From d0f53c2f890deef5138ec3d873e15a8cfc3ff0c9 Mon Sep 17 00:00:00 2001 From: Atle Nissestad Date: Sun, 16 Dec 2007 16:11:21 +0100 Subject: [PATCH] nios2: Added breakpoint exception handler 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 --- 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 14f776a..e177492 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