Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754441Ab2KGJvd (ORCPT ); Wed, 7 Nov 2012 04:51:33 -0500 Received: from kiruna.synopsys.com ([198.182.44.80]:58058 "EHLO kiruna.synopsys.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754201Ab2KGJsj (ORCPT ); Wed, 7 Nov 2012 04:48:39 -0500 From: Vineet Gupta To: linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org Cc: tglx@linutronix.de, arnd@arndb.de, Vineet Gupta Subject: [RFC PATCH v1 16/31] ARC: Signal handling Date: Wed, 7 Nov 2012 10:47:39 +0100 Message-Id: <1352281674-2186-17-git-send-email-vgupta@synopsys.com> X-Mailer: git-send-email 1.7.0.4 In-Reply-To: <1352281674-2186-1-git-send-email-vgupta@synopsys.com> References: <1352281674-2186-1-git-send-email-vgupta@synopsys.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 13341 Lines: 446 Signed-off-by: Vineet Gupta --- arch/arc/include/asm/sigcontext.h | 23 +++ arch/arc/include/asm/signal.h | 27 +++ arch/arc/kernel/signal.c | 360 +++++++++++++++++++++++++++++++++++++ 3 files changed, 410 insertions(+), 0 deletions(-) create mode 100644 arch/arc/include/asm/sigcontext.h create mode 100644 arch/arc/include/asm/signal.h create mode 100644 arch/arc/kernel/signal.c diff --git a/arch/arc/include/asm/sigcontext.h b/arch/arc/include/asm/sigcontext.h new file mode 100644 index 0000000..f21b541 --- /dev/null +++ b/arch/arc/include/asm/sigcontext.h @@ -0,0 +1,23 @@ +/* + * 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 + +/* + * Signal context structure - contains all info to do with the state + * before the signal handler was invoked. Note: only add new entries + * to the end of the structure. + */ +struct sigcontext { + struct pt_regs 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 0000000..fad62f7 --- /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 + +#endif /* _ASM_ARC_SIGNAL_H */ diff --git a/arch/arc/kernel/signal.c b/arch/arc/kernel/signal.c new file mode 100644 index 0000000..bc834da --- /dev/null +++ b/arch/arc/kernel/signal.c @@ -0,0 +1,360 @@ +/* + * 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 + * + * 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 +#include +#include +#include +#include +#include +#include + +#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP))) + +asmlinkage int sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss) +{ + struct pt_regs *regs = task_pt_regs(current); + return do_sigaltstack(uss, uoss, regs->sp); +} + +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(*regs)); + 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 == 0) { + sigdelsetmask(&set, ~_BLOCKABLE); + set_current_blocked(&set); + } + + err |= __copy_from_user(regs, &(sf->uc.uc_mcontext.regs), + sizeof(*regs)); + + 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 = task_pt_regs(current); + + /* 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 (do_sigaltstack(&sf->uc.uc_stack, NULL, regs->sp) == -EFAULT) + 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; +} + +static int +setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, + sigset_t *set, struct pt_regs *regs) +{ + struct rt_sigframe __user *sf; + unsigned int magic = 0; + stack_t stk; + 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); + stk.ss_sp = (void __user *)current->sas_ss_sp; + stk.ss_flags = sas_ss_flags(regs->sp); + stk.ss_size = current->sas_ss_size; + err |= __copy_to_user(&sf->uc.uc_stack, &stk, sizeof(stk)); + + /* setup args 2 and 3 fo ruse rmode 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 = sig; + + /* 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; +} + +/* + * OK, we're invoking a handler + */ +static void +handle_signal(unsigned long sig, struct k_sigaction *ka, siginfo_t *info, + struct pt_regs *regs, int in_syscall) +{ + struct thread_info *thread = current_thread_info(); + sigset_t *oldset = sigmask_to_save(); + unsigned long usig = sig; + int ret; + + /* Syscall restarting based on the ret code and other criteria */ + if (in_syscall) { + 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; + } + } + + if (thread->exec_domain && thread->exec_domain->signal_invmap + && usig < 32) + usig = thread->exec_domain->signal_invmap[usig]; + + /* Set up the stack frame */ + ret = setup_rt_frame(usig, 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 insyscall; + + signr = get_signal_to_deliver(&info, &ka, regs, NULL); + + /* Are we from a system call? */ + insyscall = in_syscall(regs); + + if (signr > 0) { + handle_signal(signr, &ka, &info, regs, insyscall); + return; + } + + if (insyscall) { + /* 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); +} -- 1.7.4.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/