[Blackfin] arch: Remove the circular buffering mechanism for exceptions

Remove the circular buffering mechanism for exceptions.  Instead, point RETX
at a safe location from which to fetch three NOPs.

This safe location is now in the fixed code area, and also used for certain
anomaly workarounds, to ensure that user space can find a valid ICPLB when
things are built with CONFIG_MPU.

Also, save I/DCPLB_FAULT_ADDRESS when lowering to level 5, since the hardware
reg is valid only at exception level.

Signed-off-by: Bernd Schmidt <bernds_cb1@t-online.de>
Signed-off-by: Bryan Wu <cooloney@kernel.org>

diff --git a/arch/blackfin/kernel/traps.c b/arch/blackfin/kernel/traps.c
index d0f6754220746c49a0f20c55876e1ed2237a850f..5b847070dae509f293827e327e32204d4be8e133 100644 (file)
--- a/arch/blackfin/kernel/traps.c
+++ b/arch/blackfin/kernel/traps.c
@@ -67,6 +67,8 @@ void __init trap_init(void)
        CSYNC();
 }
 
+void *saved_icplb_fault_addr, *saved_dcplb_fault_addr;
+
 int kstack_depth_to_print = 48;
 
 static void decode_address(char *buf, unsigned long address)
@@ -703,10 +705,7 @@ void dump_bfin_mem(struct pt_regs *fp)
        unsigned short *addr, *erraddr, val = 0, err = 0;
        char sti = 0, buf[6];
 
-       if (unlikely((fp->seqstat & SEQSTAT_EXCAUSE) == VEC_HWERR))
-               erraddr = (void *)fp->pc;
-       else
-               erraddr = (void *)fp->retx;
+       erraddr = (void *)fp->pc;
 
        printk(KERN_NOTICE "return address: [0x%p]; contents of:", erraddr);
 
@@ -830,9 +829,9 @@ unlock:
 
        if (((long)fp->seqstat &  SEQSTAT_EXCAUSE) &&
            (((long)fp->seqstat & SEQSTAT_EXCAUSE) != VEC_HWERR)) {
-               decode_address(buf, bfin_read_DCPLB_FAULT_ADDR());
+               decode_address(buf, saved_dcplb_fault_addr);
                printk(KERN_NOTICE "DCPLB_FAULT_ADDR: %s\n", buf);
-               decode_address(buf, bfin_read_ICPLB_FAULT_ADDR());
+               decode_address(buf, saved_icplb_fault_addr);
                printk(KERN_NOTICE "ICPLB_FAULT_ADDR: %s\n", buf);
        }
 
@@ -940,8 +939,8 @@ void panic_cplb_error(int cplb_panic, struct pt_regs *fp)
 
        oops_in_progress = 1;
 
-       printk(KERN_EMERG "DCPLB_FAULT_ADDR=%p\n", (void *)bfin_read_DCPLB_FAULT_ADDR());
-       printk(KERN_EMERG "ICPLB_FAULT_ADDR=%p\n", (void *)bfin_read_ICPLB_FAULT_ADDR());
+       printk(KERN_EMERG "DCPLB_FAULT_ADDR=%p\n", saved_dcplb_fault_addr);
+       printk(KERN_EMERG "ICPLB_FAULT_ADDR=%p\n", saved_icplb_fault_addr);
        dump_bfin_process(fp);
        dump_bfin_mem(fp);
        show_regs(fp);

diff --git a/arch/blackfin/mach-common/entry.S b/arch/blackfin/mach-common/entry.S
index a504c65d999022f9b39a79a12f7ccc61a82c6d17..f2fb87e9a46e29edfb5f04f2190ff337717e35da 100644 (file)
--- a/arch/blackfin/mach-common/entry.S
+++ b/arch/blackfin/mach-common/entry.S
@@ -38,6 +38,7 @@
 #include <linux/unistd.h>
 #include <asm/blackfin.h>
 #include <asm/errno.h>
+#include <asm/fixed_code.h>
 #include <asm/thread_info.h>  /* TIF_NEED_RESCHED */
 #include <asm/asm-offsets.h>
 #include <asm/trace.h>
@@ -52,15 +53,6 @@
 # define EX_SCRATCH_REG CYCLES
 #endif
 
-#if ANOMALY_05000281
-ENTRY(_safe_speculative_execution)
-       NOP;
-       NOP;
-       NOP;
-       jump _safe_speculative_execution;
-ENDPROC(_safe_speculative_execution)
-#endif
-
 #ifdef CONFIG_EXCPT_IRQ_SYSC_L1
 .section .l1.text
 #else
@@ -230,6 +222,26 @@ ENTRY(_ex_trap_c)
        [p4] = p5;
        csync;
 
+       p4.l = lo(DCPLB_FAULT_ADDR);
+       p4.h = hi(DCPLB_FAULT_ADDR);
+       r7 = [p4];
+       p5.h = _saved_dcplb_fault_addr;
+       p5.l = _saved_dcplb_fault_addr;
+       [p5] = r7;
+
+       r7 = [p4 + (ICPLB_FAULT_ADDR - DCPLB_FAULT_ADDR)];
+       p5.h = _saved_icplb_fault_addr;
+       p5.l = _saved_icplb_fault_addr;
+       [p5] = r7;
+
+       p4.l = __retx;
+       p4.h = __retx;
+       r6 = retx;
+       [p4] = r6;
+       p4.l = lo(SAFE_USER_INSTRUCTION);
+       p4.h = hi(SAFE_USER_INSTRUCTION);
+       retx = p4;
+
        /* Disable all interrupts, but make sure level 5 is enabled so
         * we can switch to that level.  Save the old mask.  */
        cli r6;
@@ -239,23 +251,6 @@ ENTRY(_ex_trap_c)
        r6 = 0x3f;
        sti r6;
 
-       /* Save the excause into a circular buffer, in case the instruction
-        * which caused this excecptions causes others.
-        */
-       P5.l = _in_ptr_excause;
-       P5.h = _in_ptr_excause;
-       R7 = [P5];
-       R7 += 4;
-       R6 = 0xF;
-       R7 = R7 & R6;
-       [P5] = R7;
-       R6.l = _excause_circ_buf;
-       R6.h = _excause_circ_buf;
-       R7 = R7 + R6;
-       p5 = R7;
-       R6 = SEQSTAT;
-       [P5] = R6;
-
        (R7:6,P5:4) = [sp++];
        ASTAT = [sp++];
        SP = EX_SCRATCH_REG;
@@ -312,6 +307,11 @@ ENDPROC(_double_fault)
 ENTRY(_exception_to_level5)
        SAVE_ALL_SYS
 
+       p4.l = __retx;
+       p4.h = __retx;
+       r6 = [p4];
+       [sp + PT_PC] = r6;
+
        /* Restore interrupt mask.  We haven't pushed RETI, so this
         * doesn't enable interrupts until we return from this handler.  */
        p4.l = _excpt_saved_imask;
@@ -333,42 +333,11 @@ ENTRY(_exception_to_level5)
        r0 = [p2];              /* Read current IPEND */
        [sp + PT_IPEND] = r0;   /* Store IPEND */
 
-       /* Pop the excause from the circular buffer and push it on the stack
-        * (in the right place - if you change the location of SEQSTAT, you
-        * must change this offset.
-        */
-.L_excep_to_5_again:
-       P5.l = _out_ptr_excause;
-       P5.h = _out_ptr_excause;
-       R7 = [P5];
-       R7 += 4;
-       R6 = 0xF;
-       R7 = R7 & R6;
-       [P5] = R7;
-       R6.l = _excause_circ_buf;
-       R6.h = _excause_circ_buf;
-       R7 = R7 + R6;
-       P5 = R7;
-       R1 = [P5];
-       [SP + PT_SEQSTAT] = r1;
-
        r0 = sp;        /* stack frame pt_regs pointer argument ==> r0 */
        SP += -12;
        call _trap_c;
        SP += 12;
 
-       /* See if anything else is in the exception buffer
-        * if there is, process it
-        */
-       P5.l = _out_ptr_excause;
-       P5.h = _out_ptr_excause;
-       P4.l = _in_ptr_excause;
-       P4.h = _in_ptr_excause;
-       R6 = [P5];
-       R7 = [P4];
-       CC = R6 == R7;
-       if ! CC JUMP .L_excep_to_5_again
-
        call _ret_from_exception;
        RESTORE_ALL_SYS
        rti;
@@ -732,8 +701,8 @@ ENTRY(_return_from_int)
        [p0] = p1;
        csync;
 #if ANOMALY_05000281
-       r0.l = _safe_speculative_execution;
-       r0.h = _safe_speculative_execution;
+       r0.l = lo(SAFE_USER_INSTRUCTION);
+       r0.h = hi(SAFE_USER_INSTRUCTION);
        reti = r0;
 #endif
        r0 = 0x801f (z);
@@ -746,8 +715,8 @@ ENDPROC(_return_from_int)
 
 ENTRY(_lower_to_irq14)
 #if ANOMALY_05000281
-       r0.l = _safe_speculative_execution;
-       r0.h = _safe_speculative_execution;
+       r0.l = lo(SAFE_USER_INSTRUCTION);
+       r0.h = hi(SAFE_USER_INSTRUCTION);
        reti = r0;
 #endif
        r0 = 0x401f;
@@ -814,20 +783,6 @@ _schedule_and_signal:
        rti;
 ENDPROC(_lower_to_irq14)
 
-/* Make sure when we start, that the circular buffer is initialized properly
- * R0 and P0 are call clobbered, so we can use them here.
- */
-ENTRY(_init_exception_buff)
-       r0 = 0;
-       p0.h = _in_ptr_excause;
-       p0.l = _in_ptr_excause;
-       [p0] = r0;
-       p0.h = _out_ptr_excause;
-       p0.l = _out_ptr_excause;
-       [p0] = r0;
-       rts;
-ENDPROC(_init_exception_buff)
-
 /* We handle this 100% in exception space - to reduce overhead
  * Only potiential problem is if the software buffer gets swapped out of the
  * CPLB table - then double fault. - so we don't let this happen in other places
@@ -1403,17 +1358,7 @@ _exception_stack_top:
 _last_cplb_fault_retx:
        .long 0;
 #endif
-/*
- * Single instructions can have multiple faults, which need to be
- * handled by traps.c, in irq5. We store the exception cause to ensure
- * we don't miss a double fault condition
- */
-ENTRY(_in_ptr_excause)
-       .long 0;
-ENTRY(_out_ptr_excause)
+       /* Used to save the real RETX when temporarily storing a safe
+        * return address.  */
+__retx:
        .long 0;
-ALIGN
-ENTRY(_excause_circ_buf)
-       .rept 4
-       .long 0
-       .endr

diff --git a/arch/blackfin/mach-common/ints-priority.c b/arch/blackfin/mach-common/ints-priority.c
index 5448230c0e9568007ecf20ed4bf024f0aa4834b8..f5fd768022eaeb13cab7d7be9dd24b8e86c6d5e7 100644 (file)
--- a/arch/blackfin/mach-common/ints-priority.c
+++ b/arch/blackfin/mach-common/ints-priority.c
@@ -939,8 +939,6 @@ int __init init_arch_irq(void)
 
        local_irq_disable();
 
-       init_exception_buff();
-
 #ifdef CONFIG_BF54x
 # ifdef CONFIG_PINTx_REASSIGN
        pint[0]->assign = CONFIG_PINT0_ASSIGN;