From: David Daney Date: Tue, 6 Jan 2015 18:42:23 +0000 (-0800) Subject: MIPS: Fix C0_Pagegrain[IEC] support. X-Git-Tag: firefly_0821_release~176^2~2420^2~5 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=9ead8632bbf454cfc709b6205dc9cd8582fb0d64;p=firefly-linux-kernel-4.4.55.git MIPS: Fix C0_Pagegrain[IEC] support. The following commits: 5890f70f15c52d (MIPS: Use dedicated exception handler if CPU supports RI/XI exceptions) 6575b1d4173eae (MIPS: kernel: cpu-probe: Detect unique RI/XI exceptions) break the kernel for *all* existing MIPS CPUs that implement the CP0_PageGrain[IEC] bit. They cause the TLB exception handlers to be generated without the legacy execute-inhibit handling, but never set the CP0_PageGrain[IEC] bit to activate the use of dedicated exception vectors for execute-inhibit exceptions. The result is that upon detection of an execute-inhibit violation, we loop forever in the TLB exception handlers instead of sending SIGSEGV to the task. If we are generating TLB exception handlers expecting separate vectors, we must also enable the CP0_PageGrain[IEC] feature. The bug was introduced in kernel version 3.17. Signed-off-by: David Daney Cc: Cc: Leonid Yegoshin Cc: linux-mips@linux-mips.org Patchwork: http://patchwork.linux-mips.org/patch/8880/ Signed-off-by: Ralf Baechle --- diff --git a/arch/mips/mm/tlb-r4k.c b/arch/mips/mm/tlb-r4k.c index e90b2e899291..30639a6e9b8c 100644 --- a/arch/mips/mm/tlb-r4k.c +++ b/arch/mips/mm/tlb-r4k.c @@ -489,6 +489,8 @@ static void r4k_tlb_configure(void) #ifdef CONFIG_64BIT pg |= PG_ELPA; #endif + if (cpu_has_rixiex) + pg |= PG_IEC; write_c0_pagegrain(pg); }