Re: [PATCH v5] ARM: Use generic BUG() handler

From: Stephen Boyd
Date: Tue Aug 09 2011 - 18:16:12 EST

On 07/29/2011 12:56 AM, Simon Glass wrote:
> From: Simon Glass <sjg@xxxxxxxxxx>
> ARM uses its own BUG() handler which makes its output slightly different
> from other archtectures.
> One of the problems is that the ARM implementation doesn't report the function
> with the BUG() in it, but always reports the PC being in __bug(). The generic
> implementation doesn't have this problem.
> Currently we get something like:
> kernel BUG at fs/proc/breakme.c:35!
> Unable to handle kernel NULL pointer dereference at virtual address 00000000
> ...
> PC is at __bug+0x20/0x2c
> With this patch it displays:
> kernel BUG at fs/proc/breakme.c:35!
> Internal error: Oops - undefined instruction: 0 [#1] PREEMPT SMP
> ...
> PC is at write_breakme+0xd0/0x1b4
> This implementation uses an undefined instruction to implement BUG, and sets up
> a bug table containing the relevant information. Many versions of gcc do not
> support %c properly for ARM (inserting a # when they shouldn't) so we work
> around this using distasteful macro magic.
> v1: Initial version to replace existing ARM BUG() implementation with something
> more similar to other architectures.
> v2: Add Thumb support, remove backtrace whitespace output changes. Change to
> use macros instead of requiring the asm %d flag to work (thanks to
> Dave Martin <dave.martin@xxxxxxxxxx>)
> v3: Remove old BUG() implementation in favor of this one.
> Remove the Backtrace: message (will submit this separately).
> Use ARM_EXIT_KEEP() so that some architectures can dump exit text at link time
> thanks to Stephen Boyd <sboyd@xxxxxxxxxxxxxx> (although since we always
> define GENERIC_BUG this might be academic.)
> Rebase to linux-2.6.git master.
> v4: Allow BUGS in modules (these were not reported correctly in v3)
> (thanks to Stephen Boyd <sboyd@xxxxxxxxxxxxxx> for suggesting that.)
> Remove __bug() as this is no longer needed.
> v5: Add %progbits as the section flags.

Tested-by: Stephen Boyd <sboyd@xxxxxxxxxxxxxx>

> Signed-off-by: Simon Glass <sjg@xxxxxxxxxxxx>
> ---

Can you update the patch in the patch tracker? It would be great to see
this in the next merge window.

Sent by an employee of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at