From 81783786d5cf4aa0d3e15bb0fac856aa8ebf1a76 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Thu, 19 Jul 2012 17:48:21 +0100 Subject: [PATCH] ARM: 7473/1: deal with handlerless restarts without leaving the kernel Signed-off-by: Al Viro Signed-off-by: Will Deacon Signed-off-by: Russell King --- arch/arm/kernel/entry-common.S | 7 ++++- arch/arm/kernel/signal.c | 50 ++++++++++++++++++++-------------- 2 files changed, 35 insertions(+), 22 deletions(-) diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S index 1873f653641c..8ae58c47dce6 100644 --- a/arch/arm/kernel/entry-common.S +++ b/arch/arm/kernel/entry-common.S @@ -54,7 +54,11 @@ work_pending: mov r0, sp @ 'regs' mov r2, why @ 'syscall' bl do_work_pending - b no_work_pending + tst r0, #1 + beq no_work_pending + ldmia sp, {r0 - r6} @ have to reload r0 - r6 + b local_restart @ ... and off we go + /* * "slow" syscall return path. "why" tells us if this was a real syscall. */ @@ -396,6 +400,7 @@ ENTRY(vector_swi) eor scno, scno, #__NR_SYSCALL_BASE @ check OS number #endif +local_restart: ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing stmdb sp!, {r4, r5} @ push fifth and sixth args diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c index 8756e5dcd377..99851cb9591d 100644 --- a/arch/arm/kernel/signal.c +++ b/arch/arm/kernel/signal.c @@ -569,12 +569,13 @@ 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; + int restart = 0; /* * If we were from a system call, check for system call restarting... @@ -589,10 +590,12 @@ static void do_signal(struct pt_regs *regs, int syscall) * debugger will see the already changed PSW. */ switch (retval) { + case -ERESTART_RESTARTBLOCK: + restart++; case -ERESTARTNOHAND: case -ERESTARTSYS: case -ERESTARTNOINTR: - case -ERESTART_RESTARTBLOCK: + restart++; regs->ARM_r0 = regs->ARM_ORIG_r0; regs->ARM_pc = restart_addr; break; @@ -604,13 +607,15 @@ static void do_signal(struct pt_regs *regs, int syscall) * point the debugger may change all our registers ... */ signr = get_signal_to_deliver(&info, &ka, regs, NULL); + /* + * 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) + restart = 0; 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 (unlikely(restart)) { if (retval == -ERESTARTNOHAND || retval == -ERESTART_RESTARTBLOCK || (retval == -ERESTARTSYS @@ -618,28 +623,23 @@ static void do_signal(struct pt_regs *regs, int syscall) regs->ARM_r0 = -EINTR; regs->ARM_pc = continue_addr; } - clear_thread_flag(TIF_SYSCALL_RESTARTSYS); } handle_signal(signr, &ka, &info, regs); - return; + 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 == restart_addr) + if (unlikely(restart)) { + if (restart > 1) set_thread_flag(TIF_SYSCALL_RESTARTSYS); + regs->ARM_pc = continue_addr; } restore_saved_sigmask(); + return restart; } -asmlinkage void +asmlinkage int do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall) { do { @@ -647,10 +647,17 @@ do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall) schedule(); } else { if (unlikely(!user_mode(regs))) - return; + return 0; local_irq_enable(); if (thread_flags & _TIF_SIGPENDING) { - do_signal(regs, syscall); + if (unlikely(do_signal(regs, syscall))) { + /* + * Restart without handlers. + * Deal with it without leaving + * the kernel space. + */ + return 1; + } syscall = 0; } else { clear_thread_flag(TIF_NOTIFY_RESUME); @@ -660,4 +667,5 @@ do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall) local_irq_disable(); thread_flags = current_thread_info()->flags; } while (thread_flags & _TIF_WORK_MASK); + return 0; } -- 2.39.2