diff options
| -rw-r--r-- | arch/arc/Kconfig | 1 | ||||
| -rw-r--r-- | arch/arc/include/asm/entry.h | 35 | ||||
| -rw-r--r-- | arch/arc/include/asm/sigcontext.h | 22 | ||||
| -rw-r--r-- | arch/arc/include/asm/signal.h | 27 | ||||
| -rw-r--r-- | arch/arc/kernel/entry.S | 11 | ||||
| -rw-r--r-- | arch/arc/kernel/signal.c | 356 |
6 files changed, 449 insertions, 3 deletions
diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig index a4e9806ace23..756beffd20cb 100644 --- a/arch/arc/Kconfig +++ b/arch/arc/Kconfig @@ -20,6 +20,7 @@ config ARC select GENERIC_KERNEL_EXECVE select GENERIC_KERNEL_THREAD select GENERIC_PENDING_IRQ if SMP + select GENERIC_SIGALTSTACK select GENERIC_SMP_IDLE_THREAD select HAVE_GENERIC_HARDIRQS select MODULES_USE_ELF_RELA diff --git a/arch/arc/include/asm/entry.h b/arch/arc/include/asm/entry.h index 63705b12d911..6b42bf5c45ec 100644 --- a/arch/arc/include/asm/entry.h +++ b/arch/arc/include/asm/entry.h @@ -166,6 +166,41 @@ .endm /*-------------------------------------------------------------- + * RESTORE_CALLEE_SAVED_USER: + * This is called after do_signal where tracer might have changed callee regs + * thus we need to restore the reg file. + * Special case handling is required for r25 in case it is used by kernel + * for caching task ptr. Ptrace would have modified on-kernel-stack value of + * r25, which needs to be shoved back into task->thread.user_r25 where from + * Low level exception/ISR return code will retrieve to populate with rest of + * callee reg-file. + *-------------------------------------------------------------*/ +.macro RESTORE_CALLEE_SAVED_USER + + add sp, sp, 4 /* skip "callee_regs->stack_place_holder" */ + +#ifdef CONFIG_ARC_CURR_IN_REG + ld.ab r12, [sp, 4] + st r12, [r25, TASK_THREAD + THREAD_USER_R25] +#else + ld.ab r25, [sp, 4] +#endif + + ld.ab r24, [sp, 4] + ld.ab r23, [sp, 4] + ld.ab r22, [sp, 4] + ld.ab r21, [sp, 4] + ld.ab r20, [sp, 4] + ld.ab r19, [sp, 4] + ld.ab r18, [sp, 4] + ld.ab r17, [sp, 4] + ld.ab r16, [sp, 4] + ld.ab r15, [sp, 4] + ld.ab r14, [sp, 4] + ld.ab r13, [sp, 4] +.endm + +/*-------------------------------------------------------------- * Super FAST Restore callee saved regs by simply re-adjusting SP *-------------------------------------------------------------*/ .macro DISCARD_CALLEE_SAVED_USER diff --git a/arch/arc/include/asm/sigcontext.h b/arch/arc/include/asm/sigcontext.h new file mode 100644 index 000000000000..9678a11fc158 --- /dev/null +++ b/arch/arc/include/asm/sigcontext.h @@ -0,0 +1,22 @@ +/* + * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#ifndef _ASM_ARC_SIGCONTEXT_H +#define _ASM_ARC_SIGCONTEXT_H + +#include <asm/ptrace.h> + +/* + * Signal context structure - contains all info to do with the state + * before the signal handler was invoked. + */ +struct sigcontext { + struct user_regs_struct regs; +}; + +#endif /* _ASM_ARC_SIGCONTEXT_H */ diff --git a/arch/arc/include/asm/signal.h b/arch/arc/include/asm/signal.h new file mode 100644 index 000000000000..fad62f7f42d6 --- /dev/null +++ b/arch/arc/include/asm/signal.h @@ -0,0 +1,27 @@ +/* + * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * Amit Bhor, Sameer Dhavale: Codito Technologies 2004 + */ + +#ifndef _ASM_ARC_SIGNAL_H +#define _ASM_ARC_SIGNAL_H + +/* + * This is much needed for ARC sigreturn optimization. + * This allows uClibc to piggback the addr of a sigreturn stub in sigaction, + * which allows sigreturn based re-entry into kernel after handling signal. + * W/o this kernel needs to "synthesize" the sigreturn trampoline on user + * mode stack which in turn forces the following: + * -TLB Flush (after making the stack page executable) + * -Cache line Flush (to make I/D Cache lines coherent) + */ +#define SA_RESTORER 0x04000000 + +#include <asm-generic/signal.h> + +#endif /* _ASM_ARC_SIGNAL_H */ diff --git a/arch/arc/kernel/entry.S b/arch/arc/kernel/entry.S index ed08ac14fbc4..d625b77c14bd 100644 --- a/arch/arc/kernel/entry.S +++ b/arch/arc/kernel/entry.S @@ -470,7 +470,11 @@ resume_user_mode_begin: bbit0 r9, TIF_SIGPENDING, .Lchk_notify_resume - ; save CALLEE Regs. + ; Normal Trap/IRQ entry only saves Scratch (caller-saved) regs + ; in pt_reg since the "C" ABI (kernel code) will automatically + ; save/restore callee-saved regs. + ; + ; However, here we need to explicitly save callee regs because ; (i) If this signal causes coredump - full regfile needed ; (ii) If signal is SIGTRAP/SIGSTOP, task is being traced thus ; tracer might call PEEKUSR(CALLEE reg) @@ -484,8 +488,9 @@ resume_user_mode_begin: bl @do_signal - ; unwind SP for cheap discard of Callee saved Regs - DISCARD_CALLEE_SAVED_USER + ; Ideally we want to discard the Callee reg above, however if this was + ; a tracing signal, tracer could have done a POKEUSR(CALLEE reg) + RESTORE_CALLEE_SAVED_USER b resume_user_mode_begin ; loop back to start of U mode ret diff --git a/arch/arc/kernel/signal.c b/arch/arc/kernel/signal.c new file mode 100644 index 000000000000..ab8ed5a55461 --- /dev/null +++ b/arch/arc/kernel/signal.c @@ -0,0 +1,356 @@ +/* + * Signal Handling for ARC + * + * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * vineetg: Jan 2010 (Restarting of timer related syscalls) + * + * vineetg: Nov 2009 (Everything needed for TIF_RESTORE_SIGMASK) + * -do_signal() supports TIF_RESTORE_SIGMASK + * -do_signal() no loner needs oldset, required by OLD sys_sigsuspend + * -sys_rt_sigsuspend() now comes from generic code, so discard arch implemen + * -sys_sigsuspend() no longer needs to fudge ptregs, hence that arg removed + * -sys_sigsuspend() no longer loops for do_signal(), sets TIF_xxx and leaves + * the job to do_signal() + * + * vineetg: July 2009 + * -Modified Code to support the uClibc provided userland sigreturn stub + * to avoid kernel synthesing it on user stack at runtime, costing TLB + * probes and Cache line flushes. + * + * vineetg: July 2009 + * -In stash_usr_regs( ) and restore_usr_regs( ), save/restore of user regs + * in done in block copy rather than one word at a time. + * This saves around 2K of code and improves LMBench lat_sig <catch> + * + * rajeshwarr: Feb 2009 + * - Support for Realtime Signals + * + * vineetg: Aug 11th 2008: Bug #94183 + * -ViXS were still seeing crashes when using insmod to load drivers. + * It turned out that the code to change Execute permssions for TLB entries + * of user was not guarded for interrupts (mod_tlb_permission) + * This was cauing TLB entries to be overwritten on unrelated indexes + * + * Vineetg: July 15th 2008: Bug #94183 + * -Exception happens in Delay slot of a JMP, and before user space resumes, + * Signal is delivered (Ctrl + C) = >SIGINT. + * setup_frame( ) sets up PC,SP,BLINK to enable user space signal handler + * to run, but doesn't clear the Delay slot bit from status32. As a result, + * on resuming user mode, signal handler branches off to BTA of orig JMP + * -FIX: clear the DE bit from status32 in setup_frame( ) + * + * Rahul Trivedi, Kanika Nema: Codito Technologies 2004 + */ + +#include <linux/signal.h> +#include <linux/ptrace.h> +#include <linux/personality.h> +#include <linux/uaccess.h> +#include <linux/syscalls.h> +#include <linux/tracehook.h> +#include <asm/ucontext.h> + +struct rt_sigframe { + struct siginfo info; + struct ucontext uc; +#define MAGIC_SIGALTSTK 0x07302004 + unsigned int sigret_magic; +}; + +static int +stash_usr_regs(struct rt_sigframe __user *sf, struct pt_regs *regs, + sigset_t *set) +{ + int err; + err = __copy_to_user(&(sf->uc.uc_mcontext.regs), regs, + sizeof(sf->uc.uc_mcontext.regs.scratch)); + err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(sigset_t)); + + return err; +} + +static int restore_usr_regs(struct pt_regs *regs, struct rt_sigframe __user *sf) +{ + sigset_t set; + int err; + + err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set)); + if (!err) + set_current_blocked(&set); + + err |= __copy_from_user(regs, &(sf->uc.uc_mcontext.regs), + sizeof(sf->uc.uc_mcontext.regs.scratch)); + + return err; +} + +static inline int is_do_ss_needed(unsigned int magic) +{ + if (MAGIC_SIGALTSTK == magic) + return 1; + else + return 0; +} + +SYSCALL_DEFINE0(rt_sigreturn) +{ + struct rt_sigframe __user *sf; + unsigned int magic; + int err; + struct pt_regs *regs = current_pt_regs(); + + /* Always make any pending restarted system calls return -EINTR */ + current_thread_info()->restart_block.fn = do_no_restart_syscall; + + /* Since we stacked the signal on a word boundary, + * then 'sp' should be word aligned here. If it's + * not, then the user is trying to mess with us. + */ + if (regs->sp & 3) + goto badframe; + + sf = (struct rt_sigframe __force __user *)(regs->sp); + + if (!access_ok(VERIFY_READ, sf, sizeof(*sf))) + goto badframe; + + err = restore_usr_regs(regs, sf); + err |= __get_user(magic, &sf->sigret_magic); + if (err) + goto badframe; + + if (unlikely(is_do_ss_needed(magic))) + if (restore_altstack(&sf->uc.uc_stack)) + goto badframe; + + return regs->r0; + +badframe: + force_sig(SIGSEGV, current); + return 0; +} + +/* + * Determine which stack to use.. + */ +static inline void __user *get_sigframe(struct k_sigaction *ka, + struct pt_regs *regs, + unsigned long framesize) +{ + unsigned long sp = regs->sp; + 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; + + /* No matter what happens, 'sp' must be word + * aligned otherwise nasty things could happen + */ + + /* ATPCS B01 mandates 8-byte alignment */ + frame = (void __user *)((sp - framesize) & ~7); + + /* Check that we can actually write to the signal frame */ + if (!access_ok(VERIFY_WRITE, frame, framesize)) + frame = NULL; + + return frame; +} + +/* + * translate the signal + */ +static inline int map_sig(int sig) +{ + struct thread_info *thread = current_thread_info(); + if (thread->exec_domain && thread->exec_domain->signal_invmap + && sig < 32) + sig = thread->exec_domain->signal_invmap[sig]; + return sig; +} + +static int +setup_rt_frame(int signo, struct k_sigaction *ka, siginfo_t *info, + sigset_t *set, struct pt_regs *regs) +{ + struct rt_sigframe __user *sf; + unsigned int magic = 0; + int err = 0; + + sf = get_sigframe(ka, regs, sizeof(struct rt_sigframe)); + if (!sf) + return 1; + + /* + * SA_SIGINFO requires 3 args to signal handler: + * #1: sig-no (common to any handler) + * #2: struct siginfo + * #3: struct ucontext (completely populated) + */ + if (unlikely(ka->sa.sa_flags & SA_SIGINFO)) { + err |= copy_siginfo_to_user(&sf->info, info); + err |= __put_user(0, &sf->uc.uc_flags); + err |= __put_user(NULL, &sf->uc.uc_link); + err |= __save_altstack(&sf->uc.uc_stack, regs->sp); + + /* setup args 2 and 3 for user mode handler */ + regs->r1 = (unsigned long)&sf->info; + regs->r2 = (unsigned long)&sf->uc; + + /* + * small optim to avoid unconditonally calling do_sigaltstack + * in sigreturn path, now that we only have rt_sigreturn + */ + magic = MAGIC_SIGALTSTK; + } + + /* + * w/o SA_SIGINFO, struct ucontext is partially populated (only + * uc_mcontext/uc_sigmask) for kernel's normal user state preservation + * during signal handler execution. This works for SA_SIGINFO as well + * although the semantics are now overloaded (the same reg state can be + * inspected by userland: but are they allowed to fiddle with it ? + */ + err |= stash_usr_regs(sf, regs, set); + err |= __put_user(magic, &sf->sigret_magic); + if (err) + return err; + + /* #1 arg to the user Signal handler */ + regs->r0 = map_sig(signo); + + /* setup PC of user space signal handler */ + regs->ret = (unsigned long)ka->sa.sa_handler; + + /* + * handler returns using sigreturn stub provided already by userpsace + */ + BUG_ON(!(ka->sa.sa_flags & SA_RESTORER)); + regs->blink = (unsigned long)ka->sa.sa_restorer; + + /* User Stack for signal handler will be above the frame just carved */ + regs->sp = (unsigned long)sf; + + /* + * Bug 94183, Clear the DE bit, so that when signal handler + * starts to run, it doesn't use BTA + */ + regs->status32 &= ~STATUS_DE_MASK; + regs->status32 |= STATUS_L_MASK; + + return err; +} + +static void arc_restart_syscall(struct k_sigaction *ka, struct pt_regs *regs) +{ + switch (regs->r0) { + case -ERESTART_RESTARTBLOCK: + case -ERESTARTNOHAND: + /* + * ERESTARTNOHAND means that the syscall should + * only be restarted if there was no handler for + * the signal, and since we only get here if there + * is a handler, we don't restart + */ + regs->r0 = -EINTR; /* ERESTART_xxx is internal */ + break; + + case -ERESTARTSYS: + /* + * ERESTARTSYS means to restart the syscall if + * there is no handler or the handler was + * registered with SA_RESTART + */ + if (!(ka->sa.sa_flags & SA_RESTART)) { + regs->r0 = -EINTR; + break; + } + /* fallthrough */ + + case -ERESTARTNOINTR: + /* + * ERESTARTNOINTR means that the syscall should + * be called again after the signal handler returns. + * Setup reg state just as it was before doing the trap + * r0 has been clobbered with sys call ret code thus it + * needs to be reloaded with orig first arg to syscall + * in orig_r0. Rest of relevant reg-file: + * r8 (syscall num) and (r1 - r7) will be reset to + * their orig user space value when we ret from kernel + */ + regs->r0 = regs->orig_r0; + regs->ret -= 4; + break; + } +} + +/* + * OK, we're invoking a handler + */ +static void +handle_signal(unsigned long sig, struct k_sigaction *ka, siginfo_t *info, + struct pt_regs *regs) +{ + sigset_t *oldset = sigmask_to_save(); + int ret; + + /* Set up the stack frame */ + ret = setup_rt_frame(sig, ka, info, oldset, regs); + + if (ret) + force_sigsegv(sig, current); + else + signal_delivered(sig, info, ka, regs, 0); +} + +void do_signal(struct pt_regs *regs) +{ + struct k_sigaction ka; + siginfo_t info; + int signr; + int restart_scall; + + signr = get_signal_to_deliver(&info, &ka, regs, NULL); + + /* Are we from a system call? */ + restart_scall = in_syscall(regs); + + if (signr > 0) { + if (restart_scall) + arc_restart_syscall(&ka, regs); + + handle_signal(signr, &ka, &info, regs); + return; + } + + if (restart_scall) { + /* No handler for syscall: restart it */ + if (regs->r0 == -ERESTARTNOHAND || + regs->r0 == -ERESTARTSYS || regs->r0 == -ERESTARTNOINTR) { + regs->r0 = regs->orig_r0; + regs->ret -= 4; + } else if (regs->r0 == -ERESTART_RESTARTBLOCK) { + regs->r8 = __NR_restart_syscall; + regs->ret -= 4; + } + } + + /* If there's no signal to deliver, restore the saved sigmask back */ + restore_saved_sigmask(); +} + +void do_notify_resume(struct pt_regs *regs) +{ + /* + * ASM glue gaurantees that this is only called when returning to + * user mode + */ + if (test_and_clear_thread_flag(TIF_NOTIFY_RESUME)) + tracehook_notify_resume(regs); +} |