Messages in this thread Patch in this message | | | Date | Fri, 6 Sep 2013 00:00:10 -0500 | From | Jason Wessel <> | Subject | Re: [PATCH 7/9] KGDB/KDB: add new system NMI entry code to KDB |
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On 09/05/2013 05:50 PM, Mike Travis wrote: > This patch adds a new "KDB_REASON" code (KDB_REASON_SYSTEM_NMI). This > is purely cosmetic to distinguish it from the other various reasons that > NMI may occur and are usually after an error occurred. Also the dumping > of registers is not done to more closely match what is displayed when KDB > is entered manually via the sysreq 'g' key.
This patch is not quite right. See below.
> > Signed-off-by: Mike Travis <travis@sgi.com> > Reviewed-by: Dimitri Sivanich <sivanich@sgi.com> > Reviewed-by: Hedi Berriche <hberrich@sgi.com> > --- > include/linux/kdb.h | 1 + > include/linux/kgdb.h | 1 + > kernel/debug/debug_core.c | 5 +++++ > kernel/debug/kdb/kdb_debugger.c | 5 ++++- > kernel/debug/kdb/kdb_main.c | 3 +++ > 5 files changed, 14 insertions(+), 1 deletion(-) > > --- linux.orig/include/linux/kdb.h > +++ linux/include/linux/kdb.h > @@ -109,6 +109,7 @@ typedef enum { > KDB_REASON_RECURSE, /* Recursive entry to kdb; > * regs probably valid */ > KDB_REASON_SSTEP, /* Single Step trap. - regs valid */ > + KDB_REASON_SYSTEM_NMI, /* In NMI due to SYSTEM cmd; regs valid */ > } kdb_reason_t; > > extern int kdb_trap_printk; > --- linux.orig/include/linux/kgdb.h > +++ linux/include/linux/kgdb.h > @@ -52,6 +52,7 @@ extern int kgdb_connected; > extern int kgdb_io_module_registered; > > extern atomic_t kgdb_setting_breakpoint; > +extern atomic_t kgdb_system_nmi;
We don't need extra atomics. You should add another variable to the kgdb_state which is processor specific in this case.
Better yet, just set the ks->err_code properly in your kgdb_nmicallin() or in the origination call to kgdb_nmicallback() from your nmi handler (remember I still have the question pending if we actually need kgdb_nmicallin() in the first place. You already did the work of adding another NMI type to the enum. We just need to use the ks->err_code variable as well.
> extern atomic_t kgdb_cpu_doing_single_step; > > extern struct task_struct *kgdb_usethread; > --- linux.orig/kernel/debug/debug_core.c > +++ linux/kernel/debug/debug_core.c > @@ -125,6 +125,7 @@ static atomic_t masters_in_kgdb; > static atomic_t slaves_in_kgdb; > static atomic_t kgdb_break_tasklet_var; > atomic_t kgdb_setting_breakpoint; > +atomic_t kgdb_system_nmi; > > struct task_struct *kgdb_usethread; > struct task_struct *kgdb_contthread; > @@ -760,7 +761,11 @@ int kgdb_nmicallin(int cpu, int trapnr, > > /* Indicate there are slaves waiting */ > kgdb_info[cpu].send_ready = send_ready; > + > + /* Use new reason code "SYSTEM_NMI" */ > + atomic_inc(&kgdb_system_nmi); > kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER); > + atomic_dec(&kgdb_system_nmi); > kgdb_do_roundup = save_kgdb_do_roundup; > kgdb_info[cpu].send_ready = NULL; > > --- linux.orig/kernel/debug/kdb/kdb_debugger.c > +++ linux/kernel/debug/kdb/kdb_debugger.c > @@ -69,7 +69,10 @@ int kdb_stub(struct kgdb_state *ks) > if (atomic_read(&kgdb_setting_breakpoint)) > reason = KDB_REASON_KEYBOARD; > > - if (in_nmi()) > + if (atomic_read(&kgdb_system_nmi)) > + reason = KDB_REASON_SYSTEM_NMI;
This would get changed to if (ks->err == KDB_REASON_SYSNMI && ks->signo == SIGTRAP) ....
Cheers, Jason.
> + > + else if (in_nmi()) > reason = KDB_REASON_NMI; > > for (i = 0, bp = kdb_breakpoints; i < KDB_MAXBPT; i++, bp++) { > --- linux.orig/kernel/debug/kdb/kdb_main.c > +++ linux/kernel/debug/kdb/kdb_main.c > @@ -1200,6 +1200,9 @@ static int kdb_local(kdb_reason_t reason > instruction_pointer(regs)); > kdb_dumpregs(regs); > break; > + case KDB_REASON_SYSTEM_NMI: > + kdb_printf("due to System NonMaskable Interrupt\n"); > + break; > case KDB_REASON_NMI: > kdb_printf("due to NonMaskable Interrupt @ " > kdb_machreg_fmt "\n", > > -- >
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