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Subject[PATCH] Introduce TIF_IRET and use it to disable sysexit
This patch introduces a new flag called TIF_IRET and uses it in place
of TIF_SIGPENDING when that flag is used to force return via iret.

This avoids the overhead of calling do_signal and makes the code
easier to understand.


diff --exclude-from=/home/ldb/src/exclude -urNdp --exclude='speedtouch.*' --exclude='atmsar.*' linux-2.5.54/arch/i386/kernel/ioport.c linux-2.5.54-ldb/arch/i386/kernel/ioport.c
--- linux-2.5.54/arch/i386/kernel/ioport.c 2003-01-02 04:21:56.000000000 +0100
+++ linux-2.5.54-ldb/arch/i386/kernel/ioport.c 2003-01-04 19:06:07.000000000 +0100
@@ -124,6 +124,6 @@ asmlinkage int sys_iopl(unsigned long un
}
regs->eflags = (regs->eflags & 0xffffcfff) | (level << 12);
/* Make sure we return the long way (not sysenter) */
- set_thread_flag(TIF_SIGPENDING);
+ set_thread_flag(TIF_IRET);
return 0;
}
diff --exclude-from=/home/ldb/src/exclude -urNdp --exclude='speedtouch.*' --exclude='atmsar.*' linux-2.5.54/arch/i386/kernel/process.c linux-2.5.54-ldb/arch/i386/kernel/process.c
--- linux-2.5.54/arch/i386/kernel/process.c 2003-01-02 04:20:49.000000000 +0100
+++ linux-2.5.54-ldb/arch/i386/kernel/process.c 2003-01-04 19:06:07.000000000 +0100
@@ -561,7 +561,7 @@ asmlinkage int sys_execve(struct pt_regs
if (error == 0) {
current->ptrace &= ~PT_DTRACE;
/* Make sure we don't return using sysenter.. */
- set_thread_flag(TIF_SIGPENDING);
+ set_thread_flag(TIF_IRET);
}
putname(filename);
out:
diff --exclude-from=/home/ldb/src/exclude -urNdp --exclude='speedtouch.*' --exclude='atmsar.*' linux-2.5.54/arch/i386/kernel/signal.c linux-2.5.54-ldb/arch/i386/kernel/signal.c
--- linux-2.5.54/arch/i386/kernel/signal.c 2003-01-02 04:21:53.000000000 +0100
+++ linux-2.5.54-ldb/arch/i386/kernel/signal.c 2003-01-04 19:06:07.000000000 +0100
@@ -617,4 +619,6 @@ void do_notify_resume(struct pt_regs *re
/* deal with pending signal delivery */
if (thread_info_flags & _TIF_SIGPENDING)
do_signal(regs,oldset);
+
+ clear_thread_flag(TIF_IRET);
}
diff --exclude-from=/home/ldb/src/exclude -urNdp --exclude='speedtouch.*' --exclude='atmsar.*' linux-2.5.54/include/asm-i386/thread_info.h linux-2.5.54-ldb/include/asm-i386/thread_info.h
--- linux-2.5.54/include/asm-i386/thread_info.h 2003-01-02 04:21:09.000000000 +0100
+++ linux-2.5.54-ldb/include/asm-i386/thread_info.h 2003-01-04 19:06:07.000000000 +0100
@@ -110,6 +110,7 @@ static inline struct thread_info *curren
#define TIF_SIGPENDING 2 /* signal pending */
#define TIF_NEED_RESCHED 3 /* rescheduling necessary */
#define TIF_SINGLESTEP 4 /* restore singlestep on return to user mode */
+#define TIF_IRET 5 /* return with iret */
#define TIF_USEDFPU 16 /* FPU was used by this task this quantum (SMP) */
#define TIF_POLLING_NRFLAG 17 /* true if poll_idle() is polling TIF_NEED_RESCHED */

@@ -118,6 +119,7 @@ static inline struct thread_info *curren
#define _TIF_SIGPENDING (1<<TIF_SIGPENDING)
#define _TIF_NEED_RESCHED (1<<TIF_NEED_RESCHED)
#define _TIF_SINGLESTEP (1<<TIF_SINGLESTEP)
+#define _TIF_IRET (1<<TIF_IRET)
#define _TIF_USEDFPU (1<<TIF_USEDFPU)
#define _TIF_POLLING_NRFLAG (1<<TIF_POLLING_NRFLAG)
[unhandled content-type:application/pgp-signature]
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