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| author |   Ard Biesheuvel <ard.biesheuvel@linaro.org> | 2016-03-21 18:35:11 +0100 |
|---|---|---|
| committer |   Catalin Marinas <catalin.marinas@arm.com> | 2016-03-24 16:19:24 +0000 |
| commit | d5e5743797adc26e09db262e7a4b6b81d8c0f45c (patch) | |
| tree | 3fc356370af64a6e2dd81e84bd70dca2f0a62701 /arch | |
| parent | arm64: Split pr_notice("Virtual kernel memory layout...") into multiple pr_cont() (diff) | |
| download | linux-dev-d5e5743797adc26e09db262e7a4b6b81d8c0f45c.tar.xz linux-dev-d5e5743797adc26e09db262e7a4b6b81d8c0f45c.zip | |
arm64: kaslr: use callee saved register to preserve SCTLR across C call
The KASLR code incorrectly expects the contents of x18 to be preserved
across a call into C code, and uses it to stash the contents of SCTLR_EL1
before enabling the MMU. If the MMU needs to be disabled again to create
the randomized kernel mapping, x18 is written back to SCTLR_EL1, which is
likely to crash the system if x18 has been clobbered by kasan_early_init()
or kaslr_early_init(). So use x22 instead, which is not in use so far in
head.S
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/arm64/kernel/head.S | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S index 1672ca9e963b..a2cf0e3aa1ce 100644 --- a/arch/arm64/kernel/head.S +++ b/arch/arm64/kernel/head.S @@ -732,7 +732,7 @@ ENTRY(__early_cpu_boot_status) */ .section ".idmap.text", "ax" __enable_mmu: - mrs x18, sctlr_el1 // preserve old SCTLR_EL1 value + mrs x22, sctlr_el1 // preserve old SCTLR_EL1 value mrs x1, ID_AA64MMFR0_EL1 ubfx x2, x1, #ID_AA64MMFR0_TGRAN_SHIFT, 4 cmp x2, #ID_AA64MMFR0_TGRAN_SUPPORTED @@ -760,7 +760,7 @@ __enable_mmu: * to take into account by discarding the current kernel mapping and * creating a new one. */ - msr sctlr_el1, x18 // disable the MMU + msr sctlr_el1, x22 // disable the MMU isb bl __create_page_tables // recreate kernel mapping |