arm64: Move handling of erratum 1418040
into C code
[ Upstream commit5.4-rM2-2.2.x-imx-squashedd49f7d7376
] Instead of dealing with erratum1418040
on each entry and exit, let's move the handling to __switch_to() instead, which has several advantages: - It can be applied when it matters (switching between 32 and 64 bit tasks). - It is written in C (yay!) - It can rely on static keys rather than alternatives Signed-off-by: Marc Zyngier <maz@kernel.org> Tested-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org> Reviewed-by: Stephen Boyd <swboyd@chromium.org> Acked-by: Will Deacon <will@kernel.org> Link: https://lore.kernel.org/r/20200731173824.107480-2-maz@kernel.org Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
parent
7d44b707aa
commit
82b05f0838
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@ -498,6 +498,39 @@ static void entry_task_switch(struct task_struct *next)
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__this_cpu_write(__entry_task, next);
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__this_cpu_write(__entry_task, next);
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}
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}
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/*
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* ARM erratum 1418040 handling, affecting the 32bit view of CNTVCT.
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* Assuming the virtual counter is enabled at the beginning of times:
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*
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* - disable access when switching from a 64bit task to a 32bit task
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* - enable access when switching from a 32bit task to a 64bit task
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*/
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static void erratum_1418040_thread_switch(struct task_struct *prev,
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struct task_struct *next)
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{
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bool prev32, next32;
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u64 val;
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if (!(IS_ENABLED(CONFIG_ARM64_ERRATUM_1418040) &&
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cpus_have_const_cap(ARM64_WORKAROUND_1418040)))
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return;
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prev32 = is_compat_thread(task_thread_info(prev));
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next32 = is_compat_thread(task_thread_info(next));
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if (prev32 == next32)
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return;
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val = read_sysreg(cntkctl_el1);
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if (!next32)
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val |= ARCH_TIMER_USR_VCT_ACCESS_EN;
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else
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val &= ~ARCH_TIMER_USR_VCT_ACCESS_EN;
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write_sysreg(val, cntkctl_el1);
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}
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/*
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/*
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* Thread switching.
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* Thread switching.
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*/
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*/
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@ -514,6 +547,7 @@ __notrace_funcgraph struct task_struct *__switch_to(struct task_struct *prev,
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uao_thread_switch(next);
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uao_thread_switch(next);
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ptrauth_thread_switch(next);
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ptrauth_thread_switch(next);
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ssbs_thread_switch(next);
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ssbs_thread_switch(next);
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erratum_1418040_thread_switch(prev, next);
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/*
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/*
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* Complete any pending TLB or cache maintenance on this CPU in case
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* Complete any pending TLB or cache maintenance on this CPU in case
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