From c195e079e9dd00ffeb274965737280ca6d10ff70 Mon Sep 17 00:00:00 2001 From: James Hogan Date: Thu, 1 Sep 2016 17:30:08 +0100 Subject: [PATCH] MIPS: traps: Convert ebase to KSEG0 When allocating boot memory for the exception vector when vectored interrupts (vint) or vectored external interrupt controllers (veic) are enabled, try to ensure that the virtual address resides in KSeg0 (and WARN should that not be possible). This will be helpful on MIPS64 cores supporting the CP0_EBase Write Gate (WG) bit once we start using the WG bit to write the full ebase into CP0_EBase, as we ideally need to avoid hitting the architecturally poorly defined exception base for Cache Errors when CP0_EBase is in XKPhys. An exception is made for Enhanced Virtual Addressing (EVA) kernels which allow segments to be rearranged and to become uncached during cache error handling, making it valid for ebase to be elsewhere. Signed-off-by: James Hogan Cc: Matt Redfearn Cc: Leonid Yegoshin Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/14149/ Signed-off-by: Ralf Baechle --- arch/mips/kernel/traps.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c index 4b60fb53b604..edc0c3d8e386 100644 --- a/arch/mips/kernel/traps.c +++ b/arch/mips/kernel/traps.c @@ -2210,8 +2210,25 @@ void __init trap_init(void) if (cpu_has_veic || cpu_has_vint) { unsigned long size = 0x200 + VECTORSPACING*64; + phys_addr_t ebase_pa; + ebase = (unsigned long) __alloc_bootmem(size, 1 << fls(size), 0); + + /* + * Try to ensure ebase resides in KSeg0 if possible. + * + * It shouldn't generally be in XKPhys on MIPS64 to avoid + * hitting a poorly defined exception base for Cache Errors. + * The allocation is likely to be in the low 512MB of physical, + * in which case we should be able to convert to KSeg0. + * + * EVA is special though as it allows segments to be rearranged + * and to become uncached during cache error handling. + */ + ebase_pa = __pa(ebase); + if (!IS_ENABLED(CONFIG_EVA) && !WARN_ON(ebase_pa >= 0x20000000)) + ebase = CKSEG0ADDR(ebase_pa); } else { ebase = CAC_BASE; -- 2.20.1