diff options
| author | Will Deacon <will.deacon@arm.com> | 2018-08-07 14:47:06 +0200 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2018-09-14 18:46:19 +0200 |
| commit | 8f04e8e6e29c93421a95b61cad62e3918425eac7 (patch) | |
| tree | d933a8bd5c9e9a3094019c9bc51d5b5178eb768e /arch/arm64/kernel/ssbd.c | |
| parent | arm64: entry: Allow handling of undefined instructions from EL1 (diff) | |
| download | linux-8f04e8e6e29c93421a95b61cad62e3918425eac7.tar.xz linux-8f04e8e6e29c93421a95b61cad62e3918425eac7.zip | |
arm64: ssbd: Add support for PSTATE.SSBS rather than trapping to EL3
On CPUs with support for PSTATE.SSBS, the kernel can toggle the SSBD
state without needing to call into firmware.
This patch hooks into the existing SSBD infrastructure so that SSBS is
used on CPUs that support it, but it's all made horribly complicated by
the very real possibility of big/little systems that don't uniformly
provide the new capability.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/kernel/ssbd.c')
| -rw-r--r-- | arch/arm64/kernel/ssbd.c | 21 |
1 files changed, 21 insertions, 0 deletions
diff --git a/arch/arm64/kernel/ssbd.c b/arch/arm64/kernel/ssbd.c index 07b12c034ec2..885f13e58708 100644 --- a/arch/arm64/kernel/ssbd.c +++ b/arch/arm64/kernel/ssbd.c @@ -3,12 +3,30 @@ * Copyright (C) 2018 ARM Ltd, All Rights Reserved. */ +#include <linux/compat.h> #include <linux/errno.h> #include <linux/sched.h> +#include <linux/sched/task_stack.h> #include <linux/thread_info.h> #include <asm/cpufeature.h> +static void ssbd_ssbs_enable(struct task_struct *task) +{ + u64 val = is_compat_thread(task_thread_info(task)) ? + PSR_AA32_SSBS_BIT : PSR_SSBS_BIT; + + task_pt_regs(task)->pstate |= val; +} + +static void ssbd_ssbs_disable(struct task_struct *task) +{ + u64 val = is_compat_thread(task_thread_info(task)) ? + PSR_AA32_SSBS_BIT : PSR_SSBS_BIT; + + task_pt_regs(task)->pstate &= ~val; +} + /* * prctl interface for SSBD */ @@ -44,12 +62,14 @@ static int ssbd_prctl_set(struct task_struct *task, unsigned long ctrl) return -EPERM; task_clear_spec_ssb_disable(task); clear_tsk_thread_flag(task, TIF_SSBD); + ssbd_ssbs_enable(task); break; case PR_SPEC_DISABLE: if (state == ARM64_SSBD_FORCE_DISABLE) return -EPERM; task_set_spec_ssb_disable(task); set_tsk_thread_flag(task, TIF_SSBD); + ssbd_ssbs_disable(task); break; case PR_SPEC_FORCE_DISABLE: if (state == ARM64_SSBD_FORCE_DISABLE) @@ -57,6 +77,7 @@ static int ssbd_prctl_set(struct task_struct *task, unsigned long ctrl) task_set_spec_ssb_disable(task); task_set_spec_ssb_force_disable(task); set_tsk_thread_flag(task, TIF_SSBD); + ssbd_ssbs_disable(task); break; default: return -ERANGE; |