This small commit introduces a global state of system calls for ARM making it possible for a debugger or checkpointing to gain information about another process' state with respect to system calls.
The patch is based on this proposal from Roland McGrath: https://patchwork.kernel.org/patch/32101/ Cc: Roland McGrath <[email protected]> Signed-off-by: Christoffer Dall <[email protected]> Acked-by: Oren Laadan <[email protected]> --- arch/arm/include/asm/syscall.h | 31 +++++++++++++++++++++++++++++++ arch/arm/kernel/asm-offsets.c | 1 + arch/arm/kernel/entry-common.S | 8 +++++++- arch/arm/kernel/ptrace.c | 2 -- arch/arm/kernel/signal.c | 14 +++++++------- 5 files changed, 46 insertions(+), 10 deletions(-) create mode 100644 arch/arm/include/asm/syscall.h diff --git a/arch/arm/include/asm/syscall.h b/arch/arm/include/asm/syscall.h new file mode 100644 index 0000000..3b3248f --- /dev/null +++ b/arch/arm/include/asm/syscall.h @@ -0,0 +1,31 @@ +/* + * syscalls.h - Linux syscall interfaces for ARM + * + * Copyright (c) 2010 Christoffer Dall + * + * This file is released under the GPLv2. + * See the file COPYING for more details. + */ + +#ifndef _ASM_ARM_SYSCALLS_H +#define _ASM_ARM_SYSCALLS_H + +static inline int syscall_get_nr(struct task_struct *task, + struct pt_regs *regs) +{ + return (int)(task_thread_info(task)->syscall); +} + +static inline long syscall_get_return_value(struct task_struct *task, + struct pt_regs *regs) +{ + return regs->ARM_r0; +} + +static inline long syscall_get_error(struct task_struct *task, + struct pt_regs *regs) +{ + return regs->ARM_r0; +} + +#endif /* _ASM_ARM_SYSCALLS_H */ diff --git a/arch/arm/kernel/asm-offsets.c b/arch/arm/kernel/asm-offsets.c index 4a88125..726a0ad 100644 --- a/arch/arm/kernel/asm-offsets.c +++ b/arch/arm/kernel/asm-offsets.c @@ -48,6 +48,7 @@ int main(void) DEFINE(TI_CPU, offsetof(struct thread_info, cpu)); DEFINE(TI_CPU_DOMAIN, offsetof(struct thread_info, cpu_domain)); DEFINE(TI_CPU_SAVE, offsetof(struct thread_info, cpu_context)); + DEFINE(TI_SYSCALL, offsetof(struct thread_info, syscall)); DEFINE(TI_USED_CP, offsetof(struct thread_info, used_cp)); DEFINE(TI_TP_VALUE, offsetof(struct thread_info, tp_value)); DEFINE(TI_FPSTATE, offsetof(struct thread_info, fpstate)); diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S index 2c1db77..f694f4d 100644 --- a/arch/arm/kernel/entry-common.S +++ b/arch/arm/kernel/entry-common.S @@ -30,6 +30,9 @@ ret_fast_syscall: tst r1, #_TIF_WORK_MASK bne fast_work_pending + mov r2, #-1 + str r2, [tsk, #TI_SYSCALL] + /* perform architecture specific actions before user return */ arch_ret_to_user r1, lr @@ -47,7 +50,6 @@ work_pending: tst r1, #_TIF_SIGPENDING|_TIF_NOTIFY_RESUME beq no_work_pending mov r0, sp @ 'regs' - mov r2, why @ 'syscall' bl do_notify_resume b ret_slow_syscall @ Check work again @@ -62,6 +64,9 @@ ret_slow_syscall: ldr r1, [tsk, #TI_FLAGS] tst r1, #_TIF_WORK_MASK bne work_pending + + mov r2, #-1 + str r2, [tsk, #TI_SYSCALL] no_work_pending: /* perform architecture specific actions before user return */ arch_ret_to_user r1, lr @@ -274,6 +279,7 @@ ENTRY(vector_swi) eor scno, scno, #__NR_SYSCALL_BASE @ check OS number #endif + str scno, [tsk, #TI_SYSCALL] @ store syscall nr. globally stmdb sp!, {r4, r5} @ push fifth and sixth args tst ip, #_TIF_SYSCALL_TRACE @ are we tracing syscalls? bne __sys_trace diff --git a/arch/arm/kernel/ptrace.c b/arch/arm/kernel/ptrace.c index a2ea385..44ab437 100644 --- a/arch/arm/kernel/ptrace.c +++ b/arch/arm/kernel/ptrace.c @@ -863,8 +863,6 @@ asmlinkage int syscall_trace(int why, struct pt_regs *regs, int scno) ip = regs->ARM_ip; regs->ARM_ip = why; - current_thread_info()->syscall = scno; - /* the 0x80 provides a way for the tracing parent to distinguish between a syscall stop and SIGTRAP delivery */ ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD) diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c index e7714f3..f695239 100644 --- a/arch/arm/kernel/signal.c +++ b/arch/arm/kernel/signal.c @@ -527,7 +527,7 @@ static inline void setup_syscall_restart(struct pt_regs *regs) static int handle_signal(unsigned long sig, struct k_sigaction *ka, siginfo_t *info, sigset_t *oldset, - struct pt_regs * regs, int syscall) + struct pt_regs *regs) { struct thread_info *thread = current_thread_info(); struct task_struct *tsk = current; @@ -537,7 +537,7 @@ handle_signal(unsigned long sig, struct k_sigaction *ka, /* * If we were from a system call, check for system call restarting... */ - if (syscall) { + if (thread->syscall != -1) { switch (regs->ARM_r0) { case -ERESTART_RESTARTBLOCK: case -ERESTARTNOHAND: @@ -601,7 +601,7 @@ 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 void do_signal(struct pt_regs *regs) { struct k_sigaction ka; siginfo_t info; @@ -629,7 +629,7 @@ static void do_signal(struct pt_regs *regs, int syscall) oldset = ¤t->saved_sigmask; else oldset = ¤t->blocked; - if (handle_signal(signr, &ka, &info, oldset, regs, syscall) == 0) { + if (handle_signal(signr, &ka, &info, oldset, regs) == 0) { /* * A signal was successfully delivered; the saved * sigmask will have been stored in the signal frame, @@ -647,7 +647,7 @@ static void do_signal(struct pt_regs *regs, int syscall) /* * No signal to deliver to the process - restart the syscall. */ - if (syscall) { + if (current_thread_info()->syscall != -1) { if (regs->ARM_r0 == -ERESTART_RESTARTBLOCK) { if (thumb_mode(regs)) { regs->ARM_r7 = __NR_restart_syscall - __NR_SYSCALL_BASE; @@ -689,10 +689,10 @@ static void do_signal(struct pt_regs *regs, int syscall) } asmlinkage void -do_notify_resume(struct pt_regs *regs, unsigned int thread_flags, int syscall) +do_notify_resume(struct pt_regs *regs, unsigned int thread_flags) { if (thread_flags & _TIF_SIGPENDING) - do_signal(regs, syscall); + do_signal(regs); if (thread_flags & _TIF_NOTIFY_RESUME) { clear_thread_flag(TIF_NOTIFY_RESUME); -- 1.5.6.5 _______________________________________________ Containers mailing list [email protected] https://lists.linux-foundation.org/mailman/listinfo/containers _______________________________________________ Devel mailing list [email protected] https://openvz.org/mailman/listinfo/devel
