4.9-stable review patch. If anyone has any objections, please let me know.
------------------ From: Huacai Chen <[email protected]> commit 5a34133167dce36666ea054e30a561b7f4413b7f upstream. 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 <[email protected]> Cc: Rui Wang <[email protected]> Cc: John Crispin <[email protected]> Cc: Steven J . Hill <[email protected]> Cc: Fuxin Zhang <[email protected]> Cc: Zhangjin Wu <[email protected]> Cc: Huacai Chen <[email protected]> Cc: [email protected] Patchwork: https://patchwork.linux-mips.org/patch/15753/ Signed-off-by: Ralf Baechle <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- arch/mips/kernel/genex.S | 4 ++-- arch/mips/kernel/traps.c | 17 +++++++++++++---- 2 files changed, 15 insertions(+), 6 deletions(-) --- a/arch/mips/kernel/genex.S +++ b/arch/mips/kernel/genex.S @@ -448,7 +448,7 @@ 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 @@ -467,7 +467,7 @@ 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 --- a/arch/mips/kernel/traps.c +++ b/arch/mips/kernel/traps.c @@ -81,7 +81,7 @@ 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); @@ -2352,9 +2352,18 @@ 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);
