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| author | Marc Zyngier <maz@kernel.org> | 2020-07-06 17:38:02 +0100 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2020-07-08 22:07:19 +0100 |
| commit | dc802f2bc0208f4abca420705a860c5175db4bee (patch) | |
| tree | 54624c34689321f23e0d19637a891199a6cda0db /arch | |
| parent | 4b661d6133c5d3a7c9aca0b4ee5a78c7766eff3f (diff) | |
| download | linux-dc802f2bc0208f4abca420705a860c5175db4bee.tar.bz2 | |
arm64: Rework ARM_ERRATUM_1414080 handling
The current handling of erratum 1414080 has the side effect that
cntkctl_el1 can get changed for both 32 and 64bit tasks.
This isn't a problem so far, but if we ever need to mitigate another
of these errata on the 64bit side, we'd better keep the messing with
cntkctl_el1 local to 32bit tasks.
For that, make sure that on entering the kernel from a 32bit tasks,
userspace access to cntvct gets enabled, and disabled returning to
userspace, while it never gets changed for 64bit tasks.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20200706163802.1836732-5-maz@kernel.org
[will: removed branch instructions per Mark's review comments]
Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/arm64/kernel/entry.S | 34 |
1 files changed, 19 insertions, 15 deletions
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 5304d193c79d..9757a8d5fd94 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -167,6 +167,17 @@ alternative_cb_end stp x28, x29, [sp, #16 * 14] .if \el == 0 + .if \regsize == 32 + // If we're returning from a 32-bit task on a system affected by + // 1418040 then re-enable userspace access to the virtual counter. +#ifdef CONFIG_ARM64_ERRATUM_1418040 +alternative_if ARM64_WORKAROUND_1418040 + mrs x0, cntkctl_el1 + orr x0, x0, #2 // ARCH_TIMER_USR_VCT_ACCESS_EN + msr cntkctl_el1, x0 +alternative_else_nop_endif +#endif + .endif clear_gp_regs mrs x21, sp_el0 ldr_this_cpu tsk, __entry_task, x20 @@ -320,6 +331,14 @@ alternative_else_nop_endif tst x22, #PSR_MODE32_BIT // native task? b.eq 3f +#ifdef CONFIG_ARM64_ERRATUM_1418040 +alternative_if ARM64_WORKAROUND_1418040 + mrs x0, cntkctl_el1 + bic x0, x0, #2 // ARCH_TIMER_USR_VCT_ACCESS_EN + msr cntkctl_el1, x0 +alternative_else_nop_endif +#endif + #ifdef CONFIG_ARM64_ERRATUM_845719 alternative_if ARM64_WORKAROUND_845719 #ifdef CONFIG_PID_IN_CONTEXTIDR @@ -331,21 +350,6 @@ alternative_if ARM64_WORKAROUND_845719 alternative_else_nop_endif #endif 3: -#ifdef CONFIG_ARM64_ERRATUM_1418040 -alternative_if_not ARM64_WORKAROUND_1418040 - b 4f -alternative_else_nop_endif - /* - * if (x22.mode32 == cntkctl_el1.el0vcten) - * cntkctl_el1.el0vcten = ~cntkctl_el1.el0vcten - */ - mrs x1, cntkctl_el1 - eon x0, x1, x22, lsr #3 - tbz x0, #1, 4f - eor x1, x1, #2 // ARCH_TIMER_USR_VCT_ACCESS_EN - msr cntkctl_el1, x1 -4: -#endif scs_save tsk, x0 /* No kernel C function calls after this as user keys are set. */ |