation/admin-guide/kernel-parameters.txt
View File

@@ -289,6 +289,14 @@
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:

7
arch/arm64/kernel/cpufeature.c
View File

@@ -1293,6 +1293,13 @@ 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)
{