From 7586bf7286097cd47299c44192c30e01f0d55391 Mon Sep 17 00:00:00 2001 From: Vineet Gupta Date: Fri, 12 Apr 2013 12:18:25 +0530 Subject: [PATCH] ARC: [mm] optimise icache flush for kernel mappings 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 --- arch/arc/mm/cache_arc700.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) diff --git a/arch/arc/mm/cache_arc700.c b/arch/arc/mm/cache_arc700.c index a65c139..5651e7b 100644 --- a/arch/arc/mm/cache_arc700.c +++ b/arch/arc/mm/cache_arc700.c @@ -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; -- 2.7.4