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pstore/ram: Introduce max_reason and convert dump_oops

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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.

Co-developed-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Link: https://lore.kernel.org/lkml/20200515184434.8470-6-keescook@chromium.org/
Signed-off-by: Kees Cook <keescook@chromium.org>
Change-Id: I827694ae9911af469f9d2053b3cd9a3b5f6ef5cb
This commit is contained in:
Kees Cook 2020-05-13 14:35:03 -07:00 committed by Davide Garberi
parent 60cd494f4a
commit d93e93a719
4 changed files with 51 additions and 25 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
Documentation/admin-guide/ramoops.rst
View File

@ -34,11 +34,17 @@ memory are implementation defined, and won't work on many ARMs such as omaps. Se
full cache on it. This can improve the performance.
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).
@ -92,7 +98,7 @@ Setting the ramoops parameters can be done in several different manners:
.mem_address = <...>,
.mem_type = <...>,
.record_size = <...>,
.dump_oops = <...>,
.max_reason = <...>,
.ecc = <...>,
};

2
drivers/platform/chrome/chromeos_pstore.c
View File

@ -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 = {

58
fs/pstore/ram.c
View File

@ -58,10 +58,10 @@ 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);
MODULE_PARM_DESC(dump_oops,
"set to 1 to dump oopses, 0 to only dump panics (default 1)");
static int ramoops_max_reason = -1;
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);
@ -70,6 +70,11 @@ MODULE_PARM_DESC(ramoops_ecc,
"ECC buffer size in bytes (1 is a special value, means 16 "
"bytes ECC)");
static int ramoops_dump_oops = -1;
module_param_named(dump_oops, ramoops_dump_oops, int, 0600);
MODULE_PARM_DESC(dump_oops,
"(deprecated: use max_reason instead) set to 1 to dump oopses & panics, 0 to only dump panics");
struct ramoops_context {
struct persistent_ram_zone **dprzs; /* Oops dump zones */
struct persistent_ram_zone *cprz; /* Console zone */
@ -82,7 +87,6 @@ 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;
@ -431,16 +435,14 @@ 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.
@ -737,7 +739,14 @@ static int ramoops_parse_dt(struct platform_device *pdev,
pdata->mem_address = res->start;
if (of_property_read_u32(of_node, "mem-type", &pdata->mem_type))
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) { \
ret = ramoops_parse_dt_size(pdev, name, &value); \
@ -752,6 +761,7 @@ static int ramoops_parse_dt(struct platform_device *pdev,
parse_size("pmsg-size", pdata->pmsg_size);
parse_size("ecc-size", pdata->ecc_info.ecc_size);
parse_size("flags", pdata->flags);
parse_size("max-reason", pdata->max_reason);
#undef parse_size
@ -837,7 +847,6 @@ 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;
@ -880,8 +889,10 @@ 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)
@ -917,7 +928,7 @@ 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;
@ -1002,7 +1013,16 @@ 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;
/* If "max_reason" is set, its value has priority over "dump_oops". */
if (ramoops_max_reason >= 0)
pdata.max_reason = ramoops_max_reason;
/* Otherwise, if "dump_oops" is set, parse it into "max_reason". */
else if (ramoops_dump_oops != -1)
pdata.max_reason = ramoops_dump_oops ? KMSG_DUMP_OOPS
: KMSG_DUMP_PANIC;
/* And if neither are explicitly set, use the default. */
else
pdata.max_reason = KMSG_DUMP_OOPS;
pdata.flags = RAMOOPS_FLAG_FTRACE_PER_CPU;
/*

2
include/linux/pstore_ram.h
View File

@ -133,7 +133,7 @@ struct ramoops_platform_data {
unsigned long console_size;
unsigned long ftrace_size;
unsigned long pmsg_size;
int dump_oops;
int max_reason;
u32 flags;
struct persistent_ram_ecc_info ecc_info;
};