From 8759934e2b6bdb3a08a81fc14a6588f3321719b1 Mon Sep 17 00:00:00 2001 From: Huacai Chen Date: Sun, 17 Mar 2013 11:49:38 +0000 Subject: [PATCH] MIPS: Build uasm-generated code only once to avoid CPU Hotplug problem 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 Acked-by: David Daney Patchwork: http://patchwork.linux-mips.org/patch/4994/ Acked-by: John Crispin --- arch/mips/include/asm/cpu-features.h | 3 +++ .../include/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 1a57e8b4d092..e5ec8fcd8afa 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 75fd8c0f986e..c0f3ef45c2c1 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 a29fba55b53e..4eb8dcfaf1ce 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 820e6612d744..6bc28b4db31d 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(); } }