lkml.org 
[lkml]   [2021]   [Jun]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH v8 18/19] arm64: Remove logic to kill 32-bit tasks on 64-bit-only cores
    Date
    The scheduler now knows enough about these braindead systems to place
    32-bit tasks accordingly, so throw out the safety checks and allow the
    ret-to-user path to avoid do_notify_resume() if there is nothing to do.

    Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
    Signed-off-by: Will Deacon <will@kernel.org>
    ---
    arch/arm64/kernel/process.c | 14 +-------------
    arch/arm64/kernel/signal.c | 26 --------------------------
    2 files changed, 1 insertion(+), 39 deletions(-)

    diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
    index 3aea06fdd1f9..5581c376644e 100644
    --- a/arch/arm64/kernel/process.c
    +++ b/arch/arm64/kernel/process.c
    @@ -528,15 +528,6 @@ static void erratum_1418040_thread_switch(struct task_struct *prev,
    write_sysreg(val, cntkctl_el1);
    }

    -static void compat_thread_switch(struct task_struct *next)
    -{
    - if (!is_compat_thread(task_thread_info(next)))
    - return;
    -
    - if (static_branch_unlikely(&arm64_mismatched_32bit_el0))
    - set_tsk_thread_flag(next, TIF_NOTIFY_RESUME);
    -}
    -
    static void update_sctlr_el1(u64 sctlr)
    {
    /*
    @@ -578,7 +569,6 @@ __notrace_funcgraph struct task_struct *__switch_to(struct task_struct *prev,
    ssbs_thread_switch(next);
    erratum_1418040_thread_switch(prev, next);
    ptrauth_thread_switch_user(next);
    - compat_thread_switch(next);

    /*
    * Complete any pending TLB or cache maintenance on this CPU in case
    @@ -680,10 +670,8 @@ void arch_setup_new_exec(void)
    * at the point of execve(), although we try a bit harder to
    * honour the cpuset hierarchy.
    */
    - if (static_branch_unlikely(&arm64_mismatched_32bit_el0)) {
    + if (static_branch_unlikely(&arm64_mismatched_32bit_el0))
    force_compatible_cpus_allowed_ptr(current);
    - set_tsk_thread_flag(current, TIF_NOTIFY_RESUME);
    - }
    } else if (static_branch_unlikely(&arm64_mismatched_32bit_el0)) {
    relax_compatible_cpus_allowed_ptr(current);
    }
    diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
    index f8192f4ae0b8..6237486ff6bb 100644
    --- a/arch/arm64/kernel/signal.c
    +++ b/arch/arm64/kernel/signal.c
    @@ -911,19 +911,6 @@ static void do_signal(struct pt_regs *regs)
    restore_saved_sigmask();
    }

    -static bool cpu_affinity_invalid(struct pt_regs *regs)
    -{
    - if (!compat_user_mode(regs))
    - return false;
    -
    - /*
    - * We're preemptible, but a reschedule will cause us to check the
    - * affinity again.
    - */
    - return !cpumask_test_cpu(raw_smp_processor_id(),
    - system_32bit_el0_cpumask());
    -}
    -
    asmlinkage void do_notify_resume(struct pt_regs *regs,
    unsigned long thread_flags)
    {
    @@ -951,19 +938,6 @@ asmlinkage void do_notify_resume(struct pt_regs *regs,
    if (thread_flags & _TIF_NOTIFY_RESUME) {
    tracehook_notify_resume(regs);
    rseq_handle_notify_resume(NULL, regs);
    -
    - /*
    - * If we reschedule after checking the affinity
    - * then we must ensure that TIF_NOTIFY_RESUME
    - * is set so that we check the affinity again.
    - * Since tracehook_notify_resume() clears the
    - * flag, ensure that the compiler doesn't move
    - * it after the affinity check.
    - */
    - barrier();
    -
    - if (cpu_affinity_invalid(regs))
    - force_sig(SIGKILL);
    }

    if (thread_flags & _TIF_FOREIGN_FPSTATE)
    --
    2.32.0.rc0.204.g9fa02ecfa5-goog
    \
     
     \ /
      Last update: 2021-06-02 18:50    [W:4.077 / U:0.644 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site