Messages in this thread Patch in this message | | | From | Brian Gerst <> | Subject | [PATCH 2/6] x86/smpboot: Use current_task to get idle thread | Date | Wed, 22 Feb 2023 17:12:57 -0500 |
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The idle_threads array is not populated during early boot. Use current_task instead, which is initialized to init_task for the boot CPU.
Also simplify start_cpu0(). Since the boot CPU never really goes offline, the GSBASE is still set up and can be used for per-cpu accesses.
Signed-off-by: Brian Gerst <brgerst@gmail.com> --- arch/x86/kernel/asm-offsets.c | 1 + arch/x86/kernel/head_64.S | 7 ++----- kernel/smpboot.c | 2 +- 3 files changed, 4 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kernel/asm-offsets.c b/arch/x86/kernel/asm-offsets.c index 8650f29387e0..445bce086717 100644 --- a/arch/x86/kernel/asm-offsets.c +++ b/arch/x86/kernel/asm-offsets.c @@ -114,6 +114,7 @@ static void __used common(void) OFFSET(TSS_sp1, tss_struct, x86_tss.sp1); OFFSET(TSS_sp2, tss_struct, x86_tss.sp2); OFFSET(X86_top_of_stack, pcpu_hot, top_of_stack); + OFFSET(X86_current_task, pcpu_hot, current_task); #ifdef CONFIG_CALL_DEPTH_TRACKING OFFSET(X86_call_depth, pcpu_hot, call_depth); #endif diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index c1253aa737ca..c32e5b06a9ce 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -315,7 +315,7 @@ SYM_INNER_LABEL(secondary_startup_64_no_verify, SYM_L_GLOBAL) movq %rcx, early_gdt_descr_base(%rip) /* Find the idle task stack */ - movq idle_threads(%rbx), %rcx + movq pcpu_hot + X86_current_task(%rbx), %rcx movq TASK_threadsp(%rcx), %rcx movq %rcx, initial_stack(%rip) #endif /* CONFIG_SMP */ @@ -460,12 +460,9 @@ SYM_CODE_END(secondary_startup_64) SYM_CODE_START(start_cpu0) ANNOTATE_NOENDBR UNWIND_HINT_EMPTY - /* Load the per-cpu base for CPU#0 */ - leaq __per_cpu_offset(%rip), %rbx - movq (%rbx), %rbx /* Find the idle task stack */ - movq idle_threads(%rbx), %rcx + movq PER_CPU_VAR(pcpu_hot) + X86_current_task, %rcx movq TASK_threadsp(%rcx), %rsp jmp .Ljump_to_C_code diff --git a/kernel/smpboot.c b/kernel/smpboot.c index a18a21dff9bc..2c7396da470c 100644 --- a/kernel/smpboot.c +++ b/kernel/smpboot.c @@ -25,7 +25,7 @@ * For the hotplug case we keep the task structs around and reuse * them. */ -DEFINE_PER_CPU(struct task_struct *, idle_threads); +static DEFINE_PER_CPU(struct task_struct *, idle_threads); struct task_struct *idle_thread_get(unsigned int cpu) { -- 2.39.2
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