The kernel debugger can operate well before mm_init(), but the x86 hardware breakpoint code which uses the perf api requires that the kernel allocators are initialized.
This means the kernel debug core needs to provide an optional arch specific call back to allow the initialization functions to run after the kernel has been further initialized. The kdb shell already had a similar restriction with an early initialization and late initialization. The kdb_init() was moved into the debug core's version of the late init which is called dbg_late_init(); CC: [email protected] Signed-off-by: Jason Wessel <[email protected]> --- arch/x86/kernel/kgdb.c | 17 ++++++++++------- include/linux/kgdb.h | 14 ++++++++++++++ init/main.c | 4 ++-- kernel/debug/debug_core.c | 16 ++++++++++++++++ 4 files changed, 42 insertions(+), 9 deletions(-) diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c index 3b762bc..896874a 100644 --- a/arch/x86/kernel/kgdb.c +++ b/arch/x86/kernel/kgdb.c @@ -596,14 +596,15 @@ static struct notifier_block kgdb_notifier = { */ int kgdb_arch_init(void) { + return register_die_notifier(&kgdb_notifier); +} + +void kgdb_arch_late(void) +{ int i, cpu; - int ret; struct perf_event_attr attr; struct perf_event **pevent; - ret = register_die_notifier(&kgdb_notifier); - if (ret != 0) - return ret; /* * Pre-allocate the hw breakpoint structions in the non-atomic * portion of kgdb because this operation requires mutexs to @@ -615,12 +616,15 @@ int kgdb_arch_init(void) attr.bp_type = HW_BREAKPOINT_W; attr.disabled = 1; for (i = 0; i < 4; i++) { + if (breakinfo[i].pev) + continue; breakinfo[i].pev = register_wide_hw_breakpoint(&attr, NULL); if (IS_ERR(breakinfo[i].pev)) { - printk(KERN_ERR "kgdb: Could not allocate hw breakpoints\n"); + printk(KERN_ERR "kgdb: Could not allocate hw" + "breakpoints\nDisabling the kernel debugger\n"); breakinfo[i].pev = NULL; kgdb_arch_exit(); - return -1; + return; } for_each_online_cpu(cpu) { pevent = per_cpu_ptr(breakinfo[i].pev, cpu); @@ -631,7 +635,6 @@ int kgdb_arch_init(void) } } } - return ret; } /** diff --git a/include/linux/kgdb.h b/include/linux/kgdb.h index 6c784ab..9340f34 100644 --- a/include/linux/kgdb.h +++ b/include/linux/kgdb.h @@ -208,6 +208,17 @@ extern int kgdb_arch_set_breakpoint(unsigned long addr, char *saved_instr); extern int kgdb_arch_remove_breakpoint(unsigned long addr, char *bundle); /** + * kgdb_arch_late - Perform any architecture specific initalization. + * + * This function will handle the late initalization of any + * architecture specific callbacks. This is an optional function for + * handling things like late initialization of hw breakpoints. The + * default implementation does nothing. + */ +extern void kgdb_arch_late(void); + + +/** * struct kgdb_arch - Describe architecture specific values. * @gdb_bpt_instr: The instruction to trigger a breakpoint. * @flags: Flags for the breakpoint, currently just %KGDB_HW_BREAKPOINT. @@ -285,7 +296,10 @@ extern int kgdb_single_step; extern atomic_t kgdb_active; #define in_dbg_master() \ (raw_smp_processor_id() == atomic_read(&kgdb_active)) +extern bool dbg_is_early; +extern void __init dbg_late_init(void); #else /* ! CONFIG_KGDB */ #define in_dbg_master() (0) +#define dbg_late_init() #endif /* ! CONFIG_KGDB */ #endif /* _KGDB_H_ */ diff --git a/init/main.c b/init/main.c index 9d415a1..1839e3f 100644 --- a/init/main.c +++ b/init/main.c @@ -63,7 +63,7 @@ #include <linux/sched.h> #include <linux/signal.h> #include <linux/idr.h> -#include <linux/kdb.h> +#include <linux/kgdb.h> #include <linux/ftrace.h> #include <linux/async.h> #include <linux/kmemcheck.h> @@ -660,7 +660,7 @@ asmlinkage void __init start_kernel(void) key_init(); radix_tree_init(); security_init(); - kdb_init(KDB_INIT_FULL); + dbg_late_init(); vfs_caches_init(totalram_pages); signals_init(); /* rootfs populating might need page-writeback */ diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c index 3d36d9e..e7a4d9b 100644 --- a/kernel/debug/debug_core.c +++ b/kernel/debug/debug_core.c @@ -78,6 +78,8 @@ static DEFINE_SPINLOCK(kgdb_registration_lock); static int kgdb_con_registered; /* determine if kgdb console output should be used */ static int kgdb_use_con; +/* Flag for alternate operations for early debugging */ +bool dbg_is_early = true; /* Next cpu to become the master debug core */ int dbg_switch_cpu; @@ -777,11 +779,25 @@ static struct notifier_block kgdb_panic_event_nb = { .priority = INT_MAX, }; +void __weak kgdb_arch_late(void) +{ +} + +void __init dbg_late_init(void) +{ + dbg_is_early = false; + if (kgdb_io_module_registered) + kgdb_arch_late(); + kdb_init(KDB_INIT_FULL); +} + static void kgdb_register_callbacks(void) { if (!kgdb_io_module_registered) { kgdb_io_module_registered = 1; kgdb_arch_init(); + if (!dbg_is_early) + kgdb_arch_late(); atomic_notifier_chain_register(&panic_notifier_list, &kgdb_panic_event_nb); #ifdef CONFIG_MAGIC_SYSRQ -- 1.6.4.rc1 ------------------------------------------------------------------------------ Download Intel® Parallel Studio Eval Try the new software tools for yourself. Speed compiling, find bugs proactively, and fine-tune applications for parallel performance. See why Intel Parallel Studio got high marks during beta. http://p.sf.net/sfu/intel-sw-dev _______________________________________________ Kgdb-bugreport mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/kgdb-bugreport
