[PATCH] ARM: Sort exception table at compile time

On 07/30/12 15:38, Stephen Boyd wrote:

On 07/30/12 14:56, Russell King - ARM Linux wrote:

quoted

On Mon, Jul 30, 2012 at 02:30:03PM -0700, Stephen Boyd wrote:

quoted

Add the ARM machine identifier to sortextable and select the
config option so that we can sort the exception table at compile
time. sortextable relies on a section named __ex_table existing
in the vmlinux, but ARM's linker script places the exception
table in the data section. Give the exception table its own
section so that sortextable can find it.

This allows us to skip the runtime sorting step during boot.

Signed-off-by: Stephen Boyd <redacted>
Cc: David Daney <redacted>
---

I can't find any information on why the exception table lives in the data
section. If there's a good reason for that, I'll look into changing
sortextable to look for the __start___ex_table symbol.

Be careful about the placement of this, especially with XIP.

Thanks for the hint. I'm unfamiliar with how XIP works so I'll take a
closer look there.

Ok. It looks like the exception table is placed in the data section so
that XIP kernels can boot up and sort the exception table (otherwise the
exception table would be in read-only flash). Now that the exception
table is sorted at compile time, we should be able to place the
exception table in the rodata area, essentially placing the table in the
non-volatile storage on XIP kernels.

I propose we move the exception table right after the rodata. Other
arches (x86/mips) may actually want to put the exception table into the
rodata, but that looks like a larger change.

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