diff options
Diffstat (limited to 'arch/arm/kernel/signal.c')
| -rw-r--r-- | arch/arm/kernel/signal.c | 346 |
1 files changed, 148 insertions, 198 deletions
diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c index 536c5d6b340..bd198343720 100644 --- a/arch/arm/kernel/signal.c +++ b/arch/arm/kernel/signal.c @@ -8,98 +8,23 @@ * published by the Free Software Foundation. */ #include <linux/errno.h> +#include <linux/random.h> #include <linux/signal.h> #include <linux/personality.h> -#include <linux/freezer.h> #include <linux/uaccess.h> #include <linux/tracehook.h> +#include <linux/uprobes.h> #include <asm/elf.h> #include <asm/cacheflush.h> +#include <asm/traps.h> #include <asm/ucontext.h> #include <asm/unistd.h> #include <asm/vfp.h> -#include "signal.h" +extern const unsigned long sigreturn_codes[7]; -/* - * For ARM syscalls, we encode the syscall number into the instruction. - */ -#define SWI_SYS_SIGRETURN (0xef000000|(__NR_sigreturn)|(__NR_OABI_SYSCALL_BASE)) -#define SWI_SYS_RT_SIGRETURN (0xef000000|(__NR_rt_sigreturn)|(__NR_OABI_SYSCALL_BASE)) -#define SWI_SYS_RESTART (0xef000000|__NR_restart_syscall|__NR_OABI_SYSCALL_BASE) - -/* - * With EABI, the syscall number has to be loaded into r7. - */ -#define MOV_R7_NR_SIGRETURN (0xe3a07000 | (__NR_sigreturn - __NR_SYSCALL_BASE)) -#define MOV_R7_NR_RT_SIGRETURN (0xe3a07000 | (__NR_rt_sigreturn - __NR_SYSCALL_BASE)) - -/* - * For Thumb syscalls, we pass the syscall number via r7. We therefore - * need two 16-bit instructions. - */ -#define SWI_THUMB_SIGRETURN (0xdf00 << 16 | 0x2700 | (__NR_sigreturn - __NR_SYSCALL_BASE)) -#define SWI_THUMB_RT_SIGRETURN (0xdf00 << 16 | 0x2700 | (__NR_rt_sigreturn - __NR_SYSCALL_BASE)) - -const unsigned long sigreturn_codes[7] = { - MOV_R7_NR_SIGRETURN, SWI_SYS_SIGRETURN, SWI_THUMB_SIGRETURN, - MOV_R7_NR_RT_SIGRETURN, SWI_SYS_RT_SIGRETURN, SWI_THUMB_RT_SIGRETURN, -}; - -/* - * Either we support OABI only, or we have EABI with the OABI - * compat layer enabled. In the later case we don't know if - * user space is EABI or not, and if not we must not clobber r7. - * Always using the OABI syscall solves that issue and works for - * all those cases. - */ -const unsigned long syscall_restart_code[2] = { - SWI_SYS_RESTART, /* swi __NR_restart_syscall */ - 0xe49df004, /* ldr pc, [sp], #4 */ -}; - -/* - * atomically swap in the new signal mask, and wait for a signal. - */ -asmlinkage int sys_sigsuspend(int restart, unsigned long oldmask, old_sigset_t mask) -{ - sigset_t blocked; - siginitset(&blocked, mask); - return sigsuspend(&blocked); -} - -asmlinkage int -sys_sigaction(int sig, const struct old_sigaction __user *act, - struct old_sigaction __user *oact) -{ - struct k_sigaction new_ka, old_ka; - int ret; - - if (act) { - old_sigset_t mask; - if (!access_ok(VERIFY_READ, act, sizeof(*act)) || - __get_user(new_ka.sa.sa_handler, &act->sa_handler) || - __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) || - __get_user(new_ka.sa.sa_flags, &act->sa_flags) || - __get_user(mask, &act->sa_mask)) - return -EFAULT; - siginitset(&new_ka.sa.sa_mask, mask); - } - - ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL); - - if (!ret && oact) { - if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) || - __put_user(old_ka.sa.sa_handler, &oact->sa_handler) || - __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) || - __put_user(old_ka.sa.sa_flags, &oact->sa_flags) || - __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask)) - return -EFAULT; - } - - return ret; -} +static unsigned long signal_return_offset; #ifdef CONFIG_CRUNCH static int preserve_crunch_context(struct crunch_sigframe __user *frame) @@ -314,7 +239,7 @@ asmlinkage int sys_rt_sigreturn(struct pt_regs *regs) if (restore_sigframe(regs, &frame->sig)) goto badframe; - if (do_sigaltstack(&frame->sig.uc.uc_stack, NULL, regs->ARM_sp) == -EFAULT) + if (restore_altstack(&frame->sig.uc.uc_stack)) goto badframe; return regs->ARM_r0; @@ -374,18 +299,12 @@ setup_sigframe(struct sigframe __user *sf, struct pt_regs *regs, sigset_t *set) } static inline void __user * -get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, int framesize) +get_sigframe(struct ksignal *ksig, struct pt_regs *regs, int framesize) { - unsigned long sp = regs->ARM_sp; + unsigned long sp = sigsp(regs->ARM_sp, ksig); void __user *frame; /* - * This is the X/Open sanctioned signal stack switching. - */ - if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(sp)) - sp = current->sas_ss_sp + current->sas_ss_size; - - /* * ATPCS B01 mandates 8-byte alignment */ frame = (void __user *)((sp - framesize) & ~7); @@ -399,11 +318,22 @@ get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, int framesize) return frame; } +/* + * translate the signal + */ +static inline int map_sig(int sig) +{ + struct thread_info *thread = current_thread_info(); + if (sig < 32 && thread->exec_domain && thread->exec_domain->signal_invmap) + sig = thread->exec_domain->signal_invmap[sig]; + return sig; +} + static int -setup_return(struct pt_regs *regs, struct k_sigaction *ka, - unsigned long __user *rc, void __user *frame, int usig) +setup_return(struct pt_regs *regs, struct ksignal *ksig, + unsigned long __user *rc, void __user *frame) { - unsigned long handler = (unsigned long)ka->sa.sa_handler; + unsigned long handler = (unsigned long)ksig->ka.sa.sa_handler; unsigned long retcode; int thumb = 0; unsigned long cpsr = regs->ARM_cpsr & ~(PSR_f | PSR_E_BIT); @@ -413,7 +343,7 @@ setup_return(struct pt_regs *regs, struct k_sigaction *ka, /* * Maybe we need to deliver a 32-bit signal to a 26-bit task. */ - if (ka->sa.sa_flags & SA_THIRTYTWO) + if (ksig->ka.sa.sa_flags & SA_THIRTYTWO) cpsr = (cpsr & ~MODE_MASK) | USR_MODE; #ifdef CONFIG_ARM_THUMB @@ -424,36 +354,53 @@ setup_return(struct pt_regs *regs, struct k_sigaction *ka, */ thumb = handler & 1; - if (thumb) { - cpsr |= PSR_T_BIT; #if __LINUX_ARM_ARCH__ >= 7 - /* clear the If-Then Thumb-2 execution state */ - cpsr &= ~PSR_IT_MASK; + /* + * Clear the If-Then Thumb-2 execution state + * ARM spec requires this to be all 000s in ARM mode + * Snapdragon S4/Krait misbehaves on a Thumb=>ARM + * signal transition without this. + */ + cpsr &= ~PSR_IT_MASK; #endif + + if (thumb) { + cpsr |= PSR_T_BIT; } else cpsr &= ~PSR_T_BIT; } #endif - if (ka->sa.sa_flags & SA_RESTORER) { - retcode = (unsigned long)ka->sa.sa_restorer; + if (ksig->ka.sa.sa_flags & SA_RESTORER) { + retcode = (unsigned long)ksig->ka.sa.sa_restorer; } else { unsigned int idx = thumb << 1; - if (ka->sa.sa_flags & SA_SIGINFO) + if (ksig->ka.sa.sa_flags & SA_SIGINFO) idx += 3; + /* + * Put the sigreturn code on the stack no matter which return + * mechanism we use in order to remain ABI compliant + */ if (__put_user(sigreturn_codes[idx], rc) || __put_user(sigreturn_codes[idx+1], rc+1)) return 1; +#ifdef CONFIG_MMU if (cpsr & MODE32_BIT) { + struct mm_struct *mm = current->mm; + /* - * 32-bit code can use the new high-page - * signal return code support. + * 32-bit code can use the signal return page + * except when the MPU has protected the vectors + * page from PL0 */ - retcode = KERN_SIGRETURN_CODE + (idx << 2) + thumb; - } else { + retcode = mm->context.sigpage + signal_return_offset + + (idx << 2) + thumb; + } else +#endif + { /* * Ensure that the instruction cache sees * the return code written onto the stack. @@ -465,7 +412,7 @@ setup_return(struct pt_regs *regs, struct k_sigaction *ka, } } - regs->ARM_r0 = usig; + regs->ARM_r0 = map_sig(ksig->sig); regs->ARM_sp = (unsigned long)frame; regs->ARM_lr = retcode; regs->ARM_pc = handler; @@ -475,9 +422,9 @@ setup_return(struct pt_regs *regs, struct k_sigaction *ka, } static int -setup_frame(int usig, struct k_sigaction *ka, sigset_t *set, struct pt_regs *regs) +setup_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs) { - struct sigframe __user *frame = get_sigframe(ka, regs, sizeof(*frame)); + struct sigframe __user *frame = get_sigframe(ksig, regs, sizeof(*frame)); int err = 0; if (!frame) @@ -490,36 +437,29 @@ setup_frame(int usig, struct k_sigaction *ka, sigset_t *set, struct pt_regs *reg err |= setup_sigframe(frame, regs, set); if (err == 0) - err = setup_return(regs, ka, frame->retcode, frame, usig); + err = setup_return(regs, ksig, frame->retcode, frame); return err; } static int -setup_rt_frame(int usig, struct k_sigaction *ka, siginfo_t *info, - sigset_t *set, struct pt_regs *regs) +setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs) { - struct rt_sigframe __user *frame = get_sigframe(ka, regs, sizeof(*frame)); - stack_t stack; + struct rt_sigframe __user *frame = get_sigframe(ksig, regs, sizeof(*frame)); int err = 0; if (!frame) return 1; - err |= copy_siginfo_to_user(&frame->info, info); + err |= copy_siginfo_to_user(&frame->info, &ksig->info); __put_user_error(0, &frame->sig.uc.uc_flags, err); __put_user_error(NULL, &frame->sig.uc.uc_link, err); - memset(&stack, 0, sizeof(stack)); - stack.ss_sp = (void __user *)current->sas_ss_sp; - stack.ss_flags = sas_ss_flags(regs->ARM_sp); - stack.ss_size = current->sas_ss_size; - err |= __copy_to_user(&frame->sig.uc.uc_stack, &stack, sizeof(stack)); - + err |= __save_altstack(&frame->sig.uc.uc_stack, regs->ARM_sp); err |= setup_sigframe(&frame->sig, regs, set); if (err == 0) - err = setup_return(regs, ka, frame->sig.retcode, frame, usig); + err = setup_return(regs, ksig, frame->sig.retcode, frame); if (err == 0) { /* @@ -537,40 +477,25 @@ setup_rt_frame(int usig, struct k_sigaction *ka, siginfo_t *info, /* * OK, we're invoking a handler */ -static void -handle_signal(unsigned long sig, struct k_sigaction *ka, - siginfo_t *info, struct pt_regs *regs) +static void handle_signal(struct ksignal *ksig, struct pt_regs *regs) { - struct thread_info *thread = current_thread_info(); - struct task_struct *tsk = current; sigset_t *oldset = sigmask_to_save(); - int usig = sig; int ret; /* - * translate the signal - */ - if (usig < 32 && thread->exec_domain && thread->exec_domain->signal_invmap) - usig = thread->exec_domain->signal_invmap[usig]; - - /* * Set up the stack frame */ - if (ka->sa.sa_flags & SA_SIGINFO) - ret = setup_rt_frame(usig, ka, info, oldset, regs); + if (ksig->ka.sa.sa_flags & SA_SIGINFO) + ret = setup_rt_frame(ksig, oldset, regs); else - ret = setup_frame(usig, ka, oldset, regs); + ret = setup_frame(ksig, oldset, regs); /* * Check that the resulting registers are actually sane. */ ret |= !valid_user_regs(regs); - if (ret != 0) { - force_sigsegv(sig, tsk); - return; - } - signal_delivered(sig, info, ka, regs, 0); + signal_setup_done(ret, ksig, 0); } /* @@ -582,12 +507,11 @@ handle_signal(unsigned long sig, struct k_sigaction *ka, * the kernel can handle, and then we build all the user-level signal handling * stack-frames in one go after that. */ -static void do_signal(struct pt_regs *regs, int syscall) +static int do_signal(struct pt_regs *regs, int syscall) { unsigned int retval = 0, continue_addr = 0, restart_addr = 0; - struct k_sigaction ka; - siginfo_t info; - int signr; + struct ksignal ksig; + int restart = 0; /* * If we were from a system call, check for system call restarting... @@ -602,15 +526,15 @@ static void do_signal(struct pt_regs *regs, int syscall) * debugger will see the already changed PSW. */ switch (retval) { + case -ERESTART_RESTARTBLOCK: + restart -= 2; case -ERESTARTNOHAND: case -ERESTARTSYS: case -ERESTARTNOINTR: + restart++; regs->ARM_r0 = regs->ARM_ORIG_r0; regs->ARM_pc = restart_addr; break; - case -ERESTART_RESTARTBLOCK: - regs->ARM_r0 = -EINTR; - break; } } @@ -618,69 +542,95 @@ static void do_signal(struct pt_regs *regs, int syscall) * Get the signal to deliver. When running under ptrace, at this * point the debugger may change all our registers ... */ - signr = get_signal_to_deliver(&info, &ka, regs, NULL); - if (signr > 0) { - /* - * Depending on the signal settings we may need to revert the - * decision to restart the system call. But skip this if a - * debugger has chosen to restart at a different PC. - */ - if (regs->ARM_pc == restart_addr) { - if (retval == -ERESTARTNOHAND + /* + * Depending on the signal settings we may need to revert the + * decision to restart the system call. But skip this if a + * debugger has chosen to restart at a different PC. + */ + if (get_signal(&ksig)) { + /* handler */ + if (unlikely(restart) && regs->ARM_pc == restart_addr) { + if (retval == -ERESTARTNOHAND || + retval == -ERESTART_RESTARTBLOCK || (retval == -ERESTARTSYS - && !(ka.sa.sa_flags & SA_RESTART))) { + && !(ksig.ka.sa.sa_flags & SA_RESTART))) { regs->ARM_r0 = -EINTR; regs->ARM_pc = continue_addr; } } - - handle_signal(signr, &ka, &info, regs); - return; + handle_signal(&ksig, regs); + } else { + /* no handler */ + restore_saved_sigmask(); + if (unlikely(restart) && regs->ARM_pc == restart_addr) { + regs->ARM_pc = continue_addr; + return restart; + } } + return 0; +} - if (syscall) { - /* - * Handle restarting a different system call. As above, - * if a debugger has chosen to restart at a different PC, - * ignore the restart. - */ - if (retval == -ERESTART_RESTARTBLOCK - && regs->ARM_pc == continue_addr) { - if (thumb_mode(regs)) { - regs->ARM_r7 = __NR_restart_syscall - __NR_SYSCALL_BASE; - regs->ARM_pc -= 2; - } else { -#if defined(CONFIG_AEABI) && !defined(CONFIG_OABI_COMPAT) - regs->ARM_r7 = __NR_restart_syscall; - regs->ARM_pc -= 4; -#else - u32 __user *usp; - - regs->ARM_sp -= 4; - usp = (u32 __user *)regs->ARM_sp; - - if (put_user(regs->ARM_pc, usp) == 0) { - regs->ARM_pc = KERN_RESTART_CODE; - } else { - regs->ARM_sp += 4; - force_sigsegv(0, current); +asmlinkage int +do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall) +{ + do { + if (likely(thread_flags & _TIF_NEED_RESCHED)) { + schedule(); + } else { + if (unlikely(!user_mode(regs))) + return 0; + local_irq_enable(); + if (thread_flags & _TIF_SIGPENDING) { + int restart = do_signal(regs, syscall); + if (unlikely(restart)) { + /* + * Restart without handlers. + * Deal with it without leaving + * the kernel space. + */ + return restart; } -#endif + syscall = 0; + } else if (thread_flags & _TIF_UPROBE) { + clear_thread_flag(TIF_UPROBE); + uprobe_notify_resume(regs); + } else { + clear_thread_flag(TIF_NOTIFY_RESUME); + tracehook_notify_resume(regs); } } - } - - restore_saved_sigmask(); + local_irq_disable(); + thread_flags = current_thread_info()->flags; + } while (thread_flags & _TIF_WORK_MASK); + return 0; } -asmlinkage void -do_notify_resume(struct pt_regs *regs, unsigned int thread_flags, int syscall) +struct page *get_signal_page(void) { - if (thread_flags & _TIF_SIGPENDING) - do_signal(regs, syscall); + unsigned long ptr; + unsigned offset; + struct page *page; + void *addr; - if (thread_flags & _TIF_NOTIFY_RESUME) { - clear_thread_flag(TIF_NOTIFY_RESUME); - tracehook_notify_resume(regs); - } + page = alloc_pages(GFP_KERNEL, 0); + + if (!page) + return NULL; + + addr = page_address(page); + + /* Give the signal return code some randomness */ + offset = 0x200 + (get_random_int() & 0x7fc); + signal_return_offset = offset; + + /* + * Copy signal return handlers into the vector page, and + * set sigreturn to be a pointer to these. + */ + memcpy(addr + offset, sigreturn_codes, sizeof(sigreturn_codes)); + + ptr = (unsigned long)addr + offset; + flush_icache_range(ptr, ptr + sizeof(sigreturn_codes)); + + return page; } |