From 3d8c1a013d78f32ee266097496cbd89b734b5fcb Mon Sep 17 00:00:00 2001 From: Mark Rutland Date: Thu, 20 May 2021 12:50:31 +0100 Subject: [PATCH] arm64: smp: initialize cpu offset earlier Now that we have a consistent place to initialize CPU context registers early in the boot path, let's also initialize the per-cpu offset here. This makes the primary and secondary boot paths more consistent, and allows for the use of per-cpu operations earlier, which will be necessary for instrumentation with KCSAN. Note that smp_prepare_boot_cpu() still needs to re-initialize CPU0's offset as immediately prior to this the per-cpu areas may be reallocated, and hence the boot-time offset may be stale. A comment is added to make this clear. Signed-off-by: Mark Rutland Cc: Ard Biesheuvel Cc: Catalin Marinas Cc: James Morse Cc: Marc Zyngier Cc: Suzuki Poulose Cc: Will Deacon Reviewed-by: Ard Biesheuvel Link: https://lore.kernel.org/r/20210520115031.18509-7-mark.rutland@arm.com Signed-off-by: Will Deacon --- arch/arm64/kernel/asm-offsets.c | 1 + arch/arm64/kernel/head.S | 17 +++++++++++------ arch/arm64/kernel/setup.c | 6 ------ arch/arm64/kernel/smp.c | 10 ++++++---- 4 files changed, 18 insertions(+), 16 deletions(-) diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c index 4a5e204c33af7..bd0fc23d8719c 100644 --- a/arch/arm64/kernel/asm-offsets.c +++ b/arch/arm64/kernel/asm-offsets.c @@ -27,6 +27,7 @@ int main(void) { DEFINE(TSK_ACTIVE_MM, offsetof(struct task_struct, active_mm)); + DEFINE(TSK_CPU, offsetof(struct task_struct, cpu)); BLANK(); DEFINE(TSK_TI_FLAGS, offsetof(struct task_struct, thread_info.flags)); DEFINE(TSK_TI_PREEMPT, offsetof(struct task_struct, thread_info.preempt_count)); diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S index e83b2899dce5b..070ed53c049d4 100644 --- a/arch/arm64/kernel/head.S +++ b/arch/arm64/kernel/head.S @@ -402,17 +402,22 @@ SYM_FUNC_END(__create_page_tables) * its location in the task stack. We reserve the entire pt_regs space * for consistency with user tasks and kthreads. */ - .macro init_cpu_task tsk, tmp + .macro init_cpu_task tsk, tmp1, tmp2 msr sp_el0, \tsk - ldr \tmp, [\tsk, #TSK_STACK] - add sp, \tmp, #THREAD_SIZE + ldr \tmp1, [\tsk, #TSK_STACK] + add sp, \tmp1, #THREAD_SIZE sub sp, sp, #PT_REGS_SIZE stp xzr, xzr, [sp, #S_STACKFRAME] add x29, sp, #S_STACKFRAME - scs_load \tsk, \tmp + scs_load \tsk, \tmp1 + + adr_l \tmp1, __per_cpu_offset + ldr w\tmp2, [\tsk, #TSK_CPU] + ldr \tmp1, [\tmp1, \tmp2, lsl #3] + set_this_cpu_offset \tmp1 .endm /* @@ -422,7 +427,7 @@ SYM_FUNC_END(__create_page_tables) */ SYM_FUNC_START_LOCAL(__primary_switched) adr_l x4, init_task - init_cpu_task x4, x5 + init_cpu_task x4, x5, x6 adr_l x8, vectors // load VBAR_EL1 with virtual msr vbar_el1, x8 // vector table address @@ -650,7 +655,7 @@ SYM_FUNC_START_LOCAL(__secondary_switched) ldr x2, [x0, #CPU_BOOT_TASK] cbz x2, __secondary_too_slow - init_cpu_task x2, x1 + init_cpu_task x2, x1, x3 #ifdef CONFIG_ARM64_PTR_AUTH ptrauth_keys_init_cpu x2, x3, x4, x5 diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c index 61845c0821d9d..b7a35a03e9b90 100644 --- a/arch/arm64/kernel/setup.c +++ b/arch/arm64/kernel/setup.c @@ -87,12 +87,6 @@ void __init smp_setup_processor_id(void) u64 mpidr = read_cpuid_mpidr() & MPIDR_HWID_BITMASK; set_cpu_logical_map(0, mpidr); - /* - * clear __my_cpu_offset on boot CPU to avoid hang caused by - * using percpu variable early, for example, lockdep will - * access percpu variable inside lock_release - */ - set_my_cpu_offset(0); pr_info("Booting Linux on physical CPU 0x%010lx [0x%08x]\n", (unsigned long)mpidr, read_cpuid_id()); } diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c index 73625cc39574b..2fe8fab886e2b 100644 --- a/arch/arm64/kernel/smp.c +++ b/arch/arm64/kernel/smp.c @@ -198,10 +198,7 @@ asmlinkage notrace void secondary_start_kernel(void) u64 mpidr = read_cpuid_mpidr() & MPIDR_HWID_BITMASK; struct mm_struct *mm = &init_mm; const struct cpu_operations *ops; - unsigned int cpu; - - cpu = task_cpu(current); - set_my_cpu_offset(per_cpu_offset(cpu)); + unsigned int cpu = smp_processor_id(); /* * All kernel threads share the same mm context; grab a @@ -448,6 +445,11 @@ void __init smp_cpus_done(unsigned int max_cpus) void __init smp_prepare_boot_cpu(void) { + /* + * The runtime per-cpu areas have been allocated by + * setup_per_cpu_areas(), and CPU0's boot time per-cpu area will be + * freed shortly, so we must move over to the runtime per-cpu area. + */ set_my_cpu_offset(per_cpu_offset(smp_processor_id())); cpuinfo_store_boot_cpu(); -- 2.30.2