From 8af8d72dc58e90dc945ca627b24968400e0f21b6 Mon Sep 17 00:00:00 2001 From: Christophe Leroy Date: Thu, 6 May 2021 13:27:31 +0000 Subject: [PATCH] powerpc/32s: Speed up likely path of kuap_update_sr() In most cases, kuap_update_sr() will update a single segment register. We know that first update will always be done, if there is no segment register to update at all, kuap_update_sr() is not called. Avoid recurring calculations and tests in that case. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/848f18d213b8341939add7302dc4ef80cc7a12e3.1620307636.git.christophe.leroy@csgroup.eu --- arch/powerpc/include/asm/book3s/32/kup.h | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/include/asm/book3s/32/kup.h b/arch/powerpc/include/asm/book3s/32/kup.h index 1670dfe9d4f10b..c1f7c2e625a656 100644 --- a/arch/powerpc/include/asm/book3s/32/kup.h +++ b/arch/powerpc/include/asm/book3s/32/kup.h @@ -15,11 +15,13 @@ static inline void kuap_update_sr(u32 sr, u32 addr, u32 end) { addr &= 0xf0000000; /* align addr to start of segment */ barrier(); /* make sure thread.kuap is updated before playing with SRs */ - while (addr < end) { + for (;;) { mtsr(sr, addr); + addr += 0x10000000; /* address of next segment */ + if (addr >= end) + break; sr += 0x111; /* next VSID */ sr &= 0xf0ffffff; /* clear VSID overflow */ - addr += 0x10000000; /* address of next segment */ } isync(); /* Context sync required after mtsr() */ }