Commit 625a6492 authored Apr 09, 2014 by Matt Wagantall

ARM: Don't dump vmalloc addresses with show_data()

Commit a744f794 ("ARM: Don't dump ioremapped memory with show_data()")
attempted to have show_data() return early if an ioremapped address
was passed for dumping. Unfortunately, this does not work in general
since find_vm_area() will only return an area pointer if it is passed
the starting address of the area.

Since no API presently exists to find the start of a VM area given
an address within that area, simplify show_data() to skip dumping
all vmalloc addresses rather than just ioremapped addresses. Other
non-ioremapped vmalloc addresses are not frequently necessary for
debugging anyway, so the impact of this trade-off should be small.

The motivation for this change is the same as before. For stability
reasons, we do not want to dump addresses corresponding to memory-
mapped peripherals that may be unclocked or otherwise inaccessible.

Change-Id: I1c5ac716926b5b573f83a16896acbe257e99bf12
Signed-off-by: Matt Wagantall <mattw@codeaurora.org>

parent ea19bfb9

arch/arm/kernel/process.c

+5 −8

Original line number	Diff line number	Diff line
		@@ -321,16 +321,13 @@ static void show_data(unsigned long addr, int nbytes, const char *name)
		u32 *p;

		/*
		* don't attempt to dump non-kernel addresses or
		* values that are probably just small negative numbers
		* don't attempt to dump non-kernel addresses, values that are probably
		* just small negative numbers, or vmalloc addresses that may point to
		* memory-mapped peripherals
		*/
		if (addr < PAGE_OFFSET \|\| addr > -256UL)
		if (addr < PAGE_OFFSET \|\| addr > -256UL \|\|
		is_vmalloc_addr((void *)addr))
		return;
		if (is_vmalloc_addr((void *)addr)) {
		struct vm_struct area = find_vm_area((void )addr);
		if (area && area->flags & VM_IOREMAP)
		return;
		}

		printk("\n%s: %#lx:\n", name, addr);