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ARC: [mm] optimise icache flush for kernel mappings

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This change continues the theme from prev commit - this time icache
handling for kernel's own code modification (vmalloc: loadable modules,
breakpoints for kprobes/kgdb...)

flush_icache_range() calls the CDU icache helper with vaddr to enable
exact line invalidate.

For a true kernel-virtual mapping, the vaddr is actually virtual hence
valid as index into cache. For kprobes breakpoint however, the vaddr arg
is actually paddr - since that's how normal kernel is mapped in ARC
memory map.  This implies that CDU will use the same addr for
indexing as for tag match - which is fine since kernel code would only
have that "implicit" mapping and none other.

This should speed up module loading significantly - specially on default
ARC700 icache configurations (32k) which alias.

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
This commit is contained in:
Vineet Gupta 2013-04-12 12:18:25 +05:30
parent 24603fdd19
commit 7586bf7286
1 changed files with 10 additions and 4 deletions
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14
arch/arc/mm/cache_arc700.c
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@ -642,8 +642,8 @@ void dma_cache_wback(unsigned long start, unsigned long sz)
EXPORT_SYMBOL(dma_cache_wback);
/*
* This is API for making I/D Caches consistent when modifying code
* (loadable modules, kprobes, etc)
* This is API for making I/D Caches consistent when modifying
* kernel code (loadable modules, kprobes, kgdb...)
* This is called on insmod, with kernel virtual address for CODE of
* the module. ARC cache maintenance ops require PHY address thus we
* need to convert vmalloc addr to PHY addr
@ -673,7 +673,13 @@ void flush_icache_range(unsigned long kstart, unsigned long kend)
/* Case: Kernel Phy addr (0x8000_0000 onwards) */
if (likely(kstart > PAGE_OFFSET)) {
__ic_line_inv(kstart, kend - kstart);
/*
* The 2nd arg despite being paddr will be used to index icache
* This is OK since no alternate virtual mappings will exist
* given the callers for this case: kprobe/kgdb in built-in
* kernel code only.
*/
__ic_line_inv_vaddr(kstart, kstart, kend - kstart);
__dc_line_op(kstart, kend - kstart, OP_FLUSH);
return;
}
@ -694,7 +700,7 @@ void flush_icache_range(unsigned long kstart, unsigned long kend)
sz = min_t(unsigned int, tot_sz, PAGE_SIZE - off);
local_irq_save(flags);
__dc_line_op(phy, sz, OP_FLUSH);
__ic_line_inv(phy, sz);
__ic_line_inv_vaddr(phy, kstart, sz);
local_irq_restore(flags);
kstart += sz;
tot_sz -= sz;