From: Atle Nissestad <[EMAIL PROTECTED]>
This is an initial attempt of enabling gdb/gdbserver application debug support
on the nios2 platform. To distinguish a gdb breakpoint from a system call, we
put
an immediate value of 1 into the trap instruction. In the instruction set the
immediate
value is undefined for trap, but apparently the instruction decoder recognizes
the
instruction anyway. Thus we in the kernel exception handler can do an
additional check
for imme=1 if a trap instruction is detected, and then run an appropriate
handler.
Signed-off-by: Atle Nissestad <[EMAIL PROTECTED]>
---
linux-2.6.x/arch/nios2nommu/kernel/entry.S | 7 +++++++
linux-2.6.x/arch/nios2nommu/kernel/traps.c | 16 ++++++++++++++++
2 files changed, 23 insertions(+), 0 deletions(-)
diff --git a/linux-2.6.x/arch/nios2nommu/kernel/entry.S
b/linux-2.6.x/arch/nios2nommu/kernel/entry.S
index 7f71a01..93fbc74 100644
--- a/linux-2.6.x/arch/nios2nommu/kernel/entry.S
+++ b/linux-2.6.x/arch/nios2nommu/kernel/entry.S
@@ -125,6 +125,8 @@ software_exception:
ldw r24,-4(ea) // instruction that caused the exception
xorhi r24,r24,0x003b // upper half of trap opcode
xori r24,r24,0x683a // lower half of trap opcode
+ cmpeqi r11,r24,0x40 /* Check for imm=0x01 => breakpoint */
+ bne r11,r0,breakpoint
bne r24,r0,instruction_trap /* N - check for instruction trap */
cmpeqi r11,r2,TRAP_ID_SYSCALL /* ? Is this a syscall */
bne r11,r0,system_call /* Y - handle syscall */
@@ -142,6 +144,11 @@ app_debug:
stw r24,(TASK_THREAD + THREAD_FLAGS)(r1) /* save
thread_info->task->thread.flags */
br restore_all
+breakpoint:
+ mov r4,sp
+ call breakpoint_c
+ br restore_all
+
/*
* This is the generic interrupt handler (for all hardware interrupt
* sources). It figures out the vector number and calls the appropriate
diff --git a/linux-2.6.x/arch/nios2nommu/kernel/traps.c
b/linux-2.6.x/arch/nios2nommu/kernel/traps.c
index 14b7e4c..6c55c04 100644
--- a/linux-2.6.x/arch/nios2nommu/kernel/traps.c
+++ b/linux-2.6.x/arch/nios2nommu/kernel/traps.c
@@ -176,3 +176,19 @@ void trap_init(void)
printk("trap_init reached\n");
#endif
}
+
+/* Breakpoint handler */
+asmlinkage void breakpoint_c(struct pt_regs *fp)
+{
+ siginfo_t info;
+
+/*
+ printk(KERN_DEBUG "Breakpoint detected, instr=0x%08x ea=0x%08x
ra=0x%08x sp=0x%08x\n", *(u32*)((fp->ea)-4), *(u32*)(fp->ea), *(u32*)(fp->ra),
*(u32*)(fp->sp));
+*/
+
+ info.si_code = TRAP_BRKPT;
+ info.si_signo = SIGTRAP;
+ info.si_errno = 0;
+
+ force_sig_info(info.si_signo, &info, current);
+}
--
1.5.3.3
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