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authorHuacai Chen <chenhc@lemote.com>2013-03-17 11:49:38 +0000
committerRalf Baechle <ralf@linux-mips.org>2013-05-08 01:19:06 +0200
commit8759934e2b6bdb3a08a81fc14a6588f3321719b1 (patch)
tree985985567d0691275692a2f8a4bd4bf64c60c0ce /arch/mips/mm
parent59b435d1ad48ac244058845e18586eb5719f7f99 (diff)
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 <chenhc@lemote.com> Signed-off-by: Hongbing Hu <huhb@lemote.com> Acked-by: David Daney <david.daney@cavium.com> Patchwork: http://patchwork.linux-mips.org/patch/4994/ Acked-by: John Crispin <blogic@openwrt.org>
Diffstat (limited to 'arch/mips/mm')
-rw-r--r--arch/mips/mm/page.c10
-rw-r--r--arch/mips/mm/tlbex.c10
2 files changed, 18 insertions, 2 deletions
diff --git a/arch/mips/mm/page.c b/arch/mips/mm/page.c
index a29fba55b53..4eb8dcfaf1c 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 820e6612d74..6bc28b4db31 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();
}
}