| Date | Mon, 6 Aug 2012 12:12:24 +0100 | From | Russell King - ARM Linux <> | Subject | Re: [PATCH 01/22] ARM: add mechanism for late code patching |
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On Tue, Jul 31, 2012 at 07:04:37PM -0400, Cyril Chemparathy wrote: > +static void __init init_patch_kernel(void) > +{ > + const void *start = &__patch_table_begin; > + const void *end = &__patch_table_end; > + > + BUG_ON(patch_kernel(start, end - start)); > + flush_icache_range(init_mm.start_code, init_mm.end_code);
Err. You are asking the kernel to flush every single cache line manually throughout the kernel code. That's a flush every 32-bytes over maybe a few megabytes of address space.
This is one of the reasons we do the patching in assembly code before the caches are enabled - so we don't have to worry about the interaction with the CPU caches, which for this kind of application would be very expensive.
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