Merge branch 'audit' of git://git.linaro.org/people/rmk/linux-arm

Pull ARM audit/signal updates from Russell King:
 "ARM audit/signal handling updates from Al and Will.  This improves on
  the work Viro did last merge window, and sorts out some of the issues
  found with that work."

* 'audit' of git://git.linaro.org/people/rmk/linux-arm:
  ARM: 7475/1: sys_trace: allow all syscall arguments to be updated via ptrace
  ARM: 7474/1: get rid of TIF_SYSCALL_RESTARTSYS
  ARM: 7473/1: deal with handlerless restarts without leaving the kernel
  ARM: 7472/1: pull all work_pending logics into C function
  ARM: 7471/1: Revert "7442/1: Revert "remove unused restart trampoline""
  ARM: 7470/1: Revert "7443/1: Revert "new way of handling ERESTART_RESTARTBLOCK""

Author: torvalds

arch/arm/kernel/entry-common.S

@@ -51,23 +51,15 @@ ret_fast_syscall:
 fast_work_pending:
 	str	r0, [sp, #S_R0+S_OFF]!		@ returned r0
 work_pending:
-	tst	r1, #_TIF_NEED_RESCHED
-	bne	work_resched
-	/*
-	 * TIF_SIGPENDING or TIF_NOTIFY_RESUME must've been set if we got here
-	 */
-	ldr	r2, [sp, #S_PSR]
 	mov	r0, sp				@ 'regs'
-	tst	r2, #15				@ are we returning to user mode?
-	bne	no_work_pending			@ no?  just leave, then...
 	mov	r2, why				@ 'syscall'
-	tst	r1, #_TIF_SIGPENDING		@ delivering a signal?
-	movne	why, #0				@ prevent further restarts
-	bl	do_notify_resume
-	b	ret_slow_syscall		@ Check work again
+	bl	do_work_pending
+	cmp	r0, #0
+	beq	no_work_pending
+	movlt	scno, #(__NR_restart_syscall - __NR_SYSCALL_BASE)
+	ldmia	sp, {r0 - r6}			@ have to reload r0 - r6
+	b	local_restart			@ ... and off we go
 
-work_resched:
-	bl	schedule
 /*
  * "slow" syscall return path.  "why" tells us if this was a real syscall.
  */
@@ -409,6 +401,7 @@ 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
 
@@ -450,7 +443,8 @@ __sys_trace:
 	mov	scno, r0			@ syscall number (possibly new)
 	add	r1, sp, #S_R0 + S_OFF		@ pointer to regs
 	cmp	scno, #NR_syscalls		@ check upper syscall limit
-	ldmccia	r1, {r0 - r3}			@ have to reload r0 - r3
+	ldmccia	r1, {r0 - r6}			@ have to reload r0 - r6
+	stmccia	sp, {r4, r5}			@ and update the stack args
 	ldrcc	pc, [tbl, scno, lsl #2]		@ call sys_* routine
 	b	2b
 

arch/arm/kernel/ptrace.c

@@ -25,6 +25,7 @@
 #include <linux/regset.h>
 #include <linux/audit.h>
 #include <linux/tracehook.h>
+#include <linux/unistd.h>
 
 #include <asm/pgtable.h>
 #include <asm/traps.h>

arch/arm/kernel/signal.c

@@ -27,7 +27,6 @@
  */
 #define SWI_SYS_SIGRETURN	(0xef000000|(__NR_sigreturn)|(__NR_OABI_SYSCALL_BASE))
 #define SWI_SYS_RT_SIGRETURN	(0xef000000|(__NR_rt_sigreturn)|(__NR_OABI_SYSCALL_BASE))
-#define SWI_SYS_RESTART		(0xef000000|__NR_restart_syscall|__NR_OABI_SYSCALL_BASE)
 
 /*
  * With EABI, the syscall number has to be loaded into r7.
@@ -47,18 +46,6 @@ const unsigned long sigreturn_codes[7] = {
 	MOV_R7_NR_RT_SIGRETURN, SWI_SYS_RT_SIGRETURN, SWI_THUMB_RT_SIGRETURN,
 };
 
-/*
- * Either we support OABI only, or we have EABI with the OABI
- * compat layer enabled.  In the later case we don't know if
- * user space is EABI or not, and if not we must not clobber r7.
- * Always using the OABI syscall solves that issue and works for
- * all those cases.
- */
-const unsigned long syscall_restart_code[2] = {
-	SWI_SYS_RESTART,	/* swi	__NR_restart_syscall */
-	0xe49df004,		/* ldr	pc, [sp], #4 */
-};
-
 /*
  * atomically swap in the new signal mask, and wait for a signal.
  */
@@ -582,12 +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...
@@ -602,15 +590,15 @@ static void do_signal(struct pt_regs *regs, int syscall)
 		 * debugger will see the already changed PSW.
 		 */
 		switch (retval) {
+		case -ERESTART_RESTARTBLOCK:
+			restart -= 2;
 		case -ERESTARTNOHAND:
 		case -ERESTARTSYS:
 		case -ERESTARTNOINTR:
+			restart++;
 			regs->ARM_r0 = regs->ARM_ORIG_r0;
 			regs->ARM_pc = restart_addr;
 			break;
-		case -ERESTART_RESTARTBLOCK:
-			regs->ARM_r0 = -EINTR;
-			break;
 		}
 	}
 
@@ -619,14 +607,17 @@ 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 (retval == -ERESTARTNOHAND
+		if (unlikely(restart)) {
+			if (retval == -ERESTARTNOHAND ||
+			    retval == -ERESTART_RESTARTBLOCK
 			    || (retval == -ERESTARTSYS
 				&& !(ka.sa.sa_flags & SA_RESTART))) {
 				regs->ARM_r0 = -EINTR;
@@ -635,52 +626,43 @@ static void do_signal(struct pt_regs *regs, int syscall)
 		}
 
 		handle_signal(signr, &ka, &info, regs);
-		return;
-	}
-
-	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 == 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
-			}
-		}
+		return 0;
 	}
 
 	restore_saved_sigmask();
+	if (unlikely(restart))
+		regs->ARM_pc = continue_addr;
+	return restart;
 }
 
-asmlinkage void
-do_notify_resume(struct pt_regs *regs, unsigned int thread_flags, int syscall)
+asmlinkage int
+do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
 {
-	if (thread_flags & _TIF_SIGPENDING)
-		do_signal(regs, syscall);
-
-	if (thread_flags & _TIF_NOTIFY_RESUME) {
-		clear_thread_flag(TIF_NOTIFY_RESUME);
-		tracehook_notify_resume(regs);
-	}
+	do {
+		if (likely(thread_flags & _TIF_NEED_RESCHED)) {
+			schedule();
+		} else {
+			if (unlikely(!user_mode(regs)))
+				return 0;
+			local_irq_enable();
+			if (thread_flags & _TIF_SIGPENDING) {
+				int restart = do_signal(regs, syscall);
+				if (unlikely(restart)) {
+					/*
+					 * Restart without handlers.
+					 * Deal with it without leaving
+					 * the kernel space.
+					 */
+					return restart;
+				}
+				syscall = 0;
+			} else {
+				clear_thread_flag(TIF_NOTIFY_RESUME);
+				tracehook_notify_resume(regs);
+			}
+		}
+		local_irq_disable();
+		thread_flags = current_thread_info()->flags;
+	} while (thread_flags & _TIF_WORK_MASK);
+	return 0;
 }

arch/arm/kernel/signal.h

@@ -8,7 +8,5 @@
  * published by the Free Software Foundation.
  */
 #define KERN_SIGRETURN_CODE	(CONFIG_VECTORS_BASE + 0x00000500)
-#define KERN_RESTART_CODE	(KERN_SIGRETURN_CODE + sizeof(sigreturn_codes))
 
 extern const unsigned long sigreturn_codes[7];
-extern const unsigned long syscall_restart_code[2];

arch/arm/kernel/traps.c

@@ -844,8 +844,6 @@ void __init early_trap_init(void *vectors_base)
 	 */
 	memcpy((void *)(vectors + KERN_SIGRETURN_CODE - CONFIG_VECTORS_BASE),
 	       sigreturn_codes, sizeof(sigreturn_codes));
-	memcpy((void *)(vectors + KERN_RESTART_CODE - CONFIG_VECTORS_BASE),
-	       syscall_restart_code, sizeof(syscall_restart_code));
 
 	flush_icache_range(vectors, vectors + PAGE_SIZE);
 	modify_domain(DOMAIN_USER, DOMAIN_CLIENT);