| Message ID | 1448335593-27862-1-git-send-email-ruscur@russell.cc (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
On 11/24/15, Russell Currey <ruscur@russell.cc> wrote: > On BMC machines, console output is controlled by the OPAL firmware and is > only flushed when its pollers are called. When the kernel is in a panic > state, it no longer calls these pollers and thus console output does not > completely flush, causing some output from the panic to be lost. > > This patch adds a new kmsg_dumper which gets called at panic time to ensure > panic output is not lost. It accomplishes this by calling > OPAL_CONSOLE_FLUSH > in the OPAL API, and if that is not available, the pollers are called enough > times to (hopefully) completely flush the buffer. > > Signed-off-by: Russell Currey <ruscur@russell.cc> Some minor nits below. > --- > A patch to add the preferred OPAL call for flushing the console buffer, > OPAL_CONSOLE_FLUSH, was recently sent upstream to Skiboot. You can track > its progress here: https://patchwork.ozlabs.org/patch/547379/ > --- > arch/powerpc/include/asm/opal-api.h | 3 +- > arch/powerpc/include/asm/opal.h | 3 ++ > arch/powerpc/platforms/powernv/Makefile | 1 + > arch/powerpc/platforms/powernv/opal-kmsg.c | 70 > ++++++++++++++++++++++++++ > arch/powerpc/platforms/powernv/opal-wrappers.S | 1 + > arch/powerpc/platforms/powernv/opal.c | 3 ++ > 6 files changed, 80 insertions(+), 1 deletion(-) > create mode 100644 arch/powerpc/platforms/powernv/opal-kmsg.c > > diff --git a/arch/powerpc/include/asm/opal-api.h > b/arch/powerpc/include/asm/opal-api.h > index 8374afe..f8faaae 100644 > --- a/arch/powerpc/include/asm/opal-api.h > +++ b/arch/powerpc/include/asm/opal-api.h > @@ -157,7 +157,8 @@ > #define OPAL_LEDS_GET_INDICATOR 114 > #define OPAL_LEDS_SET_INDICATOR 115 > #define OPAL_CEC_REBOOT2 116 > -#define OPAL_LAST 116 > +#define OPAL_CONSOLE_FLUSH 117 > +#define OPAL_LAST 117 > > /* Device tree flags */ > > diff --git a/arch/powerpc/include/asm/opal.h > b/arch/powerpc/include/asm/opal.h > index 8001159..a5fd407 100644 > --- a/arch/powerpc/include/asm/opal.h > +++ b/arch/powerpc/include/asm/opal.h > @@ -35,6 +35,7 @@ int64_t opal_console_read(int64_t term_number, __be64 > *length, > uint8_t *buffer); > int64_t opal_console_write_buffer_space(int64_t term_number, > __be64 *length); > +void opal_console_flush(void); > int64_t opal_rtc_read(__be32 *year_month_day, > __be64 *hour_minute_second_millisecond); > int64_t opal_rtc_write(uint32_t year_month_day, > @@ -262,6 +263,8 @@ extern int opal_resync_timebase(void); > > extern void opal_lpc_init(void); > > +extern void opal_kmsg_init(void); > + > extern int opal_event_request(unsigned int opal_event_nr); > > struct opal_sg_list *opal_vmalloc_to_sg_list(void *vmalloc_addr, > diff --git a/arch/powerpc/platforms/powernv/Makefile > b/arch/powerpc/platforms/powernv/Makefile > index 1c8cdb6..b9de7ef 100644 > --- a/arch/powerpc/platforms/powernv/Makefile > +++ b/arch/powerpc/platforms/powernv/Makefile > @@ -2,6 +2,7 @@ obj-y += setup.o opal-wrappers.o opal.o opal-async.o > idle.o > obj-y += opal-rtc.o opal-nvram.o opal-lpc.o opal-flash.o > obj-y += rng.o opal-elog.o opal-dump.o opal-sysparam.o opal-sensor.o > obj-y += opal-msglog.o opal-hmi.o opal-power.o opal-irqchip.o > +obj-y += opal-kmsg.o > > obj-$(CONFIG_SMP) += smp.o subcore.o subcore-asm.o > obj-$(CONFIG_PCI) += pci.o pci-p5ioc2.o pci-ioda.o > diff --git a/arch/powerpc/platforms/powernv/opal-kmsg.c > b/arch/powerpc/platforms/powernv/opal-kmsg.c > new file mode 100644 > index 0000000..904f123 > --- /dev/null > +++ b/arch/powerpc/platforms/powernv/opal-kmsg.c > @@ -0,0 +1,70 @@ > +/* > + * kmsg dumper that ensures the OPAL console fully flushes panic messages > + * > + * Author: Russell Currey <ruscur@russell.cc> > + * > + * Copyright 2015 IBM Corporation. > + * > + * This program is free software; you can redistribute it and/or modify it > + * under the terms of the GNU General Public License as published by the > + * Free Software Foundation; either version 2 of the License, or (at your > + * option) any later version. > + */ > + > +#include <linux/kmsg_dump.h> > + > +#include <asm/opal.h> > +#include <asm/opal-api.h> > + > +/* > + * Console output is controlled by OPAL firmware. The kernel regularly > calls > + * OPAL_POLL_EVENTS, which flushes some console output. In a panic state, > + * however, the kernel no longer calls OPAL_POLL_EVENTS and the panic > message > + * may not be completely printed. This function does not actually dump the > + * message, it just ensures that OPAL completely flushes the console > buffer. > + */ > +static void force_opal_console_flush(struct kmsg_dumper *dumper, > + enum kmsg_dump_reason reason) > +{ > + int i; > + > + /* > + * Outside of a panic context the pollers will continue to run, > + * so we don't need to do any special flushing. > + */ > + if (reason != KMSG_DUMP_PANIC) { > + return; > + } We don't need the brackets with one-line block > + > + if (opal_check_token(OPAL_CONSOLE_FLUSH)) { > + opal_console_flush(); > + } else { > + /* > + * If OPAL_CONSOLE_FLUSH is not implemented in the firmware, > + * the console can still be flushed by calling the polling > + * function enough times to flush the buffer. We don't know > + * how much output still needs to be flushed, but we can be > + * generous since the kernel is in panic and doesn't need > + * to do much else. > + */ > + printk(KERN_NOTICE "opal: OPAL_CONSOLE_FLUSH missing.\n"); > + for (i = 0; i < 1024; i++) { > + opal_poll_events(NULL); > + } > + } > +} > + > +static struct kmsg_dumper opal_kmsg_dumper = { > + .dump = force_opal_console_flush > +}; > + > +void __init opal_kmsg_init(void) > +{ > + int rc; > + > + /* Add our dumper to the list */ > + rc = kmsg_dump_register(&opal_kmsg_dumper); > + if (rc != 0) { > + pr_err("opal: kmsg_dump_register failed; returned %d\n", rc); > + } ditto. > +} > diff --git a/arch/powerpc/platforms/powernv/opal-wrappers.S > b/arch/powerpc/platforms/powernv/opal-wrappers.S > index b7a464f..e45b88a 100644 > --- a/arch/powerpc/platforms/powernv/opal-wrappers.S > +++ b/arch/powerpc/platforms/powernv/opal-wrappers.S > @@ -301,3 +301,4 @@ OPAL_CALL(opal_flash_erase, OPAL_FLASH_ERASE); > OPAL_CALL(opal_prd_msg, OPAL_PRD_MSG); > OPAL_CALL(opal_leds_get_ind, OPAL_LEDS_GET_INDICATOR); > OPAL_CALL(opal_leds_set_ind, OPAL_LEDS_SET_INDICATOR); > +OPAL_CALL(opal_console_flush, OPAL_CONSOLE_FLUSH); > diff --git a/arch/powerpc/platforms/powernv/opal.c > b/arch/powerpc/platforms/powernv/opal.c > index 4296d55..a94a85c 100644 > --- a/arch/powerpc/platforms/powernv/opal.c > +++ b/arch/powerpc/platforms/powernv/opal.c > @@ -758,6 +758,9 @@ static int __init opal_init(void) > opal_pdev_init(opal_node, "ibm,opal-flash"); > opal_pdev_init(opal_node, "ibm,opal-prd"); > > + /* Initialise OPAL kmsg dumper for flushing console on panic */ > + opal_kmsg_init(); > + > return 0; > } > machine_subsys_initcall(powernv, opal_init); > -- > 2.6.2 > > _______________________________________________ > Linuxppc-dev mailing list > Linuxppc-dev@lists.ozlabs.org > https://lists.ozlabs.org/listinfo/linuxppc-dev
diff --git a/arch/powerpc/include/asm/opal-api.h b/arch/powerpc/include/asm/opal-api.h index 8374afe..f8faaae 100644 --- a/arch/powerpc/include/asm/opal-api.h +++ b/arch/powerpc/include/asm/opal-api.h @@ -157,7 +157,8 @@ #define OPAL_LEDS_GET_INDICATOR 114 #define OPAL_LEDS_SET_INDICATOR 115 #define OPAL_CEC_REBOOT2 116 -#define OPAL_LAST 116 +#define OPAL_CONSOLE_FLUSH 117 +#define OPAL_LAST 117 /* Device tree flags */ diff --git a/arch/powerpc/include/asm/opal.h b/arch/powerpc/include/asm/opal.h index 8001159..a5fd407 100644 --- a/arch/powerpc/include/asm/opal.h +++ b/arch/powerpc/include/asm/opal.h @@ -35,6 +35,7 @@ int64_t opal_console_read(int64_t term_number, __be64 *length, uint8_t *buffer); int64_t opal_console_write_buffer_space(int64_t term_number, __be64 *length); +void opal_console_flush(void); int64_t opal_rtc_read(__be32 *year_month_day, __be64 *hour_minute_second_millisecond); int64_t opal_rtc_write(uint32_t year_month_day, @@ -262,6 +263,8 @@ extern int opal_resync_timebase(void); extern void opal_lpc_init(void); +extern void opal_kmsg_init(void); + extern int opal_event_request(unsigned int opal_event_nr); struct opal_sg_list *opal_vmalloc_to_sg_list(void *vmalloc_addr, diff --git a/arch/powerpc/platforms/powernv/Makefile b/arch/powerpc/platforms/powernv/Makefile index 1c8cdb6..b9de7ef 100644 --- a/arch/powerpc/platforms/powernv/Makefile +++ b/arch/powerpc/platforms/powernv/Makefile @@ -2,6 +2,7 @@ obj-y += setup.o opal-wrappers.o opal.o opal-async.o idle.o obj-y += opal-rtc.o opal-nvram.o opal-lpc.o opal-flash.o obj-y += rng.o opal-elog.o opal-dump.o opal-sysparam.o opal-sensor.o obj-y += opal-msglog.o opal-hmi.o opal-power.o opal-irqchip.o +obj-y += opal-kmsg.o obj-$(CONFIG_SMP) += smp.o subcore.o subcore-asm.o obj-$(CONFIG_PCI) += pci.o pci-p5ioc2.o pci-ioda.o diff --git a/arch/powerpc/platforms/powernv/opal-kmsg.c b/arch/powerpc/platforms/powernv/opal-kmsg.c new file mode 100644 index 0000000..904f123 --- /dev/null +++ b/arch/powerpc/platforms/powernv/opal-kmsg.c @@ -0,0 +1,70 @@ +/* + * kmsg dumper that ensures the OPAL console fully flushes panic messages + * + * Author: Russell Currey <ruscur@russell.cc> + * + * Copyright 2015 IBM Corporation. + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License as published by the + * Free Software Foundation; either version 2 of the License, or (at your + * option) any later version. + */ + +#include <linux/kmsg_dump.h> + +#include <asm/opal.h> +#include <asm/opal-api.h> + +/* + * Console output is controlled by OPAL firmware. The kernel regularly calls + * OPAL_POLL_EVENTS, which flushes some console output. In a panic state, + * however, the kernel no longer calls OPAL_POLL_EVENTS and the panic message + * may not be completely printed. This function does not actually dump the + * message, it just ensures that OPAL completely flushes the console buffer. + */ +static void force_opal_console_flush(struct kmsg_dumper *dumper, + enum kmsg_dump_reason reason) +{ + int i; + + /* + * Outside of a panic context the pollers will continue to run, + * so we don't need to do any special flushing. + */ + if (reason != KMSG_DUMP_PANIC) { + return; + } + + if (opal_check_token(OPAL_CONSOLE_FLUSH)) { + opal_console_flush(); + } else { + /* + * If OPAL_CONSOLE_FLUSH is not implemented in the firmware, + * the console can still be flushed by calling the polling + * function enough times to flush the buffer. We don't know + * how much output still needs to be flushed, but we can be + * generous since the kernel is in panic and doesn't need + * to do much else. + */ + printk(KERN_NOTICE "opal: OPAL_CONSOLE_FLUSH missing.\n"); + for (i = 0; i < 1024; i++) { + opal_poll_events(NULL); + } + } +} + +static struct kmsg_dumper opal_kmsg_dumper = { + .dump = force_opal_console_flush +}; + +void __init opal_kmsg_init(void) +{ + int rc; + + /* Add our dumper to the list */ + rc = kmsg_dump_register(&opal_kmsg_dumper); + if (rc != 0) { + pr_err("opal: kmsg_dump_register failed; returned %d\n", rc); + } +} diff --git a/arch/powerpc/platforms/powernv/opal-wrappers.S b/arch/powerpc/platforms/powernv/opal-wrappers.S index b7a464f..e45b88a 100644 --- a/arch/powerpc/platforms/powernv/opal-wrappers.S +++ b/arch/powerpc/platforms/powernv/opal-wrappers.S @@ -301,3 +301,4 @@ OPAL_CALL(opal_flash_erase, OPAL_FLASH_ERASE); OPAL_CALL(opal_prd_msg, OPAL_PRD_MSG); OPAL_CALL(opal_leds_get_ind, OPAL_LEDS_GET_INDICATOR); OPAL_CALL(opal_leds_set_ind, OPAL_LEDS_SET_INDICATOR); +OPAL_CALL(opal_console_flush, OPAL_CONSOLE_FLUSH); diff --git a/arch/powerpc/platforms/powernv/opal.c b/arch/powerpc/platforms/powernv/opal.c index 4296d55..a94a85c 100644 --- a/arch/powerpc/platforms/powernv/opal.c +++ b/arch/powerpc/platforms/powernv/opal.c @@ -758,6 +758,9 @@ static int __init opal_init(void) opal_pdev_init(opal_node, "ibm,opal-flash"); opal_pdev_init(opal_node, "ibm,opal-prd"); + /* Initialise OPAL kmsg dumper for flushing console on panic */ + opal_kmsg_init(); + return 0; } machine_subsys_initcall(powernv, opal_init);
On BMC machines, console output is controlled by the OPAL firmware and is only flushed when its pollers are called. When the kernel is in a panic state, it no longer calls these pollers and thus console output does not completely flush, causing some output from the panic to be lost. This patch adds a new kmsg_dumper which gets called at panic time to ensure panic output is not lost. It accomplishes this by calling OPAL_CONSOLE_FLUSH in the OPAL API, and if that is not available, the pollers are called enough times to (hopefully) completely flush the buffer. Signed-off-by: Russell Currey <ruscur@russell.cc> --- A patch to add the preferred OPAL call for flushing the console buffer, OPAL_CONSOLE_FLUSH, was recently sent upstream to Skiboot. You can track its progress here: https://patchwork.ozlabs.org/patch/547379/ --- arch/powerpc/include/asm/opal-api.h | 3 +- arch/powerpc/include/asm/opal.h | 3 ++ arch/powerpc/platforms/powernv/Makefile | 1 + arch/powerpc/platforms/powernv/opal-kmsg.c | 70 ++++++++++++++++++++++++++ arch/powerpc/platforms/powernv/opal-wrappers.S | 1 + arch/powerpc/platforms/powernv/opal.c | 3 ++ 6 files changed, 80 insertions(+), 1 deletion(-) create mode 100644 arch/powerpc/platforms/powernv/opal-kmsg.c