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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH ARM v4 08/12] mini-os: arm: show registers, stack and exception vector on fault
Signed-off-by: Thomas Leonard <talex5@xxxxxxxxx>
---
extras/mini-os/ARM-TODO.txt | 1 -
extras/mini-os/arch/arm/arm32.S | 81 ++++++++++++++++++++++++++---
extras/mini-os/arch/arm/panic.c | 99 ++++++++++++++++++++++++++++++++++++
extras/mini-os/include/arm/arch_mm.h | 2 +-
extras/mini-os/include/arm/os.h | 2 +-
5 files changed, 175 insertions(+), 10 deletions(-)
create mode 100644 extras/mini-os/arch/arm/panic.c
diff --git a/extras/mini-os/ARM-TODO.txt b/extras/mini-os/ARM-TODO.txt
index 3d9be10..8f4f1da 100644
--- a/extras/mini-os/ARM-TODO.txt
+++ b/extras/mini-os/ARM-TODO.txt
@@ -1,4 +1,3 @@
-* support abort exception handling ( and others )
* scheduling!
* gic request_irq implementation, currently all IRQs all hardcoded in gic irq
handler.
* use device tree instead of the currently hardcoded values
diff --git a/extras/mini-os/arch/arm/arm32.S b/extras/mini-os/arch/arm/arm32.S
index 4f953ec..29fba72 100644
--- a/extras/mini-os/arch/arm/arm32.S
+++ b/extras/mini-os/arch/arm/arm32.S
@@ -80,16 +80,83 @@ shared_info_page:
.align 3
.globl stack
+.globl stack_end
stack:
.fill (4*1024), 4, 0x0
stack_end:
.align 3
+.globl irqstack
+.globl irqstack_end
irqstack:
.fill (1024), 4, 0x0
irqstack_end:
+
+fault_dump:
+ .fill 18, 4, 0x0 @ On fault, we save the registers +
CPSR + handler address
+
.popsection
+fault:
+ cpsid aif @ Disable interrupts
+
+ ldr r13, =fault_dump
+ stmia r13, {r0-r12} @ Dump the non-banked registers
directly (well, unless from FIQ mode)
+ str r14, [r13, #15 << 2] @ Our r14 is the faulting r15
+ mov r0, r13
+
+ @ Save the caller's CPSR (our SPSR) too.
+ mrs r1, SPSR
+ str r1, [r13, #16 << 2]
+
+ @ Switch to the mode we came from to get r13 and r14.
+ @ If coming from user mode, use System mode instead so we're still
+ @ privileged.
+ and r1, r1, #0x1f @ r1 = SPSR mode
+ cmp r1, #0x10 @ If from User mode
+ moveq r1, #0x1f @ Then use System mode instead
+
+ mrs r3, CPSR @ r3 = our CPSR
+ bic r2, r3, #0x1f
+ orr r2, r2, r1
+ msr CPSR, r2 @ Change to mode r1
+
+ @ Save old mode's r13, r14
+ str r13, [r0, #13 << 2]
+ str r14, [r0, #14 << 2]
+
+ msr CPSR, r3 @ Back to fault mode
+
+ ldr r1, [r0, #17 << 2]
+ sub r1, r1, #12 @ Fix to point at start of handler
+ str r1, [r0, #17 << 2]
+
+ @ Call C code to format the register dump.
+ @ Clobbers the stack, but we're not going to return anyway.
+ ldr r13, =stack_end
+ bl dump_registers
+1:
+ wfi
+ b 1b
+
+@ We want to store a unique value to identify this handler, without corrupting
+@ any of the registers. So, we store r15 (which will point just after the
branch).
+@ Later, we subtract 12 so the user gets pointed at the start of the exception
+@ handler.
+#define FAULT(name) \
+.globl fault_##name; \
+fault_##name: \
+ ldr r13, =fault_dump; \
+ str r15, [r13, #17 << 2]; \
+ b fault
+
+FAULT(reset)
+FAULT(undefined_instruction)
+FAULT(svc)
+FAULT(prefetch_call)
+FAULT(prefetch_abort)
+FAULT(data_abort)
+
@ exception base address
.align 5
.globl exception_vector_table
@@ -99,13 +166,13 @@ irqstack_end:
@ instruction to clear an existing tag is required on context switches."
@ -- ARM Cortex-A Series Programmerâs Guide (Version: 4.0)
exception_vector_table:
- b . @ reset
- b . @ undefined instruction
- b . @ supervisor call
- b . @ prefetch call
- b . @ prefetch abort
- b . @ data abort
- b irq_handler @ irq
+ b fault_reset
+ b fault_undefined_instruction
+ b fault_svc
+ b fault_prefetch_call
+ b fault_prefetch_abort
+ b fault_data_abort
+ b irq_handler @ IRQ
.word 0xe7f000f0 @ abort on FIQ
irq_handler:
diff --git a/extras/mini-os/arch/arm/panic.c b/extras/mini-os/arch/arm/panic.c
new file mode 100644
index 0000000..12735d6
--- /dev/null
+++ b/extras/mini-os/arch/arm/panic.c
@@ -0,0 +1,99 @@
+/******************************************************************************
+ * panic.c
+ *
+ * Displays a register dump and stack trace for debugging.
+ *
+ * Copyright (c) 2014, Thomas Leonard
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+#include <mini-os/os.h>
+#include <arch_mm.h>
+
+extern int stack[];
+extern int stack_end[];
+extern int irqstack[];
+extern int irqstack_end[];
+
+typedef void handler(void);
+
+extern handler fault_reset;
+extern handler fault_undefined_instruction;
+extern handler fault_svc;
+extern handler fault_prefetch_call;
+extern handler fault_prefetch_abort;
+extern handler fault_data_abort;
+
+void dump_registers(int *saved_registers) {
+ static int in_dump = 0;
+ int *sp, *stack_top, *x;
+ char *fault_name;
+ void *fault_handler;
+ int i;
+
+ if (in_dump)
+ {
+ printk("Crash while in dump_registers! Not generating a second
report.\n");
+ return;
+ }
+
+ in_dump = 1;
+
+ fault_handler = (handler *) saved_registers[17];
+ if (fault_handler == fault_reset)
+ fault_name = "reset";
+ else if (fault_handler == fault_undefined_instruction)
+ fault_name = "undefined_instruction";
+ else if (fault_handler == fault_svc)
+ fault_name = "svc";
+ else if (fault_handler == fault_prefetch_call)
+ fault_name = "prefetch_call";
+ else if (fault_handler == fault_prefetch_abort)
+ fault_name = "prefetch_abort";
+ else if (fault_handler == fault_data_abort)
+ fault_name = "data_abort";
+ else
+ fault_name = "unknown fault type!";
+
+ printk("Fault handler at %x called (%s)\n", fault_handler, fault_name);
+
+ for (i = 0; i < 16; i++) {
+ printk("r%d = %x\n", i, saved_registers[i]);
+ }
+ printk("CPSR = %x\n", saved_registers[16]);
+
+ printk("Stack dump (innermost last)\n");
+ sp = (int *) saved_registers[13];
+
+ if (sp >= stack && sp <= stack_end)
+ stack_top = stack_end; /* The small boot
stack */
+ else if (sp >= irqstack && sp <= irqstack_end)
+ stack_top = irqstack_end; /* The small IRQ stack
*/
+ else
+ stack_top = (int *) ((((unsigned long) sp) | (__STACK_SIZE-1)) + 1);
/* A normal thread stack */
+
+ for (x = stack_top - 1; x >= sp; x--)
+ {
+ printk(" [%8p] %8x\n", x, *x);
+ }
+ printk("End of stack\n");
+
+ in_dump = 0;
+}
diff --git a/extras/mini-os/include/arm/arch_mm.h
b/extras/mini-os/include/arm/arch_mm.h
index be14ada..e943a9b 100644
--- a/extras/mini-os/include/arm/arch_mm.h
+++ b/extras/mini-os/include/arm/arch_mm.h
@@ -2,7 +2,7 @@
#define _ARCH_MM_H_
extern char _text, _etext, _erodata, _edata, _end, __bss_start;
-extern char stack[];
+extern int stack[];
#define PAGE_SHIFT 12
#define PAGE_SIZE (1 << PAGE_SHIFT)
diff --git a/extras/mini-os/include/arm/os.h b/extras/mini-os/include/arm/os.h
index 21e9276..8d76089 100644
--- a/extras/mini-os/include/arm/os.h
+++ b/extras/mini-os/include/arm/os.h
@@ -10,7 +10,7 @@
void arch_fini(void);
void timer_handler(evtchn_port_t port, struct pt_regs *regs, void *ign);
-#define BUG() while(1){}
+#define BUG() while(1){asm volatile (".word 0xe7f000f0\n");} /* Undefined
instruction; will call our fault handler. */
#define smp_processor_id() 0
--
2.0.0
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