Christophe Leroy <christophe.le...@c-s.fr> writes: > __get_datapage() is only a few instructions to retrieve the > address of the page where the kernel stores data to the VDSO. > > By inlining this function into its users, a bl/blr pair and > a mflr/mtlr pair is avoided, plus a few reg moves. > > The improvement is noticeable (about 55 nsec/call on an 8xx) > > vdsotest before the patch: > gettimeofday: vdso: 731 nsec/call > clock-gettime-realtime-coarse: vdso: 668 nsec/call > clock-gettime-monotonic-coarse: vdso: 745 nsec/call > > vdsotest after the patch: > gettimeofday: vdso: 677 nsec/call > clock-gettime-realtime-coarse: vdso: 613 nsec/call > clock-gettime-monotonic-coarse: vdso: 690 nsec/call > > Signed-off-by: Christophe Leroy <christophe.le...@c-s.fr>
This doesn't build with gcc 4.6.3: /linux/arch/powerpc/kernel/vdso32/gettimeofday.S: Assembler messages: /linux/arch/powerpc/kernel/vdso32/gettimeofday.S:41: Error: unsupported relocation against __kernel_datapage_offset /linux/arch/powerpc/kernel/vdso32/gettimeofday.S:86: Error: unsupported relocation against __kernel_datapage_offset /linux/arch/powerpc/kernel/vdso32/gettimeofday.S:213: Error: unsupported relocation against __kernel_datapage_offset /linux/arch/powerpc/kernel/vdso32/gettimeofday.S:247: Error: unsupported relocation against __kernel_datapage_offset make[4]: *** [arch/powerpc/kernel/vdso32/gettimeofday.o] Error 1 https://travis-ci.org/linuxppc/linux/jobs/614904530 cheers > --- > v3: define get_datapage macro in asm/vdso_datapage.h > --- > arch/powerpc/include/asm/vdso_datapage.h | 10 ++++++++++ > arch/powerpc/kernel/vdso32/cacheflush.S | 9 ++++----- > arch/powerpc/kernel/vdso32/datapage.S | 28 +++------------------------- > arch/powerpc/kernel/vdso32/gettimeofday.S | 12 +++++------- > 4 files changed, 22 insertions(+), 37 deletions(-) > > diff --git a/arch/powerpc/include/asm/vdso_datapage.h > b/arch/powerpc/include/asm/vdso_datapage.h > index 2ccb938d8544..da3d2de817f6 100644 > --- a/arch/powerpc/include/asm/vdso_datapage.h > +++ b/arch/powerpc/include/asm/vdso_datapage.h > @@ -116,6 +116,16 @@ struct vdso_data { > > extern struct vdso_data *vdso_data; > > +#else /* __ASSEMBLY__ */ > + > +.macro get_datapage ptr, tmp > + bcl 20, 31, .+4 > + mflr \ptr > + addi \ptr, \ptr, __kernel_datapage_offset - (.-4) > + lwz \tmp, 0(\ptr) > + add \ptr, \tmp, \ptr > +.endm > + > #endif /* __ASSEMBLY__ */ > > #endif /* __KERNEL__ */ > diff --git a/arch/powerpc/kernel/vdso32/cacheflush.S > b/arch/powerpc/kernel/vdso32/cacheflush.S > index 7f882e7b9f43..d178ec8c279d 100644 > --- a/arch/powerpc/kernel/vdso32/cacheflush.S > +++ b/arch/powerpc/kernel/vdso32/cacheflush.S > @@ -8,6 +8,7 @@ > #include <asm/processor.h> > #include <asm/ppc_asm.h> > #include <asm/vdso.h> > +#include <asm/vdso_datapage.h> > #include <asm/asm-offsets.h> > > .text > @@ -24,14 +25,12 @@ V_FUNCTION_BEGIN(__kernel_sync_dicache) > .cfi_startproc > mflr r12 > .cfi_register lr,r12 > - mr r11,r3 > - bl __get_datapage@local > + get_datapage r10, r0 > mtlr r12 > - mr r10,r3 > > lwz r7,CFG_DCACHE_BLOCKSZ(r10) > addi r5,r7,-1 > - andc r6,r11,r5 /* round low to line bdy */ > + andc r6,r3,r5 /* round low to line bdy */ > subf r8,r6,r4 /* compute length */ > add r8,r8,r5 /* ensure we get enough */ > lwz r9,CFG_DCACHE_LOGBLOCKSZ(r10) > @@ -48,7 +47,7 @@ V_FUNCTION_BEGIN(__kernel_sync_dicache) > > lwz r7,CFG_ICACHE_BLOCKSZ(r10) > addi r5,r7,-1 > - andc r6,r11,r5 /* round low to line bdy */ > + andc r6,r3,r5 /* round low to line bdy */ > subf r8,r6,r4 /* compute length */ > add r8,r8,r5 > lwz r9,CFG_ICACHE_LOGBLOCKSZ(r10) > diff --git a/arch/powerpc/kernel/vdso32/datapage.S > b/arch/powerpc/kernel/vdso32/datapage.S > index 6c7401bd284e..1095d818f94a 100644 > --- a/arch/powerpc/kernel/vdso32/datapage.S > +++ b/arch/powerpc/kernel/vdso32/datapage.S > @@ -10,35 +10,13 @@ > #include <asm/asm-offsets.h> > #include <asm/unistd.h> > #include <asm/vdso.h> > +#include <asm/vdso_datapage.h> > > .text > .global __kernel_datapage_offset; > __kernel_datapage_offset: > .long 0 > > -V_FUNCTION_BEGIN(__get_datapage) > - .cfi_startproc > - /* We don't want that exposed or overridable as we want other objects > - * to be able to bl directly to here > - */ > - .protected __get_datapage > - .hidden __get_datapage > - > - mflr r0 > - .cfi_register lr,r0 > - > - bcl 20,31,data_page_branch > -data_page_branch: > - mflr r3 > - mtlr r0 > - addi r3, r3, __kernel_datapage_offset-data_page_branch > - lwz r0,0(r3) > - .cfi_restore lr > - add r3,r0,r3 > - blr > - .cfi_endproc > -V_FUNCTION_END(__get_datapage) > - > /* > * void *__kernel_get_syscall_map(unsigned int *syscall_count) ; > * > @@ -53,7 +31,7 @@ V_FUNCTION_BEGIN(__kernel_get_syscall_map) > mflr r12 > .cfi_register lr,r12 > mr r4,r3 > - bl __get_datapage@local > + get_datapage r3, r0 > mtlr r12 > addi r3,r3,CFG_SYSCALL_MAP32 > cmpli cr0,r4,0 > @@ -75,7 +53,7 @@ V_FUNCTION_BEGIN(__kernel_get_tbfreq) > .cfi_startproc > mflr r12 > .cfi_register lr,r12 > - bl __get_datapage@local > + get_datapage r3, r0 > lwz r4,(CFG_TB_TICKS_PER_SEC + 4)(r3) > lwz r3,CFG_TB_TICKS_PER_SEC(r3) > mtlr r12 > diff --git a/arch/powerpc/kernel/vdso32/gettimeofday.S > b/arch/powerpc/kernel/vdso32/gettimeofday.S > index 355b537d327a..9867c7b9a25a 100644 > --- a/arch/powerpc/kernel/vdso32/gettimeofday.S > +++ b/arch/powerpc/kernel/vdso32/gettimeofday.S > @@ -9,6 +9,7 @@ > #include <asm/processor.h> > #include <asm/ppc_asm.h> > #include <asm/vdso.h> > +#include <asm/vdso_datapage.h> > #include <asm/asm-offsets.h> > #include <asm/unistd.h> > > @@ -35,8 +36,7 @@ V_FUNCTION_BEGIN(__kernel_gettimeofday) > > mr r10,r3 /* r10 saves tv */ > mr r11,r4 /* r11 saves tz */ > - bl __get_datapage@local /* get data page */ > - mr r9, r3 /* datapage ptr in r9 */ > + get_datapage r9, r0 > cmplwi r10,0 /* check if tv is NULL */ > beq 3f > lis r7,1000000@ha /* load up USEC_PER_SEC */ > @@ -82,8 +82,7 @@ V_FUNCTION_BEGIN(__kernel_clock_gettime) > mflr r12 /* r12 saves lr */ > .cfi_register lr,r12 > mr r11,r4 /* r11 saves tp */ > - bl __get_datapage@local /* get data page */ > - mr r9,r3 /* datapage ptr in r9 */ > + get_datapage r9, r0 > lis r7,NSEC_PER_SEC@h /* want nanoseconds */ > ori r7,r7,NSEC_PER_SEC@l > beq cr5, .Lcoarse_clocks > @@ -208,7 +207,7 @@ V_FUNCTION_BEGIN(__kernel_clock_getres) > > mflr r12 > .cfi_register lr,r12 > - bl __get_datapage@local /* get data page */ > + get_datapage r3, r0 > lwz r5, CLOCK_HRTIMER_RES(r3) > mtlr r12 > li r3,0 > @@ -242,8 +241,7 @@ V_FUNCTION_BEGIN(__kernel_time) > .cfi_register lr,r12 > > mr r11,r3 /* r11 holds t */ > - bl __get_datapage@local > - mr r9, r3 /* datapage ptr in r9 */ > + get_datapage r9, r0 > > lwz r3,STAMP_XTIME+TSPEC_TV_SEC(r9) > > -- > 2.13.3
