Messages in this thread Patch in this message | | | From | Jason Wessel <> | Subject | [PATCH 09/13] RFC ONLY - powerpc,kgdb: Introduce low level trap catching | Date | Fri, 8 May 2009 16:23:16 -0500 |
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This is a RFC patch. The work to possibly merge kdb and kgdb is being evaluated and this patch is considered only a proof of concept or prototype.
The only way the debugger can handle a trap in inside rcu_lock, notify_die, or atomic_notifier_call_chain without a recursive fault is to have a low level "first opportunity handler" low level program_check_exception() handler.
The other change here is to make sure that kgdb_handle_exception() is called with correct parameters when catching an oops, because kdb needs to know if the entry was an oops, single step, or breakpoint exception.
Signed-off-by: Jason Wessel <jason.wessel@windriver.com> --- arch/powerpc/kernel/kgdb.c | 7 +++++-- arch/powerpc/kernel/traps.c | 7 +++++++ lib/Kconfig.kgdb | 2 +- 3 files changed, 13 insertions(+), 3 deletions(-)
diff --git a/arch/powerpc/kernel/kgdb.c b/arch/powerpc/kernel/kgdb.c index e8207a3..d0ef25c 100644 --- a/arch/powerpc/kernel/kgdb.c +++ b/arch/powerpc/kernel/kgdb.c @@ -20,6 +20,7 @@ #include <linux/smp.h> #include <linux/signal.h> #include <linux/ptrace.h> +#include <linux/kdebug.h> #include <asm/current.h> #include <asm/processor.h> #include <asm/machdep.h> @@ -115,7 +116,9 @@ void kgdb_roundup_cpus(unsigned long flags) /* KGDB functions to use existing PowerPC64 hooks. */ static int kgdb_debugger(struct pt_regs *regs) { - return kgdb_handle_exception(0, computeSignal(TRAP(regs)), 0, regs); + if (kgdb_handle_exception(1, computeSignal(TRAP(regs)), DIE_OOPS, regs)) + return 0; + return 1; } static int kgdb_handle_breakpoint(struct pt_regs *regs) @@ -123,7 +126,7 @@ static int kgdb_handle_breakpoint(struct pt_regs *regs) if (user_mode(regs)) return 0; - if (kgdb_handle_exception(0, SIGTRAP, 0, regs) != 0) + if (kgdb_handle_exception(1, SIGTRAP, 0, regs) != 0) return 0; if (*(u32 *) (regs->nip) == *(u32 *) (&arch_kgdb_ops.gdb_bpt_instr)) diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c index 678fbff..ae409df 100644 --- a/arch/powerpc/kernel/traps.c +++ b/arch/powerpc/kernel/traps.c @@ -812,12 +812,19 @@ void __kprobes program_check_exception(struct pt_regs *regs) return; } if (reason & REASON_TRAP) { + +#ifdef CONFIG_KGDB_LOW_LEVEL_TRAP + if (debugger_bpt(regs)) + return; +#endif /* CONFIG_KGDB_LOW_LEVEL_TRAP */ /* trap exception */ if (notify_die(DIE_BPT, "breakpoint", regs, 5, 5, SIGTRAP) == NOTIFY_STOP) return; +#ifndef CONFIG_KGDB_LOW_LEVEL_TRAP if (debugger_bpt(regs)) return; +#endif /* ! CONFIG_KGDB_LOW_LEVEL_TRAP */ if (!(regs->msr & MSR_PR) && /* not user-mode */ report_bug(regs->nip, regs) == BUG_TRAP_TYPE_WARN) { diff --git a/lib/Kconfig.kgdb b/lib/Kconfig.kgdb index 617f797..a2f63be 100644 --- a/lib/Kconfig.kgdb +++ b/lib/Kconfig.kgdb @@ -59,7 +59,7 @@ config KGDB_TESTS_BOOT_STRING config KGDB_LOW_LEVEL_TRAP bool "KGDB: Allow debugging with traps in notifiers" - depends on X86 + depends on X86 || PPC default n help This will add an extra call back to kgdb for the breakpoint -- 1.6.3.rc0.1.gf800
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