| Message ID | 9dcad7b2c05a397a97cc1cab211b6cf0f09a9900.1442939410.git.christophe.leroy@c-s.fr (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Scott Wood |
| Headers | show |
Hi Christophe Really nice patchset! On Tue, 2015-09-22 at 18:51 +0200, Christophe Leroy wrote: > clear_pages() is never used, and PPC32 is the only architecture > (still) having this function. Neither PPC64 nor any other > architecture has it. > > This patch removes clear_page() and move clear_page() function > inline (same as PPC64) as it only is a few isns > > Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> > --- > No change in v2 > > arch/powerpc/include/asm/page_32.h | 17 ++++++++++++++--- > arch/powerpc/kernel/misc_32.S | 16 ---------------- > arch/powerpc/kernel/ppc_ksyms_32.c | 1 - > 3 files changed, 14 insertions(+), 20 deletions(-) > > diff --git a/arch/powerpc/include/asm/page_32.h b/arch/powerpc/include/asm/page_32.h > index 68d73b2..6a8e179 100644 > --- a/arch/powerpc/include/asm/page_32.h > +++ b/arch/powerpc/include/asm/page_32.h > @@ -1,6 +1,8 @@ > #ifndef _ASM_POWERPC_PAGE_32_H > #define _ASM_POWERPC_PAGE_32_H > > +#include <asm/cache.h> > + > #if defined(CONFIG_PHYSICAL_ALIGN) && (CONFIG_PHYSICAL_START != 0) > #if (CONFIG_PHYSICAL_START % CONFIG_PHYSICAL_ALIGN) != 0 > #error "CONFIG_PHYSICAL_START must be a multiple of CONFIG_PHYSICAL_ALIGN" > @@ -36,9 +38,18 @@ typedef unsigned long long pte_basic_t; > typedef unsigned long pte_basic_t; > #endif > > -struct page; > -extern void clear_pages(void *page, int order); > -static inline void clear_page(void *page) { clear_pages(page, 0); } > +/* > + * Clear page using the dcbz instruction, which doesn't cause any > + * memory traffic (except to write out any cache lines which get > + * displaced). This only works on cacheable memory. > + */ > +static inline void clear_page(void *addr) > +{ > + unsigned int i; > + > + for (i = 0; i < PAGE_SIZE / L1_CACHE_BYTES; i++, addr += L1_CACHE_BYTES) > + dcbz(addr); > +} Does gcc manage to transform this into efficient asm? Otherwise you could help gcc by using do { .. } while(--i); instead.
On Tue, Sep 22, 2015 at 06:51:09PM +0200, Christophe Leroy wrote: > clear_pages() is never used, and PPC32 is the only architecture > (still) having this function. Neither PPC64 nor any other > architecture has it. It is used, by clear_page(). > This patch removes clear_page() and move clear_page() function > inline (same as PPC64) as it only is a few isns It removes clear_pages(), not clear_page(). -Scott
diff --git a/arch/powerpc/include/asm/page_32.h b/arch/powerpc/include/asm/page_32.h index 68d73b2..6a8e179 100644 --- a/arch/powerpc/include/asm/page_32.h +++ b/arch/powerpc/include/asm/page_32.h @@ -1,6 +1,8 @@ #ifndef _ASM_POWERPC_PAGE_32_H #define _ASM_POWERPC_PAGE_32_H +#include <asm/cache.h> + #if defined(CONFIG_PHYSICAL_ALIGN) && (CONFIG_PHYSICAL_START != 0) #if (CONFIG_PHYSICAL_START % CONFIG_PHYSICAL_ALIGN) != 0 #error "CONFIG_PHYSICAL_START must be a multiple of CONFIG_PHYSICAL_ALIGN" @@ -36,9 +38,18 @@ typedef unsigned long long pte_basic_t; typedef unsigned long pte_basic_t; #endif -struct page; -extern void clear_pages(void *page, int order); -static inline void clear_page(void *page) { clear_pages(page, 0); } +/* + * Clear page using the dcbz instruction, which doesn't cause any + * memory traffic (except to write out any cache lines which get + * displaced). This only works on cacheable memory. + */ +static inline void clear_page(void *addr) +{ + unsigned int i; + + for (i = 0; i < PAGE_SIZE / L1_CACHE_BYTES; i++, addr += L1_CACHE_BYTES) + dcbz(addr); +} extern void copy_page(void *to, void *from); #include <asm-generic/getorder.h> diff --git a/arch/powerpc/kernel/misc_32.S b/arch/powerpc/kernel/misc_32.S index 72fd7a7..ce3ca08 100644 --- a/arch/powerpc/kernel/misc_32.S +++ b/arch/powerpc/kernel/misc_32.S @@ -517,22 +517,6 @@ END_FTR_SECTION_IFSET(CPU_FTR_COHERENT_ICACHE) #endif /* CONFIG_BOOKE */ /* - * Clear pages using the dcbz instruction, which doesn't cause any - * memory traffic (except to write out any cache lines which get - * displaced). This only works on cacheable memory. - * - * void clear_pages(void *page, int order) ; - */ -_GLOBAL(clear_pages) - li r0,PAGE_SIZE/L1_CACHE_BYTES - slw r0,r0,r4 - mtctr r0 -1: dcbz 0,r3 - addi r3,r3,L1_CACHE_BYTES - bdnz 1b - blr - -/* * Copy a whole page. We use the dcbz instruction on the destination * to reduce memory traffic (it eliminates the unnecessary reads of * the destination into cache). This requires that the destination diff --git a/arch/powerpc/kernel/ppc_ksyms_32.c b/arch/powerpc/kernel/ppc_ksyms_32.c index 30ddd8a..2bfaafe 100644 --- a/arch/powerpc/kernel/ppc_ksyms_32.c +++ b/arch/powerpc/kernel/ppc_ksyms_32.c @@ -10,7 +10,6 @@ #include <asm/pgtable.h> #include <asm/dcr.h> -EXPORT_SYMBOL(clear_pages); EXPORT_SYMBOL(ISA_DMA_THRESHOLD); EXPORT_SYMBOL(DMA_MODE_READ); EXPORT_SYMBOL(DMA_MODE_WRITE);
clear_pages() is never used, and PPC32 is the only architecture (still) having this function. Neither PPC64 nor any other architecture has it. This patch removes clear_page() and move clear_page() function inline (same as PPC64) as it only is a few isns Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> --- No change in v2 arch/powerpc/include/asm/page_32.h | 17 ++++++++++++++--- arch/powerpc/kernel/misc_32.S | 16 ---------------- arch/powerpc/kernel/ppc_ksyms_32.c | 1 - 3 files changed, 14 insertions(+), 20 deletions(-)