1 files changed, 157 insertions, 0 deletions

diff --git a/arch/mips/mm/cex-sb1.S b/arch/mips/mm/cex-sb1.S
new file mode 100644
index 000000000..85c6e6a40
--- /dev/null
+++ b/arch/mips/mm/cex-sb1.S
@@ -0,0 +1,157 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2001,2002,2003 Broadcom Corporation
+ */
+
+#include <asm/asm.h>
+#include <asm/regdef.h>
+#include <asm/mipsregs.h>
+#include <asm/stackframe.h>
+#include <asm/cacheops.h>
+#include <asm/sibyte/board.h>
+
+#define C0_ERRCTL     $26             /* CP0: Error info */
+#define C0_CERR_I     $27             /* CP0: Icache error */
+#define C0_CERR_D     $27,1           /* CP0: Dcache error */
+
+        /*
+         * Based on SiByte sample software cache-err/cerr.S
+         * CVS revision 1.8.  Only the 'unrecoverable' case
+         * is changed.
+         */
+
+        .set    mips64
+        .set    noreorder
+        .set    noat
+
+        /*
+         * sb1_cerr_vec: code to be copied to the Cache Error
+         * Exception vector.  The code must be pushed out to memory
+         * (either by copying to Kseg0 and Kseg1 both, or by flushing
+         * the L1 and L2) since it is fetched as 0xa0000100.
+         *
+         * NOTE: Be sure this handler is at most 28 instructions long
+         * since the final 16 bytes of the exception vector memory
+         * (0x170-0x17f) are used to preserve k0, k1, and ra.
+         */
+
+LEAF(except_vec2_sb1)
+        /*
+         * If this error is recoverable, we need to exit the handler
+         * without having dirtied any registers.  To do this,
+         * save/restore k0 and k1 from low memory (Useg is direct
+         * mapped while ERL=1). Note that we can't save to a
+         * CPU-specific location without ruining a register in the
+         * process.  This means we are vulnerable to data corruption
+         * whenever the handler is reentered by a second CPU.
+         */
+        sd      k0,0x170($0)
+        sd      k1,0x178($0)
+
+#ifdef CONFIG_SB1_CEX_ALWAYS_FATAL
+        j       handle_vec2_sb1
+         nop
+#else
+        /*
+         * M_ERRCTL_RECOVERABLE is bit 31, which makes it easy to tell
+         * if we can fast-path out of here for a h/w-recovered error.
+         */
+        mfc0    k1,C0_ERRCTL
+        bgtz    k1,attempt_recovery
+         sll    k0,k1,1
+
+recovered_dcache:
+        /*
+         * Unlock CacheErr-D (which in turn unlocks CacheErr-DPA).
+         * Ought to log the occurrence of this recovered dcache error.
+         */
+        b       recovered
+         mtc0   $0,C0_CERR_D
+
+attempt_recovery:
+        /*
+         * k0 has C0_ERRCTL << 1, which puts 'DC' at bit 31.  Any
+         * Dcache errors we can recover from will take more extensive
+         * processing.  For now, they are considered "unrecoverable".
+         * Note that 'DC' becoming set (outside of ERL mode) will
+         * cause 'IC' to clear; so if there's an Icache error, we'll
+         * only find out about it if we recover from this error and
+         * continue executing.
+         */
+        bltz    k0,unrecoverable
+         sll    k0,1
+
+        /*
+         * k0 has C0_ERRCTL << 2, which puts 'IC' at bit 31.  If an
+         * Icache error isn't indicated, I'm not sure why we got here.
+         * Consider that case "unrecoverable" for now.
+         */
+        bgez    k0,unrecoverable
+
+attempt_icache_recovery:
+        /*
+         * External icache errors are due to uncorrectable ECC errors
+         * in the L2 cache or Memory Controller and cannot be
+         * recovered here.
+         */
+         mfc0   k0,C0_CERR_I            /* delay slot */
+        li      k1,1 << 26              /* ICACHE_EXTERNAL */
+        and     k1,k0
+        bnez    k1,unrecoverable
+         andi   k0,0x1fe0
+
+        /*
+         * Since the error is internal, the 'IDX' field from
+         * CacheErr-I is valid and we can just invalidate all blocks
+         * in that set.
+         */
+        cache   Index_Invalidate_I,(0<<13)(k0)
+        cache   Index_Invalidate_I,(1<<13)(k0)
+        cache   Index_Invalidate_I,(2<<13)(k0)
+        cache   Index_Invalidate_I,(3<<13)(k0)
+
+        /* Ought to log this recovered icache error */
+
+recovered:
+        /* Restore the saved registers */
+        ld      k0,0x170($0)
+        ld      k1,0x178($0)
+        eret
+
+unrecoverable:
+        /* Unrecoverable Icache or Dcache error; log it and/or fail */
+        j       handle_vec2_sb1
+         nop
+#endif
+
+END(except_vec2_sb1)
+
+        LEAF(handle_vec2_sb1)
+        mfc0    k0,CP0_CONFIG
+        li      k1,~CONF_CM_CMASK
+        and     k0,k0,k1
+        ori     k0,k0,CONF_CM_UNCACHED
+        mtc0    k0,CP0_CONFIG
+
+        SSNOP
+        SSNOP
+        SSNOP
+        SSNOP
+        bnezl   $0, 1f
+1:
+        mfc0    k0, CP0_STATUS
+        sll     k0, k0, 3                       # check CU0 (kernel?)
+        bltz    k0, 2f
+         nop
+
+        /* Get a valid Kseg0 stack pointer.  Any task's stack pointer
+         * will do, although if we ever want to resume execution we
+         * better not have corrupted any state. */
+        get_saved_sp
+        move    sp, k1
+
+2:
+        j       sb1_cache_error
+         nop
+
+        END(handle_vec2_sb1)