From: Jason Wessel CC: ralf@linux-mips.org Subject: [PATCH] kgdb, mips: add arch support for the kernel's kgdb core The new kgdb architecture specific handler registers and unregisters dynamically for exceptions depending on when you configure a kgdb I/O driver. Aside from initializing the exceptions earlier in the boot process, kgdb should have no impact on a device when it is compiled in so long as an I/O module is not configured for use. There have been quite a number of contributors during the existence of this patch (see arch/mips/kernel/kgdb.c). Most recently Jason re-wrote the mips kgdb logic to use the die notification handlers. Signed-off-by: Jason Wessel --- arch/mips/Kconfig | 1 arch/mips/kernel/Makefile | 1 arch/mips/kernel/irq.c | 15 ++ arch/mips/kernel/kgdb.c | 285 ++++++++++++++++++++++++++++++++++++++++++++++ arch/mips/kernel/traps.c | 21 +++ include/asm-mips/kdebug.h | 14 ++ include/asm-mips/kgdb.h | 44 +++++++ 7 files changed, 380 insertions(+), 1 deletion(-) --- a/arch/mips/kernel/Makefile +++ b/arch/mips/kernel/Makefile @@ -71,6 +71,7 @@ obj-$(CONFIG_MIPS32_COMPAT) += linux32.o obj-$(CONFIG_MIPS32_N32) += binfmt_elfn32.o scall64-n32.o signal_n32.o obj-$(CONFIG_MIPS32_O32) += binfmt_elfo32.o scall64-o32.o +obj-$(CONFIG_KGDB) += kgdb.o obj-$(CONFIG_PROC_FS) += proc.o obj-$(CONFIG_64BIT) += cpu-bugs64.o --- a/arch/mips/kernel/irq.c +++ b/arch/mips/kernel/irq.c @@ -21,11 +21,16 @@ #include #include #include +#include #include #include #include +#ifdef CONFIG_KGDB +int kgdb_early_setup; +#endif + static unsigned long irq_map[NR_IRQS / BITS_PER_LONG]; int allocate_irqno(void) @@ -130,8 +135,18 @@ void __init init_IRQ(void) { int i; +#ifdef CONFIG_KGDB + if (kgdb_early_setup) + return; +#endif + for (i = 0; i < NR_IRQS; i++) set_irq_noprobe(i); arch_init_irq(); + +#ifdef CONFIG_KGDB + if (!kgdb_early_setup) + kgdb_early_setup = 1; +#endif } --- /dev/null +++ b/arch/mips/kernel/kgdb.c @@ -0,0 +1,285 @@ +/* + * arch/mips/kernel/kgdb.c + * + * Originally written by Glenn Engel, Lake Stevens Instrument Division + * + * Contributed by HP Systems + * + * Modified for Linux/MIPS (and MIPS in general) by Andreas Busse + * Send complaints, suggestions etc. to + * + * Copyright (C) 1995 Andreas Busse + * + * Copyright (C) 2003 MontaVista Software Inc. + * Author: Jun Sun, jsun@mvista.com or jsun@junsun.net + * + * Copyright (C) 2004-2005 MontaVista Software Inc. + * Author: Manish Lachwani, mlachwani@mvista.com or manish@koffee-break.com + * + * Copyright (C) 2007-2008 Wind River Systems, Inc. + * Author/Maintainer: Jason Wessel, jason.wessel@windriver.com + * + * This file is licensed under the terms of the GNU General Public License + * version 2. This program is licensed "as is" without any warranty of any + * kind, whether express or implied. + */ + +#include /* for linux pt_regs struct */ +#include +#include +#include +#include +#include +#include +#include + +static struct hard_trap_info { + unsigned char tt; /* Trap type code for MIPS R3xxx and R4xxx */ + unsigned char signo; /* Signal that we map this trap into */ +} hard_trap_info[] = { + { 6, SIGBUS }, /* instruction bus error */ + { 7, SIGBUS }, /* data bus error */ + { 9, SIGTRAP }, /* break */ +/* { 11, SIGILL }, */ /* CPU unusable */ + { 12, SIGFPE }, /* overflow */ + { 13, SIGTRAP }, /* trap */ + { 14, SIGSEGV }, /* virtual instruction cache coherency */ + { 15, SIGFPE }, /* floating point exception */ + { 23, SIGSEGV }, /* watch */ + { 31, SIGSEGV }, /* virtual data cache coherency */ + { 0, 0} /* Must be last */ +}; + +void arch_kgdb_breakpoint(void) +{ + __asm__ __volatile__( + ".globl breakinst\n\t" + ".set\tnoreorder\n\t" + "nop\n" + "breakinst:\tbreak\n\t" + "nop\n\t" + ".set\treorder"); +} + +static void kgdb_call_nmi_hook(void *ignored) +{ + kgdb_nmicallback(raw_smp_processor_id(), (void *)0); +} + +void kgdb_roundup_cpus(unsigned long flags) +{ + local_irq_enable(); + smp_call_function(kgdb_call_nmi_hook, NULL, NULL); + local_irq_disable(); +} + +static int compute_signal(int tt) +{ + struct hard_trap_info *ht; + + for (ht = hard_trap_info; ht->tt && ht->signo; ht++) + if (ht->tt == tt) + return ht->signo; + + return SIGHUP; /* default for things we don't know about */ +} + +void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs) +{ + int reg; + +#if (KGDB_GDB_REG_SIZE == 32) + u32 *ptr = (u32 *)gdb_regs; +#else + u64 *ptr = (u64 *)gdb_regs; +#endif + + for (reg = 0; reg < 32; reg++) + *(ptr++) = regs->regs[reg]; + + *(ptr++) = regs->cp0_status; + *(ptr++) = regs->lo; + *(ptr++) = regs->hi; + *(ptr++) = regs->cp0_badvaddr; + *(ptr++) = regs->cp0_cause; + *(ptr++) = regs->cp0_epc; + + /* FP REGS */ + if (!(current && (regs->cp0_status & ST0_CU1))) + return; + + save_fp(current); + for (reg = 0; reg < 32; reg++) + *(ptr++) = current->thread.fpu.fpr[reg]; + + return; +} + +void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *regs) +{ + int reg; + +#if (KGDB_GDB_REG_SIZE == 32) + const u32 *ptr = (u32 *)gdb_regs; +#else + const u64 *ptr = (u64 *)gdb_regs; +#endif + + for (reg = 0; reg < 32; reg++) + regs->regs[reg] = *(ptr++); + + regs->cp0_status = *(ptr++); + regs->lo = *(ptr++); + regs->hi = *(ptr++); + regs->cp0_badvaddr = *(ptr++); + regs->cp0_cause = *(ptr++); + regs->cp0_epc = *(ptr++); + + /* FP REGS from current */ + if (!(current && (regs->cp0_status & ST0_CU1))) + return; + + for (reg = 0; reg < 32; reg++) + current->thread.fpu.fpr[reg] = *(ptr++); + restore_fp(current); + + return; +} + +/* + * Similar to regs_to_gdb_regs() except that process is sleeping and so + * we may not be able to get all the info. + */ +void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p) +{ + int reg; + struct thread_info *ti = task_thread_info(p); + unsigned long ksp = (unsigned long)ti + THREAD_SIZE - 32; + struct pt_regs *regs = (struct pt_regs *)ksp - 1; +#if (KGDB_GDB_REG_SIZE == 32) + u32 *ptr = (u32 *)gdb_regs; +#else + u64 *ptr = (u64 *)gdb_regs; +#endif + + for (reg = 0; reg < 16; reg++) + *(ptr++) = regs->regs[reg]; + + /* S0 - S7 */ + for (reg = 16; reg < 24; reg++) + *(ptr++) = regs->regs[reg]; + + for (reg = 24; reg < 28; reg++) + *(ptr++) = 0; + + /* GP, SP, FP, RA */ + for (reg = 28; reg < 32; reg++) + *(ptr++) = regs->regs[reg]; + + *(ptr++) = regs->cp0_status; + *(ptr++) = regs->lo; + *(ptr++) = regs->hi; + *(ptr++) = regs->cp0_badvaddr; + *(ptr++) = regs->cp0_cause; + *(ptr++) = regs->cp0_epc; + + return; +} + +/* + * Calls linux_debug_hook before the kernel dies. If KGDB is enabled, + * then try to fall into the debugger + */ +static int kgdb_mips_notify(struct notifier_block *self, unsigned long cmd, + void *ptr) +{ + struct die_args *args = (struct die_args *)ptr; + struct pt_regs *regs = args->regs; + int trap = (regs->cp0_cause & 0x7c) >> 2; + + if (fixup_exception(regs)) + return NOTIFY_DONE; + + /* Userpace events, ignore. */ + if (user_mode(regs)) + return NOTIFY_DONE; + + if (atomic_read(&kgdb_active) != -1) + kgdb_nmicallback(smp_processor_id(), regs); + + if (kgdb_handle_exception(trap, compute_signal(trap), 0, regs)) + return NOTIFY_DONE; + + if (atomic_read(&kgdb_setting_breakpoint)) + if ((trap == 9) && (regs->cp0_epc == (unsigned long)breakinst)) + regs->cp0_epc += 4; + + /* In SMP mode, __flush_cache_all does IPI */ + local_irq_enable(); + __flush_cache_all(); + + return NOTIFY_STOP; +} + +static struct notifier_block kgdb_notifier = { + .notifier_call = kgdb_mips_notify, +}; + +/* + * Handle the 's' and 'c' commands + */ +int kgdb_arch_handle_exception(int vector, int signo, int err_code, + char *remcom_in_buffer, char *remcom_out_buffer, + struct pt_regs *regs) +{ + char *ptr; + unsigned long address; + int cpu = smp_processor_id(); + + switch (remcom_in_buffer[0]) { + case 's': + case 'c': + /* handle the optional parameter */ + ptr = &remcom_in_buffer[1]; + if (kgdb_hex2long(&ptr, &address)) + regs->cp0_epc = address; + + atomic_set(&kgdb_cpu_doing_single_step, -1); + if (remcom_in_buffer[0] == 's') + if (kgdb_contthread) + atomic_set(&kgdb_cpu_doing_single_step, cpu); + + return 0; + } + + return -1; +} + +struct kgdb_arch arch_kgdb_ops = { +#ifdef CONFIG_CPU_LITTLE_ENDIAN + .gdb_bpt_instr = {0xd}, +#else /* ! CONFIG_CPU_LITTLE_ENDIAN */ + .gdb_bpt_instr = {0x00, 0x00, 0x00, 0x0d}, +#endif +}; + +/* + * We use kgdb_early_setup so that functions we need to call now don't + * cause trouble when called again later. + */ +int kgdb_arch_init(void) +{ + register_die_notifier(&kgdb_notifier); + return 0; +} + +/** + * kgdb_arch_exit - Perform any architecture specific uninitalization. + * + * This function will handle the uninitalization of any architecture + * specific callbacks, for dynamic registration and unregistration. + */ +void kgdb_arch_exit(void) +{ + unregister_die_notifier(&kgdb_notifier); +} --- a/arch/mips/kernel/traps.c +++ b/arch/mips/kernel/traps.c @@ -23,6 +23,8 @@ #include #include #include +#include +#include #include #include @@ -425,6 +427,10 @@ asmlinkage void do_be(struct pt_regs *re printk(KERN_ALERT "%s bus error, epc == %0*lx, ra == %0*lx\n", data ? "Data" : "Instruction", field, regs->cp0_epc, field, regs->regs[31]); + if (notify_die(DIE_OOPS, "bus error", regs, SIGBUS, 0, 0) + == NOTIFY_STOP) + return; + die_if_kernel("Oops", regs); force_sig(SIGBUS, current); } @@ -623,6 +629,9 @@ asmlinkage void do_fpe(struct pt_regs *r { siginfo_t info; + if (notify_die(DIE_FP, "FP exception", regs, SIGFPE, 0, 0) + == NOTIFY_STOP) + return; die_if_kernel("FP exception in kernel code", regs); if (fcr31 & FPU_CSR_UNI_X) { @@ -682,6 +691,9 @@ static void do_trap_or_bp(struct pt_regs siginfo_t info; char b[40]; + if (notify_die(DIE_TRAP, str, regs, code, 0, 0) == NOTIFY_STOP) + return; + /* * A short test says that IRIX 5.3 sends SIGTRAP for all trap * insns, even for trap and break codes that indicate arithmetic @@ -762,6 +774,10 @@ asmlinkage void do_ri(struct pt_regs *re unsigned int opcode = 0; int status = -1; + if (notify_die(DIE_RI, "RI Fault", regs, SIGSEGV, 0, 0) + == NOTIFY_STOP) + return; + die_if_kernel("Reserved instruction in kernel code", regs); if (unlikely(compute_return_epc(regs) < 0)) @@ -1537,6 +1553,11 @@ void __init trap_init(void) extern char except_vec4; unsigned long i; +#if defined(CONFIG_KGDB) + if (kgdb_early_setup) + return; /* Already done */ +#endif + if (cpu_has_veic || cpu_has_vint) ebase = (unsigned long) alloc_bootmem_low_pages(0x200 + VECTORSPACING*64); else --- /dev/null +++ b/include/asm-mips/kgdb.h @@ -0,0 +1,44 @@ +#ifdef __KERNEL__ +#ifndef _ASM_KGDB_H_ +#define _ASM_KGDB_H_ + +#include + +#ifndef __ASSEMBLY__ +#if (_MIPS_ISA == _MIPS_ISA_MIPS1) || (_MIPS_ISA == _MIPS_ISA_MIPS2) || \ + (_MIPS_ISA == _MIPS_ISA_MIPS32) + +#define KGDB_GDB_REG_SIZE 32 + +#elif (_MIPS_ISA == _MIPS_ISA_MIPS3) || (_MIPS_ISA == _MIPS_ISA_MIPS4) || \ + (_MIPS_ISA == _MIPS_ISA_MIPS64) + +#ifdef CONFIG_32BIT +#define KGDB_GDB_REG_SIZE 32 +#else /* CONFIG_CPU_32BIT */ +#define KGDB_GDB_REG_SIZE 64 +#endif +#else +#error "Need to set KGDB_GDB_REG_SIZE for MIPS ISA" +#endif /* _MIPS_ISA */ + +#define BUFMAX 2048 +#if (KGDB_GDB_REG_SIZE == 32) +#define NUMREGBYTES (90*sizeof(u32)) +#define NUMCRITREGBYTES (12*sizeof(u32)) +#else +#define NUMREGBYTES (90*sizeof(u64)) +#define NUMCRITREGBYTES (12*sizeof(u64)) +#endif +#define BREAK_INSTR_SIZE 4 +#define CACHE_FLUSH_IS_SAFE 0 + +extern void arch_kgdb_breakpoint(void); +extern int kgdb_early_setup; +extern void *saved_vectors[32]; +extern void handle_exception(struct pt_regs *regs); +extern void breakinst(void); + +#endif /* !__ASSEMBLY__ */ +#endif /* _ASM_KGDB_H_ */ +#endif /* __KERNEL__ */ --- a/arch/mips/Kconfig +++ b/arch/mips/Kconfig @@ -3,6 +3,7 @@ config MIPS default y select HAVE_IDE select HAVE_OPROFILE + select HAVE_ARCH_KGDB # Horrible source of confusion. Die, die, die ... select EMBEDDED select RTC_LIB --- a/include/asm-mips/kdebug.h +++ b/include/asm-mips/kdebug.h @@ -1 +1,13 @@ -#include +#ifndef _ASM_MIPS_KDEBUG_H +#define _ASM_MIPS_KDEBUG_H + +#include + +enum die_val { + DIE_OOPS = 1, + DIE_FP, + DIE_TRAP, + DIE_RI, +}; + +#endif /* _ASM_MIPS_KDEBUG_H */