diff options
| -rw-r--r-- | arch/um/include/kern_util.h | 3 | ||||
| -rw-r--r-- | arch/um/kernel/dyn.lds.S | 2 | ||||
| -rw-r--r-- | arch/um/kernel/init_task.c | 16 | ||||
| -rw-r--r-- | arch/um/kernel/irq.c | 111 | ||||
| -rw-r--r-- | arch/um/kernel/skas/process.c | 4 | ||||
| -rw-r--r-- | arch/um/kernel/uml.lds.S | 2 | ||||
| -rw-r--r-- | arch/um/os-Linux/signal.c | 40 | ||||
| -rw-r--r-- | arch/um/os-Linux/sys-i386/signal.c | 8 | ||||
| -rw-r--r-- | arch/um/os-Linux/sys-x86_64/signal.c | 6 | ||||
| -rw-r--r-- | include/asm-um/thread_info.h | 2 |
10 files changed, 180 insertions, 14 deletions
diff --git a/arch/um/include/kern_util.h b/arch/um/include/kern_util.h index 50a4969..8d7f7c1 100644 --- a/arch/um/include/kern_util.h +++ b/arch/um/include/kern_util.h @@ -117,4 +117,7 @@ extern void sigio_handler(int sig, union uml_pt_regs *regs); extern void copy_sc(union uml_pt_regs *regs, void *from); +unsigned long to_irq_stack(int sig, unsigned long *mask_out); +unsigned long from_irq_stack(int nested); + #endif diff --git a/arch/um/kernel/dyn.lds.S b/arch/um/kernel/dyn.lds.S index e36f92b..87a4e44 100644 --- a/arch/um/kernel/dyn.lds.S +++ b/arch/um/kernel/dyn.lds.S @@ -97,6 +97,8 @@ SECTIONS .data : { . = ALIGN(KERNEL_STACK_SIZE); /* init_task */ *(.data.init_task) + . = ALIGN(KERNEL_STACK_SIZE); + *(.data.init_irqstack) *(.data .data.* .gnu.linkonce.d.*) SORT(CONSTRUCTORS) } diff --git a/arch/um/kernel/init_task.c b/arch/um/kernel/init_task.c index f5385a3..d4f1d1a 100644 --- a/arch/um/kernel/init_task.c +++ b/arch/um/kernel/init_task.c @@ -1,5 +1,5 @@ -/* - * Copyright (C) 2000 Jeff Dike (jdike@karaya.com) +/* + * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,intel.linux}.com) * Licensed under the GPL */ @@ -33,14 +33,18 @@ EXPORT_SYMBOL(init_task); /* * Initial thread structure. * - * We need to make sure that this is 16384-byte aligned due to the + * We need to make sure that this is aligned due to the * way process stacks are handled. This is done by having a special * "init_task" linker map entry.. */ -union thread_union init_thread_union -__attribute__((__section__(".data.init_task"))) = -{ INIT_THREAD_INFO(init_task) }; +union thread_union init_thread_union + __attribute__((__section__(".data.init_task"))) = + { INIT_THREAD_INFO(init_task) }; + +union thread_union cpu0_irqstack + __attribute__((__section__(".data.init_irqstack"))) = + { INIT_THREAD_INFO(init_task) }; void unprotect_stack(unsigned long stack) { diff --git a/arch/um/kernel/irq.c b/arch/um/kernel/irq.c index a9651a1..dba04d8 100644 --- a/arch/um/kernel/irq.c +++ b/arch/um/kernel/irq.c @@ -32,6 +32,7 @@ #include "sigio.h" #include "um_malloc.h" #include "misc_constants.h" +#include "as-layout.h" /* * Generic, controller-independent functions: @@ -468,3 +469,113 @@ int init_aio_irq(int irq, char *name, irq_handler_t handler) out: return err; } + +/* + * IRQ stack entry and exit: + * + * Unlike i386, UML doesn't receive IRQs on the normal kernel stack + * and switch over to the IRQ stack after some preparation. We use + * sigaltstack to receive signals on a separate stack from the start. + * These two functions make sure the rest of the kernel won't be too + * upset by being on a different stack. The IRQ stack has a + * thread_info structure at the bottom so that current et al continue + * to work. + * + * to_irq_stack copies the current task's thread_info to the IRQ stack + * thread_info and sets the tasks's stack to point to the IRQ stack. + * + * from_irq_stack copies the thread_info struct back (flags may have + * been modified) and resets the task's stack pointer. + * + * Tricky bits - + * + * What happens when two signals race each other? UML doesn't block + * signals with sigprocmask, SA_DEFER, or sa_mask, so a second signal + * could arrive while a previous one is still setting up the + * thread_info. + * + * There are three cases - + * The first interrupt on the stack - sets up the thread_info and + * handles the interrupt + * A nested interrupt interrupting the copying of the thread_info - + * can't handle the interrupt, as the stack is in an unknown state + * A nested interrupt not interrupting the copying of the + * thread_info - doesn't do any setup, just handles the interrupt + * + * The first job is to figure out whether we interrupted stack setup. + * This is done by xchging the signal mask with thread_info->pending. + * If the value that comes back is zero, then there is no setup in + * progress, and the interrupt can be handled. If the value is + * non-zero, then there is stack setup in progress. In order to have + * the interrupt handled, we leave our signal in the mask, and it will + * be handled by the upper handler after it has set up the stack. + * + * Next is to figure out whether we are the outer handler or a nested + * one. As part of setting up the stack, thread_info->real_thread is + * set to non-NULL (and is reset to NULL on exit). This is the + * nesting indicator. If it is non-NULL, then the stack is already + * set up and the handler can run. + */ + +static unsigned long pending_mask; + +unsigned long to_irq_stack(int sig, unsigned long *mask_out) +{ + struct thread_info *ti; + unsigned long mask, old; + int nested; + + mask = xchg(&pending_mask, 1 << sig); + if(mask != 0){ + /* If any interrupts come in at this point, we want to + * make sure that their bits aren't lost by our + * putting our bit in. So, this loop accumulates bits + * until xchg returns the same value that we put in. + * When that happens, there were no new interrupts, + * and pending_mask contains a bit for each interrupt + * that came in. + */ + old = 1 << sig; + do { + old |= mask; + mask = xchg(&pending_mask, old); + } while(mask != old); + return 1; + } + + ti = current_thread_info(); + nested = (ti->real_thread != NULL); + if(!nested){ + struct task_struct *task; + struct thread_info *tti; + + task = cpu_tasks[ti->cpu].task; + tti = task_thread_info(task); + *ti = *tti; + ti->real_thread = tti; + task->stack = ti; + } + + mask = xchg(&pending_mask, 0); + *mask_out |= mask | nested; + return 0; +} + +unsigned long from_irq_stack(int nested) +{ + struct thread_info *ti, *to; + unsigned long mask; + + ti = current_thread_info(); + + pending_mask = 1; + + to = ti->real_thread; + current->stack = to; + ti->real_thread = NULL; + *to = *ti; + + mask = xchg(&pending_mask, 0); + return mask & ~1; +} + diff --git a/arch/um/kernel/skas/process.c b/arch/um/kernel/skas/process.c index a96ae1a..2a69a7c 100644 --- a/arch/um/kernel/skas/process.c +++ b/arch/um/kernel/skas/process.c @@ -163,8 +163,12 @@ static int start_kernel_proc(void *unused) extern int userspace_pid[]; +extern char cpu0_irqstack[]; + int start_uml_skas(void) { + stack_protections((unsigned long) &cpu0_irqstack); + set_sigstack(cpu0_irqstack, THREAD_SIZE); if(proc_mm) userspace_pid[0] = start_userspace(0); diff --git a/arch/um/kernel/uml.lds.S b/arch/um/kernel/uml.lds.S index f630127..bc59f97 100644 --- a/arch/um/kernel/uml.lds.S +++ b/arch/um/kernel/uml.lds.S @@ -59,6 +59,8 @@ SECTIONS { . = ALIGN(KERNEL_STACK_SIZE); /* init_task */ *(.data.init_task) + . = ALIGN(KERNEL_STACK_SIZE); + *(.data.init_irqstack) *(.data) *(.gnu.linkonce.d*) CONSTRUCTORS diff --git a/arch/um/os-Linux/signal.c b/arch/um/os-Linux/signal.c index 420ee86..18e5c8b 100644 --- a/arch/um/os-Linux/signal.c +++ b/arch/um/os-Linux/signal.c @@ -117,6 +117,46 @@ void remove_sigstack(void) void (*handlers[_NSIG])(int sig, struct sigcontext *sc); +void handle_signal(int sig, struct sigcontext *sc) +{ + unsigned long pending = 0; + + do { + int nested, bail; + + /* + * pending comes back with one bit set for each + * interrupt that arrived while setting up the stack, + * plus a bit for this interrupt, plus the zero bit is + * set if this is a nested interrupt. + * If bail is true, then we interrupted another + * handler setting up the stack. In this case, we + * have to return, and the upper handler will deal + * with this interrupt. + */ + bail = to_irq_stack(sig, &pending); + if(bail) + return; + + nested = pending & 1; + pending &= ~1; + + while((sig = ffs(pending)) != 0){ + sig--; + pending &= ~(1 << sig); + (*handlers[sig])(sig, sc); + } + + /* Again, pending comes back with a mask of signals + * that arrived while tearing down the stack. If this + * is non-zero, we just go back, set up the stack + * again, and handle the new interrupts. + */ + if(!nested) + pending = from_irq_stack(nested); + } while(pending); +} + extern void hard_handler(int sig); void set_handler(int sig, void (*handler)(int), int flags, ...) diff --git a/arch/um/os-Linux/sys-i386/signal.c b/arch/um/os-Linux/sys-i386/signal.c index 0d3eae5..f311609 100644 --- a/arch/um/os-Linux/sys-i386/signal.c +++ b/arch/um/os-Linux/sys-i386/signal.c @@ -1,15 +1,13 @@ /* - * Copyright (C) 2006 Jeff Dike (jdike@addtoit.com) + * Copyright (C) 2006 Jeff Dike (jdike@{addtoit,linux.intel}.com) * Licensed under the GPL */ #include <signal.h> -extern void (*handlers[])(int sig, struct sigcontext *sc); +extern void handle_signal(int sig, struct sigcontext *sc); void hard_handler(int sig) { - struct sigcontext *sc = (struct sigcontext *) (&sig + 1); - - (*handlers[sig])(sig, sc); + handle_signal(sig, (struct sigcontext *) (&sig + 1)); } diff --git a/arch/um/os-Linux/sys-x86_64/signal.c b/arch/um/os-Linux/sys-x86_64/signal.c index 3f369e5..82a3888 100644 --- a/arch/um/os-Linux/sys-x86_64/signal.c +++ b/arch/um/os-Linux/sys-x86_64/signal.c @@ -1,16 +1,16 @@ /* - * Copyright (C) 2006 Jeff Dike (jdike@addtoit.com) + * Copyright (C) 2006 Jeff Dike (jdike@{addtoit,linux.intel}.com) * Licensed under the GPL */ #include <signal.h> -extern void (*handlers[])(int sig, struct sigcontext *sc); +extern void handle_signal(int sig, struct sigcontext *sc); void hard_handler(int sig) { struct ucontext *uc; asm("movq %%rdx, %0" : "=r" (uc)); - (*handlers[sig])(sig, (struct sigcontext *) &uc->uc_mcontext); + handle_signal(sig, (struct sigcontext *) &uc->uc_mcontext); } diff --git a/include/asm-um/thread_info.h b/include/asm-um/thread_info.h index 261e2f4..18a13ba 100644 --- a/include/asm-um/thread_info.h +++ b/include/asm-um/thread_info.h @@ -22,6 +22,7 @@ struct thread_info { 0-0xBFFFFFFF for user 0-0xFFFFFFFF for kernel */ struct restart_block restart_block; + struct thread_info *real_thread; /* Points to non-IRQ stack */ }; #define INIT_THREAD_INFO(tsk) \ @@ -35,6 +36,7 @@ struct thread_info { .restart_block = { \ .fn = do_no_restart_syscall, \ }, \ + .real_thread = NULL, \ } #define init_thread_info (init_thread_union.thread_info) |