patch-2.4.25 linux-2.4.25/arch/mips64/mm/cex-sb1.S

• Lines: 169
• Date: 2004-02-18 05:36:30.000000000 -0800
• Orig file: linux-2.4.24/arch/mips64/mm/cex-sb1.S
• Orig date: 2003-08-25 04:44:40.000000000 -0700

diff -urN linux-2.4.24/arch/mips64/mm/cex-sb1.S linux-2.4.25/arch/mips64/mm/cex-sb1.S
@@ -22,40 +22,122 @@
 #include <asm/regdef.h>
 #include <asm/mipsregs.h>
 #include <asm/stackframe.h>
+#include <asm/cacheops.h>
+#include <asm/processor.h>
 #include <asm/sibyte/board.h>
 
-	.text
-	.set	noat
-	.set	mips4
+#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.
+	 */
 
         __INIT
-        
-	/* Cache Error handler for SB1 */
-	LEAF(except_vec2_sb1)
-	mfc0	k1, $26
-	# check if error was recoverable
-	bltz	k1, leave_cerr
-#ifdef CONFIG_SB1_PASS_1_WORKAROUNDS
-	# look for signature of spurious CErr
-	lui	k0, 0x4000
-	bne	k0, k1, 1f
-	.word	0x401Bd801			# mfc0	k1, $27, 1
-	lui	k0, 0xffe0
-	and	k1, k0, k1
-	lui	k0, 0x0200
-	beq	k0, k1, leave_cerr
-1:
-#endif
-	j	handle_vec2_sb1
 
-leave_cerr:
-	# clear/unlock the registers
-	mtc0	zero, $26
-	mtc0	zero, $27
-	.word	0x4080d801			# mtc0	zero, $27, 1
-	.word	0x4080d803			# mtc0	zero, $27, 3
+	.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)
+
+	/*
+	 * 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 occurence of this recovered dcache error.
+	 */
+	b	recovered
+	 .word   0x4080d801		# mtc0  zero, $27, 1
+
+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
-	END(except_vec2_sb1)
+
+unrecoverable:
+	/* Unrecoverable Icache or Dcache error; log it and/or fail */
+	j	handle_vec2_sb1
+	 nop
+
+END(except_vec2_sb1)
 
 	__FINIT
 
@@ -75,9 +157,16 @@
 	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				# want Kseg SP (so uncached)
+	move	sp, k1
+
 2:
 	j	sb1_cache_error
+	 nop
 
 	END(handle_vec2_sb1)