From: Christophe Leroy <christophe.leroy@c-s.fr> To: Benjamin Herrenschmidt <benh@kernel.crashing.org>, Paul Mackerras <paulus@samba.org>, Michael Ellerman <mpe@ellerman.id.au>, nathanl@linux.ibm.com, arnd@arndb.de, tglx@linutronix.de, vincenzo.frascino@arm.com, luto@kernel.org Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org, x86@kernel.org Subject: [RFC PATCH v4 06/11] powerpc/vdso: provide inline alternative to __get_datapage() Date: Thu, 16 Jan 2020 17:58:30 +0000 (UTC) Message-ID: <2e730f4e6ef77be2d5bfc38273d8a622e2cb4f97.1579196675.git.christophe.leroy@c-s.fr> (raw) In-Reply-To: <cover.1579196675.git.christophe.leroy@c-s.fr> __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) With current __get_datapage() function: gettimeofday: vdso: 731 nsec/call clock-gettime-realtime-coarse: vdso: 668 nsec/call clock-gettime-monotonic-coarse: vdso: 745 nsec/call Using the __get_datapage macro provided by this 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.leroy@c-s.fr> --- arch/powerpc/include/asm/vdso_datapage.h | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/arch/powerpc/include/asm/vdso_datapage.h b/arch/powerpc/include/asm/vdso_datapage.h index 4d7965bf369e..7342cc0c1ae4 100644 --- a/arch/powerpc/include/asm/vdso_datapage.h +++ b/arch/powerpc/include/asm/vdso_datapage.h @@ -105,6 +105,17 @@ struct vdso_arch_data { extern struct vdso_arch_data *vdso_data; +#else /* __ASSEMBLY__ */ + +.macro get_datapage ptr, offset=0 + bcl 20, 31, .+4 + mflr \ptr +#if CONFIG_PPC_PAGE_SHIFT > 14 + addis \ptr, \ptr, (_vdso_datapage + \offset - (.-4))@ha +#endif + addi \ptr, \ptr, (_vdso_datapage + \offset - (.-4))@l +.endm + #endif /* __ASSEMBLY__ */ #endif /* __KERNEL__ */ -- 2.13.3
next prev parent reply index Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-01-16 17:58 [RFC PATCH v4 00/11] powerpc: switch VDSO to C implementation Christophe Leroy 2020-01-16 17:58 ` [RFC PATCH v4 01/11] powerpc/64: Don't provide time functions in compat VDSO32 Christophe Leroy 2020-01-16 17:58 ` [RFC PATCH v4 02/11] powerpc/vdso: Switch VDSO to generic C implementation Christophe Leroy 2020-01-16 17:58 ` [RFC PATCH v4 03/11] lib: vdso: only read hrtimer_res when needed in __cvdso_clock_getres() Christophe Leroy 2020-01-16 17:58 ` [RFC PATCH v4 04/11] powerpc/vdso: simplify __get_datapage() Christophe Leroy 2020-01-16 17:58 ` [RFC PATCH v4 05/11] lib: vdso: allow arches to provide vdso data pointer Christophe Leroy 2020-01-16 17:58 ` Christophe Leroy [this message] 2020-01-16 17:58 ` [RFC PATCH v4 07/11] powerpc/vdso: provide vdso data pointer from the ASM caller Christophe Leroy 2020-01-16 17:58 ` [RFC PATCH v4 08/11] lib: vdso: allow fixed clock mode Christophe Leroy 2020-01-16 20:13 ` Thomas Gleixner 2020-01-16 20:19 ` Andy Lutomirski 2020-01-16 21:07 ` Thomas Gleixner 2020-01-16 17:58 ` [RFC PATCH v4 09/11] powerpc/vdso: override __arch_vdso_capable() Christophe Leroy 2020-01-16 17:58 ` [RFC PATCH v4 10/11] lib: vdso: Allow arches to override the ns shift operation Christophe Leroy 2020-01-16 19:47 ` Andy Lutomirski 2020-01-16 19:57 ` Thomas Gleixner 2020-01-16 20:20 ` Andy Lutomirski 2020-01-29 7:14 ` Thomas Gleixner 2020-01-29 7:26 ` Christophe Leroy 2020-01-16 17:58 ` [RFC PATCH v4 11/11] powerpc/32: provide vdso_shift_ns() Christophe Leroy 2020-01-17 8:58 ` [RFC PATCH v4 00/11] powerpc: switch VDSO to C implementation Segher Boessenkool 2020-01-17 9:26 ` Christophe Leroy 2020-01-20 14:56 ` Christophe Leroy 2020-01-20 15:19 ` Segher Boessenkool 2020-01-20 17:08 ` Christophe Leroy 2020-01-20 17:27 ` Segher Boessenkool
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