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""

5 files changed, 58 insertions, 85 deletions

diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index 49d9f9305247..978eac57e04a 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/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
 
diff --git a/arch/arm/kernel/ptrace.c b/arch/arm/kernel/ptrace.c
index dab711e6e1ca..3e0fc5f7ed4b 100644
--- a/arch/arm/kernel/ptrace.c
+++ b/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>
diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index 536c5d6b340b..f27789e4e38a 100644
--- a/arch/arm/kernel/signal.c
+++ b/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.
@@ -48,18 +47,6 @@ const unsigned long sigreturn_codes[7] = {
 };
 
 /*
- * 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.
  */
 asmlinkage int sys_sigsuspend(int restart, unsigned long oldmask, old_sigset_t mask)
@@ -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;
+                return 0;