On Tue, May 12, 2020 at 06:35:04PM -0500, Tyler Hicks wrote: > On 2020-05-06 14:15:21, Kees Cook wrote: > > From: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx> > > > > Now that pstore_register() can correctly pass max_reason to the kmesg > > dump facility, introduce a new "max_reason" module parameter and > > "max-reason" Device Tree field. > > > > The "dump_oops" module parameter and "dump-oops" Device > > Tree field are now considered deprecated, but are now automatically > > converted to their corresponding max_reason values when present, though > > the new max_reason setting has precedence. > > > > For struct ramoops_platform_data, the "dump_oops" member is entirely > > replaced by a new "max_reason" member, with the only existing user > > updated in place. > > > > Additionally remove the "reason" filter logic from ramoops_pstore_write(), > > as that is not specifically needed anymore, though technically > > this is a change in behavior for any ramoops users also setting the > > printk.always_kmsg_dump boot param, which will cause ramoops to behave as > > if max_reason was set to KMSG_DUMP_MAX. > > > > Signed-off-by: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx> > > Link: https://lore.kernel.org/r/20200505154510.93506-4-pasha.tatashin@xxxxxxxxxx > > Link: https://lore.kernel.org/r/20200505154510.93506-5-pasha.tatashin@xxxxxxxxxx > > Co-developed-by: Kees Cook <keescook@xxxxxxxxxxxx> > > Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> > > --- > > Documentation/admin-guide/ramoops.rst | 14 +++++-- > > drivers/platform/chrome/chromeos_pstore.c | 2 +- > > fs/pstore/ram.c | 51 +++++++++++++++-------- > > include/linux/pstore_ram.h | 2 +- > > 4 files changed, 45 insertions(+), 24 deletions(-) > > > > diff --git a/Documentation/admin-guide/ramoops.rst b/Documentation/admin-guide/ramoops.rst > > index 6dbcc5481000..a60a96218ba9 100644 > > --- a/Documentation/admin-guide/ramoops.rst > > +++ b/Documentation/admin-guide/ramoops.rst > > @@ -32,11 +32,17 @@ memory to be mapped strongly ordered, and atomic operations on strongly ordered > > memory are implementation defined, and won't work on many ARMs such as omaps. > > > > The memory area is divided into ``record_size`` chunks (also rounded down to > > -power of two) and each oops/panic writes a ``record_size`` chunk of > > +power of two) and each kmesg dump writes a ``record_size`` chunk of > > information. > > > > -Dumping both oopses and panics can be done by setting 1 in the ``dump_oops`` > > -variable while setting 0 in that variable dumps only the panics. > > +Limiting which kinds of kmsg dumps are stored can be controlled via > > +the ``max_reason`` value, as defined in include/linux/kmsg_dump.h's > > +``enum kmsg_dump_reason``. For example, to store both Oopses and Panics, > > +``max_reason`` should be set to 2 (KMSG_DUMP_OOPS), to store only Panics > > +``max_reason`` should be set to 1 (KMSG_DUMP_PANIC). Setting this to 0 > > +(KMSG_DUMP_UNDEF), means the reason filtering will be controlled by the > > +``printk.always_kmsg_dump`` boot param: if unset, it'll be KMSG_DUMP_OOPS, > > +otherwise KMSG_DUMP_MAX. > > > > The module uses a counter to record multiple dumps but the counter gets reset > > on restart (i.e. new dumps after the restart will overwrite old ones). > > @@ -90,7 +96,7 @@ Setting the ramoops parameters can be done in several different manners: > > .mem_address = <...>, > > .mem_type = <...>, > > .record_size = <...>, > > - .dump_oops = <...>, > > + .max_reason = <...>, > > .ecc = <...>, > > }; > > > > diff --git a/drivers/platform/chrome/chromeos_pstore.c b/drivers/platform/chrome/chromeos_pstore.c > > index d13770785fb5..fa51153688b4 100644 > > --- a/drivers/platform/chrome/chromeos_pstore.c > > +++ b/drivers/platform/chrome/chromeos_pstore.c > > @@ -57,7 +57,7 @@ static struct ramoops_platform_data chromeos_ramoops_data = { > > .record_size = 0x40000, > > .console_size = 0x20000, > > .ftrace_size = 0x20000, > > - .dump_oops = 1, > > + .max_reason = KMSG_DUMP_OOPS, > > }; > > > > static struct platform_device chromeos_ramoops = { > > diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c > > index c2f76b650f91..b8dac1d04e96 100644 > > --- a/fs/pstore/ram.c > > +++ b/fs/pstore/ram.c > > @@ -57,10 +57,15 @@ module_param(mem_type, uint, 0600); > > MODULE_PARM_DESC(mem_type, > > "set to 1 to try to use unbuffered memory (default 0)"); > > > > -static int dump_oops = 1; > > -module_param(dump_oops, int, 0600); > > +static int ramoops_dump_oops = -1; > > +module_param_named(dump_oops, ramoops_dump_oops, int, 0400); > > MODULE_PARM_DESC(dump_oops, > > - "set to 1 to dump oopses, 0 to only dump panics (default 1)"); > > + "set to 1 to dump oopses & panics, 0 to only dump panics (deprecated: use max_reason instead)"); > > + > > +static int ramoops_max_reason = KMESG_DUMP_OOPS; > > +module_param_named(max_reason, ramoops_max_reason, int, 0400); > > +MODULE_PARM_DESC(max_reason, > > + "maximum reason for kmsg dump (default 2: Oops and Panic) "); > > > > static int ramoops_ecc; > > module_param_named(ecc, ramoops_ecc, int, 0600); > > @@ -81,7 +86,6 @@ struct ramoops_context { > > size_t console_size; > > size_t ftrace_size; > > size_t pmsg_size; > > - int dump_oops; > > u32 flags; > > struct persistent_ram_ecc_info ecc_info; > > unsigned int max_dump_cnt; > > @@ -382,16 +386,14 @@ static int notrace ramoops_pstore_write(struct pstore_record *record) > > return -EINVAL; > > > > /* > > - * Out of the various dmesg dump types, ramoops is currently designed > > - * to only store crash logs, rather than storing general kernel logs. > > + * We could filter on record->reason here if we wanted to (which > > + * would duplicate what happened before the "max_reason" setting > > + * was added), but that would defeat the purpose of a system > > + * changing printk.always_kmsg_dump, so instead log everything that > > + * the kmsg dumper sends us, since it should be doing the filtering > > + * based on the combination of printk.always_kmsg_dump and our > > + * requested "max_reason". > > */ > > - if (record->reason != KMSG_DUMP_OOPS && > > - record->reason != KMSG_DUMP_PANIC) > > - return -EINVAL; > > - > > - /* Skip Oopes when configured to do so. */ > > - if (record->reason == KMSG_DUMP_OOPS && !cxt->dump_oops) > > - return -EINVAL; > > > > /* > > * Explicitly only take the first part of any new crash. > > @@ -692,7 +694,14 @@ static int ramoops_parse_dt(struct platform_device *pdev, > > pdata->mem_size = resource_size(res); > > pdata->mem_address = res->start; > > pdata->mem_type = of_property_read_bool(of_node, "unbuffered"); > > - pdata->dump_oops = !of_property_read_bool(of_node, "no-dump-oops"); > > + /* > > + * Setting "no-dump-oops" is deprecated and will be ignored if > > + * "max_reason" is also specified. > > + */ > > + if (of_property_read_bool(of_node, "no-dump-oops")) > > + pdata->max_reason = KMSG_DUMP_PANIC; > > + else > > + pdata->max_reason = KMSG_DUMP_OOPS; > > > > #define parse_size(name, field, default_value) { \ > > ret = ramoops_parse_dt_size(pdev, name, default_value, \ > > @@ -708,6 +717,7 @@ static int ramoops_parse_dt(struct platform_device *pdev, > > parse_size("pmsg-size", pdata->pmsg_size, 0); > > parse_size("ecc-size", pdata->ecc_info.ecc_size, 0); > > parse_size("flags", pdata->flags, 0); > > + parse_size("max-reason", pdata->max_reason, pdata->max_reason); > > > > #undef parse_size > > > > @@ -791,7 +801,6 @@ static int ramoops_probe(struct platform_device *pdev) > > cxt->console_size = pdata->console_size; > > cxt->ftrace_size = pdata->ftrace_size; > > cxt->pmsg_size = pdata->pmsg_size; > > - cxt->dump_oops = pdata->dump_oops; > > cxt->flags = pdata->flags; > > cxt->ecc_info = pdata->ecc_info; > > > > @@ -834,8 +843,10 @@ static int ramoops_probe(struct platform_device *pdev) > > * the single region size is how to check. > > */ > > cxt->pstore.flags = 0; > > - if (cxt->max_dump_cnt) > > + if (cxt->max_dump_cnt) { > > cxt->pstore.flags |= PSTORE_FLAGS_DMESG; > > + cxt->pstore.max_reason = pdata->max_reason; > > + } > > if (cxt->console_size) > > cxt->pstore.flags |= PSTORE_FLAGS_CONSOLE; > > if (cxt->max_ftrace_cnt) > > @@ -871,7 +882,7 @@ static int ramoops_probe(struct platform_device *pdev) > > mem_size = pdata->mem_size; > > mem_address = pdata->mem_address; > > record_size = pdata->record_size; > > - dump_oops = pdata->dump_oops; > > + ramoops_max_reason = pdata->max_reason; > > ramoops_console_size = pdata->console_size; > > ramoops_pmsg_size = pdata->pmsg_size; > > ramoops_ftrace_size = pdata->ftrace_size; > > @@ -954,7 +965,11 @@ static void __init ramoops_register_dummy(void) > > pdata.console_size = ramoops_console_size; > > pdata.ftrace_size = ramoops_ftrace_size; > > pdata.pmsg_size = ramoops_pmsg_size; > > - pdata.dump_oops = dump_oops; > > + /* Parse deprecated module param "dump_oops" into "max_reason". */ > > + if (ramoops_dump_oops != -1) > > + pdata.max_reason = ramoops_dump_oops ? KMSG_DUMP_OOPS > > + : KMSG_DUMP_PANIC; > > + pdata.max_reason = ramoops_max_reason; > > This isn't quite right. We're conditionally assigning pdata.max_reason > and then immediately re-assigning it. > > IIUC, we're just missing an else block and it should look like this: > > /* Parse deprecated module param "dump_oops" into "max_reason". */ > if (ramoops_dump_oops != -1) > pdata.max_reason = ramoops_dump_oops ? KMSG_DUMP_OOPS > : KMSG_DUMP_PANIC; > else > pdata.max_reason = ramoops_max_reason; Oops, yes. ramoops_max_reason needs to also have an "unset" value so this can determine which was set... I'll get this fixed. Thanks for double-checking this! -- Kees Cook
