From 1b2bc75c1bde6581d2694cb3ed7fb06b69685008 Mon Sep 17 00:00:00 2001 From: Ralf Baechle Date: Tue, 23 Jun 2009 10:00:31 +0100 Subject: MIPS: Add arch generic CPU hotplug Each platform has to add support for CPU hotplugging itself by providing suitable definitions for the cpu_disable and cpu_die of the smp_ops methods and setting SYS_SUPPORTS_HOTPLUG_CPU. A platform should only set SYS_SUPPORTS_HOTPLUG_CPU once all it's smp_ops definitions have the necessary changes. This patch contains the changes to the dummy smp_ops definition for uni-processor systems. Parts of the code contributed by Cavium Inc. Signed-off-by: Ralf Baechle --- arch/mips/kernel/process.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) (limited to 'arch/mips/kernel/process.c') diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c index 1eaaa450e20c..c09d681b7181 100644 --- a/arch/mips/kernel/process.c +++ b/arch/mips/kernel/process.c @@ -50,10 +50,15 @@ */ void __noreturn cpu_idle(void) { + int cpu; + + /* CPU is going idle. */ + cpu = smp_processor_id(); + /* endless idle loop with no priority at all */ while (1) { tick_nohz_stop_sched_tick(1); - while (!need_resched()) { + while (!need_resched() && cpu_online(cpu)) { #ifdef CONFIG_MIPS_MT_SMTC extern void smtc_idle_loop_hook(void); @@ -62,6 +67,12 @@ void __noreturn cpu_idle(void) if (cpu_wait) (*cpu_wait)(); } +#ifdef CONFIG_HOTPLUG_CPU + if (!cpu_online(cpu) && !cpu_isset(cpu, cpu_callin_map) && + (system_state == SYSTEM_RUNNING || + system_state == SYSTEM_BOOTING)) + play_dead(); +#endif tick_nohz_restart_sched_tick(); preempt_enable_no_resched(); schedule(); -- cgit v1.2.3 From 484889fc85a223ef56edc31828b86751b2296b7c Mon Sep 17 00:00:00 2001 From: David Daney Date: Wed, 8 Jul 2009 10:07:50 -0700 Subject: MIPS: Avoid clobbering struct pt_regs in kthreads The resume() implementation octeon_switch.S examines the saved cp0_status register. We were clobbering the entire pt_regs structure in kernel threads leading to random crashes. When switching away from a kernel thread, the saved cp0_status is examined and if bit 30 is set it is cleared and the CP2 state saved into the pt_regs structure. Since the kernel thread stack overlaid the pt_regs structure this resulted in a corrupt stack. When the kthread with the corrupt stack was resumed, it could crash if it used any of the data in the stack that was clobbered. We fix it by moving the kernel thread stack down so it doesn't overlay pt_regs. Signed-off-by: David Daney Signed-off-by: Ralf Baechle --- arch/mips/include/asm/processor.h | 5 +++-- arch/mips/kernel/head.S | 3 ++- arch/mips/kernel/process.c | 4 +++- 3 files changed, 8 insertions(+), 4 deletions(-) (limited to 'arch/mips/kernel/process.c') diff --git a/arch/mips/include/asm/processor.h b/arch/mips/include/asm/processor.h index 0f926aa0cb47..087a8884ef06 100644 --- a/arch/mips/include/asm/processor.h +++ b/arch/mips/include/asm/processor.h @@ -311,8 +311,9 @@ extern void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long unsigned long get_wchan(struct task_struct *p); -#define __KSTK_TOS(tsk) ((unsigned long)task_stack_page(tsk) + THREAD_SIZE - 32) -#define task_pt_regs(tsk) ((struct pt_regs *)__KSTK_TOS(tsk) - 1) +#define __KSTK_TOS(tsk) ((unsigned long)task_stack_page(tsk) + \ + THREAD_SIZE - 32 - sizeof(struct pt_regs)) +#define task_pt_regs(tsk) ((struct pt_regs *)__KSTK_TOS(tsk)) #define KSTK_EIP(tsk) (task_pt_regs(tsk)->cp0_epc) #define KSTK_ESP(tsk) (task_pt_regs(tsk)->regs[29]) #define KSTK_STATUS(tsk) (task_pt_regs(tsk)->cp0_status) diff --git a/arch/mips/kernel/head.S b/arch/mips/kernel/head.S index 492a0a8d70fb..531ce7b16124 100644 --- a/arch/mips/kernel/head.S +++ b/arch/mips/kernel/head.S @@ -188,7 +188,8 @@ NESTED(kernel_entry, 16, sp) # kernel entry point MTC0 zero, CP0_CONTEXT # clear context register PTR_LA $28, init_thread_union - PTR_LI sp, _THREAD_SIZE - 32 + /* Set the SP after an empty pt_regs. */ + PTR_LI sp, _THREAD_SIZE - 32 - PT_SIZE PTR_ADDU sp, $28 set_saved_sp sp, t0, t1 PTR_SUBU sp, 4 * SZREG # init stack pointer diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c index c09d681b7181..f3d73e1831c1 100644 --- a/arch/mips/kernel/process.c +++ b/arch/mips/kernel/process.c @@ -115,7 +115,7 @@ int copy_thread(unsigned long clone_flags, unsigned long usp, { struct thread_info *ti = task_thread_info(p); struct pt_regs *childregs; - long childksp; + unsigned long childksp; p->set_child_tid = p->clear_child_tid = NULL; childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32; @@ -132,6 +132,8 @@ int copy_thread(unsigned long clone_flags, unsigned long usp, /* set up new TSS. */ childregs = (struct pt_regs *) childksp - 1; + /* Put the stack after the struct pt_regs. */ + childksp = (unsigned long) childregs; *childregs = *regs; childregs->regs[7] = 0; /* Clear error flag */ -- cgit v1.2.3