Messages in this thread | | | Date | Thu, 17 Jun 2021 14:36:56 +0200 | From | Jessica Yu <> | Subject | Re: [PATCH v7 0/5] printk: Userspace format indexing support |
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+++ Petr Mladek [17/06/21 12:10 +0200]: >On Tue 2021-06-15 17:52:20, Chris Down wrote: >> We have a number of systems industry-wide that have a subset of their >> functionality that works as follows: >> >> 1. Receive a message from local kmsg, serial console, or netconsole; >> 2. Apply a set of rules to classify the message; >> 3. Do something based on this classification (like scheduling a >> remediation for the machine), rinse, and repeat. >> >> This provides a solution to the issue of silently changed or deleted >> printks: we record pointers to all printk format strings known at >> compile time into a new .printk_index section, both in vmlinux and >> modules. At runtime, this can then be iterated by looking at >> <debugfs>/printk/index/<module>, which emits the following format, both >> readable by humans and able to be parsed by machines: >> >> $ head -1 vmlinux; shuf -n 5 vmlinux >> # <level[,flags]> filename:line function "format" >> <5> block/blk-settings.c:661 disk_stack_limits "%s: Warning: Device %s is misaligned\n" >> <4> kernel/trace/trace.c:8296 trace_create_file "Could not create tracefs '%s' entry\n" >> <6> arch/x86/kernel/hpet.c:144 _hpet_print_config "hpet: %s(%d):\n" >> <6> init/do_mounts.c:605 prepare_namespace "Waiting for root device %s...\n" >> <6> drivers/acpi/osl.c:1410 acpi_no_auto_serialize_setup "ACPI: auto-serialization disabled\n" >> >> This mitigates the majority of cases where we have a highly-specific >> printk which we want to match on, as we can now enumerate and check >> whether the format changed or the printk callsite disappeared entirely >> in userspace. This allows us to catch changes to printks we monitor >> earlier and decide what to do about it before it becomes problematic. >> >> There is no additional runtime cost for printk callers or printk itself, >> and the assembly generated is exactly the same. >> >> Chris Down (5): >> string_helpers: Escape double quotes in escape_special >> printk: Straighten out log_flags into printk_info_flags >> printk: Rework parse_prefix into printk_parse_prefix >> printk: Userspace format indexing support >> printk: index: Add indexing support to dev_printk > >The patchset looks ready for linux-next from my POV. I could fixup the >messages as suggested by Andy when pushing. > >Well, I would still like to get acks from: > > + Andy for the 1st patch > + Jessica for the changes in the module loader code in 4th patch.
Hi Petr, the module.{c,h} changes are fine by me:
Acked-by: Jessica Yu <jeyu@kernel.org>
Thank you,
Jessica
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