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| author |   Kristina Martsenko <kristina.martsenko@arm.com> | 2020-03-13 14:34:55 +0530 |
|---|---|---|
| committer |   Catalin Marinas <catalin.marinas@arm.com> | 2020-03-18 09:50:19 +0000 |
| commit | 6982934e19f8ebb4152ba77308facdb1a38533f9 (patch) | |
| tree | 97eef768ce56fab990ff5627f385e140bfded8a8 /arch/arm64/Kconfig | |
| parent | arm64: cpufeature: handle conflicts based on capability (diff) | |
| download | wireguard-linux-6982934e19f8ebb4152ba77308facdb1a38533f9.tar.xz wireguard-linux-6982934e19f8ebb4152ba77308facdb1a38533f9.zip | |
arm64: enable ptrauth earlier
When the kernel is compiled with pointer auth instructions, the boot CPU
needs to start using address auth very early, so change the cpucap to
account for this.
Pointer auth must be enabled before we call C functions, because it is
not possible to enter a function with pointer auth disabled and exit it
with pointer auth enabled. Note, mismatches between architected and
IMPDEF algorithms will still be caught by the cpufeature framework (the
separate *_ARCH and *_IMP_DEF cpucaps).
Note the change in behavior: if the boot CPU has address auth and a
late CPU does not, then the late CPU is parked by the cpufeature
framework. This is possible as kernel will only have NOP space intructions
for PAC so such mismatched late cpu will silently ignore those
instructions in C functions. Also, if the boot CPU does not have address
auth and the late CPU has then the late cpu will still boot but with
ptrauth feature disabled.
Leave generic authentication as a "system scope" cpucap for now, since
initially the kernel will only use address authentication.
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Reviewed-by: Vincenzo Frascino <Vincenzo.Frascino@arm.com>
Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
[Amit: Re-worked ptrauth setup logic, comments]
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/Kconfig')
| -rw-r--r-- | arch/arm64/Kconfig | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 0b30e884e088..87e2cbb76930 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -1515,6 +1515,12 @@ config ARM64_PTR_AUTH be enabled. However, KVM guest also require VHE mode and hence CONFIG_ARM64_VHE=y option to use this feature. + If the feature is present on the boot CPU but not on a late CPU, then + the late CPU will be parked. Also, if the boot CPU does not have + address auth and the late CPU has then the late CPU will still boot + but with the feature disabled. On such a system, this option should + not be selected. + endmenu menu "ARMv8.5 architectural features" |