Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756094Ab3CQMuJ (ORCPT ); Sun, 17 Mar 2013 08:50:09 -0400 Received: from mail-pb0-f50.google.com ([209.85.160.50]:49029 "EHLO mail-pb0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750955Ab3CQMuF (ORCPT ); Sun, 17 Mar 2013 08:50:05 -0400 From: Huacai Chen To: Ralf Baechle Cc: linux-mips@linux-mips.org, linux-kernel@vger.kernel.org, Fuxin Zhang , Zhangjin Wu , Huacai Chen , Hongbing Hu Subject: [PATCH V2 01/02] MIPS: Build uasm-generated code only once to avoid CPU Hotplug problem Date: Sun, 17 Mar 2013 20:49:38 +0800 Message-Id: <1363524578-3765-1-git-send-email-chenhc@lemote.com> X-Mailer: git-send-email 1.7.7.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4855 Lines: 139 This and the next patch resolve memory corruption problems while CPU hotplug. Without these patches, memory corruption can triggered easily as below: On a quad-core MIPS platform, use "spawn" of UnixBench-5.1.3 (http:// code.google.com/p/byte-unixbench/) and a CPU hotplug script like this (hotplug.sh): while true; do echo 0 >/sys/devices/system/cpu/cpu1/online echo 0 >/sys/devices/system/cpu/cpu2/online echo 0 >/sys/devices/system/cpu/cpu3/online sleep 1 echo 1 >/sys/devices/system/cpu/cpu1/online echo 1 >/sys/devices/system/cpu/cpu2/online echo 1 >/sys/devices/system/cpu/cpu3/online sleep 1 done Run "hotplug.sh" and then run "spawn 10000", spawn will get segfault after a few minutes. This patch: Currently, clear_page()/copy_page() are generated by Micro-assembler dynamically. But they are unavailable until uasm_resolve_relocs() has finished because jump labels are illegal before that. Since these functions are shared by every CPU, we only call build_clear_page()/ build_copy_page() only once at boot time. Without this patch, programs will get random memory corruption (segmentation fault, bus error, etc.) while CPU Hotplug (e.g. one CPU is using clear_page() while another is generating it in cpu_cache_init()). For similar reasons we modify build_tlb_refill_handler()'s invocation. V2: 1, Rework the code to make CPU#0 can be online/offline. 2, Introduce cpu_has_local_ebase feature since some types of MIPS CPU need a per-CPU tlb_refill_handler(). Signed-off-by: Huacai Chen Signed-off-by: Hongbing Hu --- arch/mips/include/asm/cpu-features.h | 3 +++ .../asm/mach-loongson/cpu-feature-overrides.h | 1 + arch/mips/mm/page.c | 10 ++++++++++ arch/mips/mm/tlbex.c | 10 ++++++++-- 4 files changed, 22 insertions(+), 2 deletions(-) diff --git a/arch/mips/include/asm/cpu-features.h b/arch/mips/include/asm/cpu-features.h index 1a57e8b..e5ec8fc 100644 --- a/arch/mips/include/asm/cpu-features.h +++ b/arch/mips/include/asm/cpu-features.h @@ -113,6 +113,9 @@ #ifndef cpu_has_pindexed_dcache #define cpu_has_pindexed_dcache (cpu_data[0].dcache.flags & MIPS_CACHE_PINDEX) #endif +#ifndef cpu_has_local_ebase +#define cpu_has_local_ebase 1 +#endif /* * I-Cache snoops remote store. This only matters on SMP. Some multiprocessors diff --git a/arch/mips/include/asm/mach-loongson/cpu-feature-overrides.h b/arch/mips/include/asm/mach-loongson/cpu-feature-overrides.h index 75fd8c0..c0f3ef4 100644 --- a/arch/mips/include/asm/mach-loongson/cpu-feature-overrides.h +++ b/arch/mips/include/asm/mach-loongson/cpu-feature-overrides.h @@ -57,5 +57,6 @@ #define cpu_has_vint 0 #define cpu_has_vtag_icache 0 #define cpu_has_watch 1 +#define cpu_has_local_ebase 0 #endif /* __ASM_MACH_LOONGSON_CPU_FEATURE_OVERRIDES_H */ diff --git a/arch/mips/mm/page.c b/arch/mips/mm/page.c index a29fba5..4eb8dcf 100644 --- a/arch/mips/mm/page.c +++ b/arch/mips/mm/page.c @@ -247,6 +247,11 @@ void __cpuinit build_clear_page(void) struct uasm_label *l = labels; struct uasm_reloc *r = relocs; int i; + static atomic_t run_once = ATOMIC_INIT(0); + + if (atomic_xchg(&run_once, 1)) { + return; + } memset(labels, 0, sizeof(labels)); memset(relocs, 0, sizeof(relocs)); @@ -389,6 +394,11 @@ void __cpuinit build_copy_page(void) struct uasm_label *l = labels; struct uasm_reloc *r = relocs; int i; + static atomic_t run_once = ATOMIC_INIT(0); + + if (atomic_xchg(&run_once, 1)) { + return; + } memset(labels, 0, sizeof(labels)); memset(relocs, 0, sizeof(relocs)); diff --git a/arch/mips/mm/tlbex.c b/arch/mips/mm/tlbex.c index 820e661..6bc28b4 100644 --- a/arch/mips/mm/tlbex.c +++ b/arch/mips/mm/tlbex.c @@ -2162,8 +2162,11 @@ void __cpuinit build_tlb_refill_handler(void) case CPU_TX3922: case CPU_TX3927: #ifndef CONFIG_MIPS_PGD_C0_CONTEXT - build_r3000_tlb_refill_handler(); + if (cpu_has_local_ebase) + build_r3000_tlb_refill_handler(); if (!run_once) { + if (!cpu_has_local_ebase) + build_r3000_tlb_refill_handler(); build_r3000_tlb_load_handler(); build_r3000_tlb_store_handler(); build_r3000_tlb_modify_handler(); @@ -2192,9 +2195,12 @@ void __cpuinit build_tlb_refill_handler(void) build_r4000_tlb_load_handler(); build_r4000_tlb_store_handler(); build_r4000_tlb_modify_handler(); + if (!cpu_has_local_ebase) + build_r4000_tlb_refill_handler(); run_once++; } - build_r4000_tlb_refill_handler(); + if (cpu_has_local_ebase) + build_r4000_tlb_refill_handler(); } } -- 1.7.7.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/