From linux-arm-kernel Sat Sep 04 06:09:06 2021 From: Keith Packard Date: Sat, 04 Sep 2021 06:09:06 +0000 To: linux-arm-kernel Subject: [PATCH 1/3] ARM: Pass cpu number to secondary_start_kernel Message-Id: <20210904060908.1310204-2-keithp () keithp ! com> X-MARC-Message: https://marc.info/?l=linux-arm-kernel&m=163073600208783 Instead of pulling the CPU value out of the thread_info struct, pass it as an argument. When first initializing secondary processors, this is done by stashing the value in the secondary_data struct. When restarting idle processors, the previous CPU value is passed. Because the cpu is now known at the top of secondary_start_kernel, the per_cpu_offset value can now be set at this point, instead of in cpu_init where it was also incorrectly setting the per_cpu_offset for the boot processor before that value had been computed. Signed-off-by: Keith Packard --- arch/arm/include/asm/smp.h | 3 ++- arch/arm/kernel/head-nommu.S | 1 + arch/arm/kernel/head.S | 1 + arch/arm/kernel/setup.c | 6 ------ arch/arm/kernel/smp.c | 14 +++++++++----- 5 files changed, 13 insertions(+), 12 deletions(-) diff --git a/arch/arm/include/asm/smp.h b/arch/arm/include/asm/smp.h index 5d508f5d56c4..86a7fd721556 100644 --- a/arch/arm/include/asm/smp.h +++ b/arch/arm/include/asm/smp.h @@ -48,7 +48,7 @@ extern void set_smp_ipi_range(int ipi_base, int nr_ipi); * Called from platform specific assembly code, this is the * secondary CPU entry point. */ -asmlinkage void secondary_start_kernel(void); +asmlinkage void secondary_start_kernel(unsigned int cpu); /* @@ -61,6 +61,7 @@ struct secondary_data { }; unsigned long swapper_pg_dir; void *stack; + unsigned int cpu; }; extern struct secondary_data secondary_data; extern void secondary_startup(void); diff --git a/arch/arm/kernel/head-nommu.S b/arch/arm/kernel/head-nommu.S index 0fc814bbc34b..5aa8ef42717f 100644 --- a/arch/arm/kernel/head-nommu.S +++ b/arch/arm/kernel/head-nommu.S @@ -114,6 +114,7 @@ ENTRY(secondary_startup) add r12, r12, r10 ret r12 1: bl __after_proc_init + ldr r0, [r7, #16] @ set up cpu number ldr sp, [r7, #12] @ set up the stack pointer mov fp, #0 b secondary_start_kernel diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S index 7f62c5eccdf3..0e541af738e2 100644 --- a/arch/arm/kernel/head.S +++ b/arch/arm/kernel/head.S @@ -394,6 +394,7 @@ ENDPROC(secondary_startup_arm) ENTRY(__secondary_switched) ldr_l r7, secondary_data + 12 @ get secondary_data.stack + ldr_l r0, secondary_data + 16 @ get secondary_data.cpu mov sp, r7 mov fp, #0 b secondary_start_kernel diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c index 73ca7797b92f..ca0201635fac 100644 --- a/arch/arm/kernel/setup.c +++ b/arch/arm/kernel/setup.c @@ -532,12 +532,6 @@ void notrace cpu_init(void) BUG(); } - /* - * This only works on resume and secondary cores. For booting on the - * boot cpu, smp_prepare_boot_cpu is called after percpu area setup. - */ - set_my_cpu_offset(per_cpu_offset(cpu)); - cpu_proc_init(); /* diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c index 74679240a9d8..55cb1689a4b3 100644 --- a/arch/arm/kernel/smp.c +++ b/arch/arm/kernel/smp.c @@ -153,6 +153,7 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle) secondary_data.pgdir = virt_to_phys(idmap_pgd); secondary_data.swapper_pg_dir = get_arch_pgd(swapper_pg_dir); #endif + secondary_data.cpu = cpu; sync_cache_w(&secondary_data); /* @@ -373,11 +374,14 @@ void arch_cpu_idle_dead(void) * cpu initialisation. There's some initialisation which needs * to be repeated to undo the effects of taking the CPU offline. */ - __asm__("mov sp, %0\n" + __asm__("mov r0, %1\n" + " mov sp, %0\n" " mov fp, #0\n" " b secondary_start_kernel" : - : "r" (task_stack_page(current) + THREAD_SIZE - 8)); + : "r" (task_stack_page(current) + THREAD_SIZE - 8), + "r" (cpu) + : "r0"); } #endif /* CONFIG_HOTPLUG_CPU */ @@ -400,10 +404,11 @@ static void smp_store_cpu_info(unsigned int cpuid) * This is the secondary CPU boot entry. We're using this CPUs * idle thread stack, but a set of temporary page tables. */ -asmlinkage void secondary_start_kernel(void) +asmlinkage void secondary_start_kernel(unsigned int cpu) { struct mm_struct *mm = &init_mm; - unsigned int cpu; + + set_my_cpu_offset(per_cpu_offset(cpu)); secondary_biglittle_init(); @@ -420,7 +425,6 @@ asmlinkage void secondary_start_kernel(void) * All kernel threads share the same mm context; grab a * reference and switch to it. */ - cpu = smp_processor_id(); mmgrab(mm); current->active_mm = mm; cpumask_set_cpu(cpu, mm_cpumask(mm)); -- 2.33.0 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel