diff options
| author | Ard Biesheuvel <ard.biesheuvel@linaro.org> | 2016-03-21 18:35:11 +0100 |
|---|---|---|
| committer | Neeraj Upadhyay <neeraju@codeaurora.org> | 2017-03-22 19:22:53 +0530 |
| commit | 9fcccba399ea0d840d0f6e60ff7efccef1d7a08e (patch) | |
| tree | 359362191672e1220e15c1ff33d356f245f584b1 /arch | |
| parent | c1ef16be6d3c5606edb7a23398611d010b405aa8 (diff) | |
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
Change-Id: I6a79b0c3b2e2306d080406c7f617483f6f1519b0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Git-commit: d5e5743797adc26e09db262e7a4b6b81d8c0f45c
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
[neeraju@codeaurora.org: resolve trivial merge conflicts]
Signed-off-by: Neeraj Upadhyay <neeraju@codeaurora.org>
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 8cfd5ab37743..a1c2ac38771d 100644 --- a/arch/arm64/kernel/head.S +++ b/arch/arm64/kernel/head.S @@ -664,7 +664,7 @@ ENDPROC(__secondary_switched) */ .section ".idmap.text", "ax" ENTRY(__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 @@ -691,7 +691,7 @@ ENTRY(__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 |