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MIPS: Check TLB before handle_ri_rdhwr() for Loongson-3 

Loongson-3's micro TLB (ITLB) is not strictly a subset of JTLB. That
means: when a JTLB entry is replaced by hardware, there may be an old
valid entry exists in ITLB. So, a TLB miss exception may occur while
handle_ri_rdhwr() is running because it try to access EPC's content.
However, handle_ri_rdhwr() doesn't clear EXL, which makes a TLB Refill
exception be treated as a TLB Invalid exception and tlbp may fail. In
this case, if FTLB (which is usually set-associative instead of set-
associative) is enabled, a tlbp failure will cause an invalid tlbwi,
which will hang the whole system.

This patch rename handle_ri_rdhwr_vivt to handle_ri_rdhwr_tlbp and use
it for Loongson-3. It try to solve the same problem described as below,
but more straightforwards.

https://patchwork.linux-mips.org/patch/12591/

I think Loongson-2 has the same problem, but it has no FTLB, so we just
keep it as is.

Signed-off-by: Huacai Chen <chenhc@lemote.com>
Cc: Rui Wang <wangr@lemote.com>
Cc: John Crispin <john@phrozen.org>
Cc: Steven J . Hill <Steven.Hill@caviumnetworks.com>
Cc: Fuxin Zhang <zhangfx@lemote.com>
Cc: Zhangjin Wu <wuzhangjin@gmail.com>
Cc: Huacai Chen <chenhc@lemote.com>
Cc: linux-mips@linux-mips.org
Cc: stable@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/15753/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
Huacai Chen 2017-03-16 21:00:26 +08:00 committed by Ralf Baechle
parent 033cffeedb
commit 5a34133167
2 changed files with 15 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
arch/mips/kernel/genex.S
View File

@ -519,7 +519,7 @@ NESTED(nmi_handler, PT_SIZE, sp)
BUILD_HANDLER reserved reserved sti verbose /* others */
.align 5
LEAF(handle_ri_rdhwr_vivt)
LEAF(handle_ri_rdhwr_tlbp)
.set push
.set noat
.set noreorder
@ -538,7 +538,7 @@ NESTED(nmi_handler, PT_SIZE, sp)
.set pop
bltz k1, handle_ri /* slow path */
/* fall thru */
END(handle_ri_rdhwr_vivt)
END(handle_ri_rdhwr_tlbp)
LEAF(handle_ri_rdhwr)
.set push

17
arch/mips/kernel/traps.c
View File

@ -83,7 +83,7 @@ extern asmlinkage void handle_dbe(void);
extern asmlinkage void handle_sys(void);
extern asmlinkage void handle_bp(void);
extern asmlinkage void handle_ri(void);
extern asmlinkage void handle_ri_rdhwr_vivt(void);
extern asmlinkage void handle_ri_rdhwr_tlbp(void);
extern asmlinkage void handle_ri_rdhwr(void);
extern asmlinkage void handle_cpu(void);
extern asmlinkage void handle_ov(void);
@ -2408,9 +2408,18 @@ void __init trap_init(void)
set_except_vector(EXCCODE_SYS, handle_sys);
set_except_vector(EXCCODE_BP, handle_bp);
set_except_vector(EXCCODE_RI, rdhwr_noopt ? handle_ri :
(cpu_has_vtag_icache ?
handle_ri_rdhwr_vivt : handle_ri_rdhwr));
if (rdhwr_noopt)
set_except_vector(EXCCODE_RI, handle_ri);
else {
if (cpu_has_vtag_icache)
set_except_vector(EXCCODE_RI, handle_ri_rdhwr_tlbp);
else if (current_cpu_type() == CPU_LOONGSON3)
set_except_vector(EXCCODE_RI, handle_ri_rdhwr_tlbp);
else
set_except_vector(EXCCODE_RI, handle_ri_rdhwr);
}
set_except_vector(EXCCODE_CPU, handle_cpu);
set_except_vector(EXCCODE_OV, handle_ov);
set_except_vector(EXCCODE_TR, handle_tr);