Merge branch 'for-linus' of git://ftp.arm.linux.org.uk/~rmk/linux-arm

Pull ARM updates from Russell King:
 "In this ARM merge, we remove more lines than we add.  Changes include:

   - Enable imprecise aborts early, so that bus errors aren't masked
     until later in the boot.  This has the side effect that boot
     loaders which provoke these aborts can cause the kernel to crash
     early in boot, so we install a handler to report this event around
     the site where these are enabled.

   - Remove the buggy but impossible to enable cmpxchg syscall code.

   - Add unwinding annotations to some assembly code.

   - Add support for atomic half-word exchange for ARMv6k+.

   - Reduce ioremap() alignment for SMP/LPAE cases where we don't need
     the large alignment.

   - Addition of an "optimal" 3G configuration for systems with 1G of
     RAM.

   - Increase vmalloc space by 128M.

   - Constify some SMP operations structures, which have never been
     writable.

   - Improve ARMs dma_mmap() support for mapping DMA coherent mappings
     into userspace.

   - Fix to the NMI backtrace code in the IPI case on ARM where the
     failing CPU gets stuck for 10s waiting for its own IPI to be
     delivered.

   - Removal of legacy PM support from the AMBA bus driver.

   - Another fix for the previous fix of vdsomunge"

* 'for-linus' of git://ftp.arm.linux.org.uk/~rmk/linux-arm: (23 commits)
  ARM: 8449/1: fix bug in vdsomunge swab32 macro
  arm: add missing of_node_put
  ARM: 8447/1: catch pending imprecise abort on unmask
  ARM: 8446/1: amba: Remove unused callbacks for legacy system PM
  ARM: 8443/1: Adding support for atomic half word exchange
  ARM: clean up TWD after previous patch
  ARM: 8441/2: twd: Don't set CLOCK_EVT_FEAT_C3STOP unconditionally
  ARM: 8440/1: remove obsolete documentation
  ARM: make highpte an expert option
  ARM: 8433/1: add a VMSPLIT_3G_OPT config option
  ARM: 8439/1: Fix backtrace generation when IPI is masked
  ARM: 8428/1: kgdb: Fix registers on sleeping tasks
  ARM: 8427/1: dma-mapping: add support for offset parameter in dma_mmap()
  ARM: 8426/1: dma-mapping: add missing range check in dma_mmap()
  ARM: remove user cmpxchg syscall
  ARM: 8438/1: Add unwinding to __clear_user_std()
  ARM: 8436/1: hw_breakpoint: remove unnecessary header
  ARM: 8434/2: Revert "7655/1: smp_twd: make twd_local_timer_of_register() no-op for nosmp"
  ARM: 8432/1: move VMALLOC_END from 0xff000000 to 0xff800000
  ARM: 8430/1: use default ioremap alignment for SMP or LPAE
  ...

1 files changed, 10 insertions, 1 deletions

diff --git a/lib/nmi_backtrace.c b/lib/nmi_backtrace.c
index 88d3d32e5923..6019c53c669e 100644
--- a/lib/nmi_backtrace.c
+++ b/lib/nmi_backtrace.c
@@ -43,6 +43,12 @@ static void print_seq_line(struct nmi_seq_buf *s, int start, int end)
 	printk("%.*s", (end - start) + 1, buf);
 }
 
+/*
+ * When raise() is called it will be is passed a pointer to the
+ * backtrace_mask. Architectures that call nmi_cpu_backtrace()
+ * directly from their raise() functions may rely on the mask
+ * they are passed being updated as a side effect of this call.
+ */
 void nmi_trigger_all_cpu_backtrace(bool include_self,
 				   void (*raise)(cpumask_t *mask))
 {
@@ -149,7 +155,10 @@ bool nmi_cpu_backtrace(struct pt_regs *regs)
 		/* Replace printk to write into the NMI seq */
 		this_cpu_write(printk_func, nmi_vprintk);
 		pr_warn("NMI backtrace for cpu %d\n", cpu);
-		show_regs(regs);
+		if (regs)
+			show_regs(regs);
+		else
+			dump_stack();
 		this_cpu_write(printk_func, printk_func_save);
 
 		cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask));