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arm: new way of handling ERESTART_RESTARTBLOCK

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new "syscall start" flag; handled in syscall_trace() by switching
syscall number to that of syscall_restart(2).  Restarts of that
kind (ERESTART_RESTARTBLOCK) are handled by setting that bit;
syscall number is not modified until the actual call.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2012-05-02 21:02:03 -04:00
parent 21c1176a72
commit 6b5c8045ec
3 changed files with 13 additions and 28 deletions
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5
arch/arm/include/asm/thread_info.h
View File

@ -148,6 +148,7 @@ extern int vfp_restore_user_hwstate(struct user_vfp __user *,
#define TIF_NOTIFY_RESUME 2 /* callback before returning to user */
#define TIF_SYSCALL_TRACE 8
#define TIF_SYSCALL_AUDIT 9
#define TIF_SYSCALL_RESTARTSYS 10
#define TIF_POLLING_NRFLAG 16
#define TIF_USING_IWMMXT 17
#define TIF_MEMDIE 18 /* is terminating due to OOM killer */
@ -163,9 +164,11 @@ extern int vfp_restore_user_hwstate(struct user_vfp __user *,
#define _TIF_USING_IWMMXT (1 << TIF_USING_IWMMXT)
#define _TIF_RESTORE_SIGMASK (1 << TIF_RESTORE_SIGMASK)
#define _TIF_SECCOMP (1 << TIF_SECCOMP)
#define _TIF_SYSCALL_RESTARTSYS (1 << TIF_SYSCALL_RESTARTSYS)
/* Checks for any syscall work in entry-common.S */
#define _TIF_SYSCALL_WORK (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT)
#define _TIF_SYSCALL_WORK (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \
_TIF_SYSCALL_RESTARTSYS)
/*
* Change these and you break ASM code in entry-common.S

3
arch/arm/kernel/ptrace.c
View File

@ -24,6 +24,7 @@
#include <linux/hw_breakpoint.h>
#include <linux/regset.h>
#include <linux/audit.h>
#include <linux/unistd.h>
#include <asm/pgtable.h>
#include <asm/traps.h>
@ -916,6 +917,8 @@ asmlinkage int syscall_trace(int why, struct pt_regs *regs, int scno)
audit_syscall_entry(AUDIT_ARCH_ARM, scno, regs->ARM_r0,
regs->ARM_r1, regs->ARM_r2, regs->ARM_r3);
if (why == 0 && test_and_clear_thread_flag(TIF_SYSCALL_RESTARTSYS))
scno = __NR_restart_syscall - __NR_SYSCALL_BASE;
if (!test_thread_flag(TIF_SYSCALL_TRACE))
return scno;
if (!(current->ptrace & PT_PTRACED))

33
arch/arm/kernel/signal.c
View File

@ -624,12 +624,10 @@ static void do_signal(struct pt_regs *regs, int syscall)
case -ERESTARTNOHAND:
case -ERESTARTSYS:
case -ERESTARTNOINTR:
case -ERESTART_RESTARTBLOCK:
regs->ARM_r0 = regs->ARM_ORIG_r0;
regs->ARM_pc = restart_addr;
break;
case -ERESTART_RESTARTBLOCK:
regs->ARM_r0 = -EINTR;
break;
}
}
@ -647,12 +645,14 @@ static void do_signal(struct pt_regs *regs, int syscall)
* debugger has chosen to restart at a different PC.
*/
if (regs->ARM_pc == restart_addr) {
if (retval == -ERESTARTNOHAND
if (retval == -ERESTARTNOHAND ||
retval == -ERESTART_RESTARTBLOCK
|| (retval == -ERESTARTSYS
&& !(ka.sa.sa_flags & SA_RESTART))) {
regs->ARM_r0 = -EINTR;
regs->ARM_pc = continue_addr;
}
clear_thread_flag(TIF_SYSCALL_RESTARTSYS);
}
if (test_thread_flag(TIF_RESTORE_SIGMASK))
@ -679,29 +679,8 @@ static void do_signal(struct pt_regs *regs, int syscall)
* 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);
}
#endif
}
}
&& regs->ARM_pc == restart_addr)
set_thread_flag(TIF_SYSCALL_RESTARTSYS);
}
/* If there's no signal to deliver, we just put the saved sigmask