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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/mm | |
| parent | deeaac5175a577cbbe1a2319903781d0a7ef7720 (diff) | |
| download | linux-6982934e19f8ebb4152ba77308facdb1a38533f9.tar.bz2 | |
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/mm')
| -rw-r--r-- | arch/arm64/mm/proc.S | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S index ea0db1744c29..4cf19a26af2d 100644 --- a/arch/arm64/mm/proc.S +++ b/arch/arm64/mm/proc.S @@ -16,6 +16,7 @@ #include <asm/pgtable-hwdef.h> #include <asm/cpufeature.h> #include <asm/alternative.h> +#include <asm/smp.h> #ifdef CONFIG_ARM64_64K_PAGES #define TCR_TG_FLAGS TCR_TG0_64K | TCR_TG1_64K @@ -468,9 +469,39 @@ SYM_FUNC_START(__cpu_setup) 1: #endif /* CONFIG_ARM64_HW_AFDBM */ msr tcr_el1, x10 + mov x1, x0 /* * Prepare SCTLR */ mov_q x0, SCTLR_EL1_SET + +#ifdef CONFIG_ARM64_PTR_AUTH + /* No ptrauth setup for run time cpus */ + cmp x1, #ARM64_CPU_RUNTIME + b.eq 3f + + /* Check if the CPU supports ptrauth */ + mrs x2, id_aa64isar1_el1 + ubfx x2, x2, #ID_AA64ISAR1_APA_SHIFT, #8 + cbz x2, 3f + + msr_s SYS_APIAKEYLO_EL1, xzr + msr_s SYS_APIAKEYHI_EL1, xzr + + /* Just enable ptrauth for primary cpu */ + cmp x1, #ARM64_CPU_BOOT_PRIMARY + b.eq 2f + + /* if !system_supports_address_auth() then skip enable */ +alternative_if_not ARM64_HAS_ADDRESS_AUTH + b 3f +alternative_else_nop_endif + +2: /* Enable ptrauth instructions */ + ldr x2, =SCTLR_ELx_ENIA | SCTLR_ELx_ENIB | \ + SCTLR_ELx_ENDA | SCTLR_ELx_ENDB + orr x0, x0, x2 +3: +#endif ret // return to head.S SYM_FUNC_END(__cpu_setup) |