s32i a0, a2, PT_DEPC # mark it as a regular exception
addx4 a0, a0, a3 # find entry in table
l32i a0, a0, EXC_TABLE_FAST_USER # load handler
+ xsr a3, excsave1 # restore a3 and dispatch table
jx a0
ENDPROC(_UserExceptionVector)
s32i a0, a2, PT_DEPC # mark it as a regular exception
addx4 a0, a0, a3 # find entry in table
l32i a0, a0, EXC_TABLE_FAST_KERNEL # load handler address
+ xsr a3, excsave1 # restore a3 and dispatch table
jx a0
ENDPROC(_KernelExceptionVector)
*
* a0: DEPC
* a1: a1
- * a2: trashed, original value in EXC_TABLE_DOUBLE_A2
+ * a2: trashed, original value in EXC_TABLE_DOUBLE_SAVE
* a3: exctable
* depc: a0
* excsave_1: a3
.section .DoubleExceptionVector.text, "ax"
.begin literal_prefix .DoubleExceptionVector
+ .globl _DoubleExceptionVector_WindowUnderflow
+ .globl _DoubleExceptionVector_WindowOverflow
ENTRY(_DoubleExceptionVector)
- /* Deliberately destroy excsave (don't assume it's value was valid). */
-
- wsr a3, excsave1 # save a3
+ xsr a3, excsave1
+ s32i a2, a3, EXC_TABLE_DOUBLE_SAVE
/* Check for kernel double exception (usually fatal). */
- rsr a3, ps
- _bbci.l a3, PS_UM_BIT, .Lksp
+ rsr a2, ps
+ _bbci.l a2, PS_UM_BIT, .Lksp
/* Check if we are currently handling a window exception. */
/* Note: We don't need to indicate that we enter a critical section. */
xsr a0, depc # get DEPC, save a0
- movi a3, WINDOW_VECTORS_VADDR
- _bltu a0, a3, .Lfixup
- addi a3, a3, WINDOW_VECTORS_SIZE
- _bgeu a0, a3, .Lfixup
+ movi a2, WINDOW_VECTORS_VADDR
+ _bltu a0, a2, .Lfixup
+ addi a2, a2, WINDOW_VECTORS_SIZE
+ _bgeu a0, a2, .Lfixup
/* Window overflow/underflow exception. Get stack pointer. */
- mov a3, a2
- /* This explicit literal and the following references to it are made
- * in order to fit DoubleExceptionVector.literals into the available
- * 16-byte gap before DoubleExceptionVector.text in the absence of
- * link time relaxation. See kernel/vmlinux.lds.S
- */
- .literal .Lexc_table, exc_table
- l32r a2, .Lexc_table
- l32i a2, a2, EXC_TABLE_KSTK
+ l32i a2, a3, EXC_TABLE_KSTK
/* Check for overflow/underflow exception, jump if overflow. */
- _bbci.l a0, 6, .Lovfl
-
- /* a0: depc, a1: a1, a2: kstk, a3: a2, depc: a0, excsave: a3 */
+ _bbci.l a0, 6, _DoubleExceptionVector_WindowOverflow
- /* Restart window underflow exception.
+ /*
+ * Restart window underflow exception.
+ * Currently:
+ * depc = orig a0,
+ * a0 = orig DEPC,
+ * a2 = new sp based on KSTK from exc_table
+ * a3 = excsave_1
+ * excsave_1 = orig a3
+ *
* We return to the instruction in user space that caused the window
* underflow exception. Therefore, we change window base to the value
* before we entered the window underflow exception and prepare the
* by changing depc (in a0).
* Note: We can trash the current window frame (a0...a3) and depc!
*/
-
+_DoubleExceptionVector_WindowUnderflow:
+ xsr a3, excsave1
wsr a2, depc # save stack pointer temporarily
rsr a0, ps
- extui a0, a0, PS_OWB_SHIFT, 4
+ extui a0, a0, PS_OWB_SHIFT, PS_OWB_WIDTH
wsr a0, windowbase
rsync
xsr a2, depc # save a2 and get stack pointer
s32i a0, a2, PT_AREG0
-
- wsr a3, excsave1 # save a3
- l32r a3, .Lexc_table
-
+ xsr a3, excsave1
rsr a0, exccause
s32i a0, a2, PT_DEPC # mark it as a regular exception
addx4 a0, a0, a3
+ xsr a3, excsave1
l32i a0, a0, EXC_TABLE_FAST_USER
jx a0
-.Lfixup:/* Check for a fixup handler or if we were in a critical section. */
+ /*
+ * We only allow the ITLB miss exception if we are in kernel space.
+ * All other exceptions are unexpected and thus unrecoverable!
+ */
+
+#ifdef CONFIG_MMU
+ .extern fast_second_level_miss_double_kernel
+
+.Lksp: /* a0: a0, a1: a1, a2: a2, a3: trashed, depc: depc, excsave: a3 */
+
+ rsr a3, exccause
+ beqi a3, EXCCAUSE_ITLB_MISS, 1f
+ addi a3, a3, -EXCCAUSE_DTLB_MISS
+ bnez a3, .Lunrecoverable
+1: movi a3, fast_second_level_miss_double_kernel
+ jx a3
+#else
+.equ .Lksp, .Lunrecoverable
+#endif
+
+ /* Critical! We can't handle this situation. PANIC! */
- /* a0: depc, a1: a1, a2: a2, a3: trashed, depc: a0, excsave1: a3 */
+ .extern unrecoverable_exception
- l32r a3, .Lexc_table
- s32i a2, a3, EXC_TABLE_DOUBLE_SAVE # temporary variable
+.Lunrecoverable_fixup:
+ l32i a2, a3, EXC_TABLE_DOUBLE_SAVE
+ xsr a0, depc
+
+.Lunrecoverable:
+ rsr a3, excsave1
+ wsr a0, excsave1
+ movi a0, unrecoverable_exception
+ callx0 a0
+
+.Lfixup:/* Check for a fixup handler or if we were in a critical section. */
+
+ /* a0: depc, a1: a1, a2: trash, a3: exctable, depc: a0, excsave1: a3 */
/* Enter critical section. */
l32i a2, a3, EXC_TABLE_FIXUP
s32i a3, a3, EXC_TABLE_FIXUP
- beq a2, a3, .Lunrecoverable_fixup # critical!
+ beq a2, a3, .Lunrecoverable_fixup # critical section
beqz a2, .Ldflt # no handler was registered
/* a0: depc, a1: a1, a2: trash, a3: exctable, depc: a0, excsave: a3 */
.Ldflt: /* Get stack pointer. */
- l32i a3, a3, EXC_TABLE_DOUBLE_SAVE
- addi a2, a3, -PT_USER_SIZE
-
-.Lovfl: /* Jump to default handlers. */
+ l32i a2, a3, EXC_TABLE_DOUBLE_SAVE
+ addi a2, a2, -PT_USER_SIZE
- /* a0: depc, a1: a1, a2: kstk, a3: a2, depc: a0, excsave: a3 */
+ /* a0: depc, a1: a1, a2: kstk, a3: exctable, depc: a0, excsave: a3 */
- xsr a3, depc
s32i a0, a2, PT_DEPC
- s32i a3, a2, PT_AREG0
+ l32i a0, a3, EXC_TABLE_DOUBLE_SAVE
+ xsr a0, depc
+ s32i a0, a2, PT_AREG0
- /* a0: avail, a1: a1, a2: kstk, a3: avail, depc: a2, excsave: a3 */
+ /* a0: avail, a1: a1, a2: kstk, a3: exctable, depc: a2, excsave: a3 */
- l32r a3, .Lexc_table
rsr a0, exccause
addx4 a0, a0, a3
+ xsr a3, excsave1
l32i a0, a0, EXC_TABLE_FAST_USER
jx a0
/*
- * We only allow the ITLB miss exception if we are in kernel space.
- * All other exceptions are unexpected and thus unrecoverable!
+ * Restart window OVERFLOW exception.
+ * Currently:
+ * depc = orig a0,
+ * a0 = orig DEPC,
+ * a2 = new sp based on KSTK from exc_table
+ * a3 = EXCSAVE_1
+ * excsave_1 = orig a3
+ *
+ * We return to the instruction in user space that caused the window
+ * overflow exception. Therefore, we change window base to the value
+ * before we entered the window overflow exception and prepare the
+ * registers to return as if we were coming from a regular exception
+ * by changing DEPC (in a0).
+ *
+ * NOTE: We CANNOT trash the current window frame (a0...a3), but we
+ * can clobber depc.
+ *
+ * The tricky part here is that overflow8 and overflow12 handlers
+ * save a0, then clobber a0. To restart the handler, we have to restore
+ * a0 if the double exception was past the point where a0 was clobbered.
+ *
+ * To keep things simple, we take advantage of the fact all overflow
+ * handlers save a0 in their very first instruction. If DEPC was past
+ * that instruction, we can safely restore a0 from where it was saved
+ * on the stack.
+ *
+ * a0: depc, a1: a1, a2: kstk, a3: exc_table, depc: a0, excsave1: a3
*/
+_DoubleExceptionVector_WindowOverflow:
+ extui a2, a0, 0, 6 # get offset into 64-byte vector handler
+ beqz a2, 1f # if at start of vector, don't restore
-#ifdef CONFIG_MMU
- .extern fast_second_level_miss_double_kernel
+ addi a0, a0, -128
+ bbsi a0, 8, 1f # don't restore except for overflow 8 and 12
+ bbsi a0, 7, 2f
-.Lksp: /* a0: a0, a1: a1, a2: a2, a3: trashed, depc: depc, excsave: a3 */
+ /*
+ * Restore a0 as saved by _WindowOverflow8().
+ *
+ * FIXME: we really need a fixup handler for this L32E,
+ * for the extremely unlikely case where the overflow handler's
+ * reference thru a0 gets a hardware TLB refill that bumps out
+ * the (distinct, aliasing) TLB entry that mapped its prior
+ * references thru a9, and where our reference now thru a9
+ * gets a 2nd-level miss exception (not hardware TLB refill).
+ */
- rsr a3, exccause
- beqi a3, EXCCAUSE_ITLB_MISS, 1f
- addi a3, a3, -EXCCAUSE_DTLB_MISS
- bnez a3, .Lunrecoverable
-1: movi a3, fast_second_level_miss_double_kernel
- jx a3
-#else
-.equ .Lksp, .Lunrecoverable
-#endif
+ l32e a2, a9, -16
+ wsr a2, depc # replace the saved a0
+ j 1f
- /* Critical! We can't handle this situation. PANIC! */
+2:
+ /*
+ * Restore a0 as saved by _WindowOverflow12().
+ *
+ * FIXME: we really need a fixup handler for this L32E,
+ * for the extremely unlikely case where the overflow handler's
+ * reference thru a0 gets a hardware TLB refill that bumps out
+ * the (distinct, aliasing) TLB entry that mapped its prior
+ * references thru a13, and where our reference now thru a13
+ * gets a 2nd-level miss exception (not hardware TLB refill).
+ */
- .extern unrecoverable_exception
+ l32e a2, a13, -16
+ wsr a2, depc # replace the saved a0
+1:
+ /*
+ * Restore WindowBase while leaving all address registers restored.
+ * We have to use ROTW for this, because WSR.WINDOWBASE requires
+ * an address register (which would prevent restore).
+ *
+ * Window Base goes from 0 ... 7 (Module 8)
+ * Window Start is 8 bits; Ex: (0b1010 1010):0x55 from series of call4s
+ */
+
+ rsr a0, ps
+ extui a0, a0, PS_OWB_SHIFT, PS_OWB_WIDTH
+ rsr a2, windowbase
+ sub a0, a2, a0
+ extui a0, a0, 0, 3
-.Lunrecoverable_fixup:
l32i a2, a3, EXC_TABLE_DOUBLE_SAVE
- xsr a0, depc
+ xsr a3, excsave1
+ beqi a0, 1, .L1pane
+ beqi a0, 3, .L3pane
-.Lunrecoverable:
- rsr a3, excsave1
- wsr a0, excsave1
- movi a0, unrecoverable_exception
- callx0 a0
+ rsr a0, depc
+ rotw -2
+
+ /*
+ * We are now in the user code's original window frame.
+ * Process the exception as a user exception as if it was
+ * taken by the user code.
+ *
+ * This is similar to the user exception vector,
+ * except that PT_DEPC isn't set to EXCCAUSE.
+ */
+1:
+ xsr a3, excsave1
+ wsr a2, depc
+ l32i a2, a3, EXC_TABLE_KSTK
+ s32i a0, a2, PT_AREG0
+ rsr a0, exccause
+
+ s32i a0, a2, PT_DEPC
+
+ addx4 a0, a0, a3
+ l32i a0, a0, EXC_TABLE_FAST_USER
+ xsr a3, excsave1
+ jx a0
+
+.L1pane:
+ rsr a0, depc
+ rotw -1
+ j 1b
+
+.L3pane:
+ rsr a0, depc
+ rotw -3
+ j 1b
.end literal_prefix
projects / karo-tx-linux.git / blobdiff