linuxsh-dev

duplicated syscall checks

[Hideo S. <sa...@de...>]

Hi Paul,

When I run spawn that is one of benchmark programs on unixbench-4.1.0, an error is asserted as follows.

% spawn 30
Illegal instruction

The caused PC is 0x4007fe, but the PC should be 0x400800, please refer to appended spawn's disassembled list. The 'report' is handled by alarm signal.

When '-ERESTARTNOINTR' is returned from fork syscall, do_signal() subtracts 2 from the address that is handled by alarm signal.

I think that the following patch can avoid this problem because the handled function does not come from a system call.

--- arch/sh/kernel/signal.c.org	Mon Feb  5 03:44:54 2007
+++ arch/sh/kernel/signal.c	Thu Mar  1 11:14:54 2007
@@ -583,16 +583,17 @@ static void do_signal(struct pt_regs *re
 		/* Whee!  Actually deliver the signal.  */
 		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,
 			 * and will be restored by sigreturn, so we can simply
 			 * clear the TIF_RESTORE_SIGMASK flag */
 			if (test_thread_flag(TIF_RESTORE_SIGMASK))
 				clear_thread_flag(TIF_RESTORE_SIGMASK);
+			regs->tra = -1;		/* disable syscall checks */
 		}
 	}
 
  no_signal:
 	/* Did we come from a system call? */
 	if (regs->tra >= 0) {
 		/* Restart the system call - no handlers present */
 		if (regs->regs[0] == -ERESTARTNOHAND ||

-a part of spawn's disassembled list----------------------------------
wake_me:
          004007e0 d005  MOV.L   @(H'14,PC),R0   ; 0x4007f8;*__sysv_signal@@GLIB
C_2.2
          004007e2 2f86  MOV.L   R8,@-R15        
          004007e4 6843  MOV     R4,R8           
          004007e6 4f22  STS.L   PR,@-R15        
          004007e8 400b  JSR     @R0             
          004007ea e40e  MOV     #H'E,R4         
          004007ec 4f26  LDS.L   @R15+,PR        
          004007ee d103  MOV.L   @(H'C,PC),R1    ; 0x4007fc;*alarm@@GLIBC_2.2
          004007f0 6483  MOV     R8,R4           
          004007f2 412b  JMP     @R1             
          004007f4 68f6  MOV.L   @R15+,R8        
          004007f6 0009  NOP                     
          004007f8 057c  MOV.B   @(R0,R7),R5     ; __sysv_signal@@GLIBC_2.2
          004007fa 0040  .data.w h'0040          
          004007fc 0608  .data.w h'0608          ; alarm@@GLIBC_2.2
          004007fe 0040  .data.w h'0040          
report:
          00400800 4f22  STS.L   PR,@-R15        
          00400802 d105  MOV.L   @(H'14,PC),R1   ; 0x400818;*_edata
          00400804 d005  MOV.L   @(H'14,PC),R0   ; 0x40081c;*fprintf@@GLIBC_2.2

Re: duplicated syscall checks

[Paul M. <le...@li...>]

On Thu, Mar 01, 2007 at 11:52:41AM +0900, Hideo Saito wrote:
> When '-ERESTARTNOINTR' is returned from fork syscall, do_signal()
> subtracts 2 from the address that is handled by alarm signal.
> 
This was already spotted and fixed in current git by Sakato-san, in the
case where we actually have a signal we should simply be returning.

I'll send this off for inclusion in the -stable tree.

commit fade884146b44be85b0987c8357194a16ea72f90
Author: Ryusuke Sakato <sa...@hs...>
Date:   Fri Feb 23 13:22:56 2007 +0900

    sh: Fix sigmask trampling in signal delivery.
    
    There was a missing return in do_signal() that caused the saved
    sigmask to be written back after having successfully delivered
    the signal.
    
    Signed-off-by: Ryusuke Sakato <sa...@hs...>
    Signed-off-by: Paul Mundt <le...@li...>

diff --git a/arch/sh/kernel/signal.c b/arch/sh/kernel/signal.c
index 32f10a0..9f39ef1 100644
--- a/arch/sh/kernel/signal.c
+++ b/arch/sh/kernel/signal.c
@@ -589,6 +589,8 @@ static void do_signal(struct pt_regs *regs, unsigned int save_r0)
 			if (test_thread_flag(TIF_RESTORE_SIGMASK))
 				clear_thread_flag(TIF_RESTORE_SIGMASK);
 		}
+
+		return;
 	}
 
  no_signal:
@@ -598,7 +600,7 @@ static void do_signal(struct pt_regs *regs, unsigned int save_r0)
 		if (regs->regs[0] == -ERESTARTNOHAND ||
 		    regs->regs[0] == -ERESTARTSYS ||
 		    regs->regs[0] == -ERESTARTNOINTR) {
-		    	regs->regs[0] = save_r0;
+			regs->regs[0] = save_r0;
 			regs->pc -= 2;
 		} else if (regs->regs[0] == -ERESTART_RESTARTBLOCK) {
 			regs->pc -= 2;