Messages in this thread | | | Date | Tue, 24 Jun 2014 12:22:50 -0400 (EDT) | From | Nicolas Pitre <> | Subject | Re: [PATCH v6 4/4] ARM: Add KGDB/KDB FIQ debugger generic code |
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On Tue, 24 Jun 2014, Daniel Thompson wrote:
> From: Anton Vorontsov <anton.vorontsov@linaro.org> > > The FIQ debugger may be used to debug situations when the kernel stuck > in uninterruptable sections, e.g. the kernel infinitely loops or > deadlocked in an interrupt or with interrupts disabled. > > By default KGDB FIQ is disabled in runtime, but can be enabled with > kgdb_fiq.enable=1 kernel command line option. > > Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org> > Signed-off-by: John Stultz <john.stultz@linaro.org> > Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org> > Cc: Russell King <linux@arm.linux.org.uk> > Cc: Ben Dooks <ben.dooks@codethink.co.uk> > Cc: Dave Martin <Dave.Martin@arm.com> > --- > arch/arm/Kconfig | 2 + > arch/arm/Kconfig.debug | 18 ++++++ > arch/arm/include/asm/kgdb.h | 7 +++ > arch/arm/kernel/Makefile | 1 + > arch/arm/kernel/kgdb_fiq.c | 124 +++++++++++++++++++++++++++++++++++++++ > arch/arm/kernel/kgdb_fiq_entry.S | 87 +++++++++++++++++++++++++++ > 6 files changed, 239 insertions(+) > create mode 100644 arch/arm/kernel/kgdb_fiq.c > create mode 100644 arch/arm/kernel/kgdb_fiq_entry.S
[...]
> +static long kgdb_fiq_setup_stack(void *info) > +{ > + struct pt_regs regs; > + > + regs.ARM_sp = __get_free_pages(GFP_KERNEL, THREAD_SIZE_ORDER) + > + THREAD_START_SP; > + WARN_ON(!regs.ARM_sp);
Isn't this rather fatal if you can't allocate any stack? Why not using BUG_ON(), or better yet propagate a proper error code back?
> + > + set_fiq_regs(®s); > + return 0; > +} > + > +/** > + * kgdb_fiq_enable_nmi - Manage NMI-triggered entry to KGDB > + * @on: Flag to either enable or disable an NMI > + * > + * This function manages NMIs that usually cause KGDB to enter. That is, not > + * all NMIs should be enabled or disabled, but only those that issue > + * kgdb_handle_exception(). > + * > + * The call counts disable requests, and thus allows to nest disables. But > + * trying to enable already enabled NMI is an error. > + */ > +static void kgdb_fiq_enable_nmi(bool on) > +{ > + static atomic_t cnt; > + int ret; > + > + ret = atomic_add_return(on ? 1 : -1, &cnt); > + if (ret > 1 && on) { > + /* > + * There should be only one instance that calls this function > + * in "enable, disable" order. All other users must call > + * disable first, then enable. If not, something is wrong. > + */ > + WARN_ON(1); > + return; > + }
Minor style suggestion:
/* * There should be only one instance that calls this function * in "enable, disable" order. All other users must call * disable first, then enable. If not, something is wrong. */ if (WARN_ON(ret > 1 && on)) return;
Other than that...
Acked-by: Nicolas Pitre <nico@linaro.org>
Nicolas
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