linux/lib/Kconfig.kgdb

166 lines
5.6 KiB

kgdb: add kgdb internal test suite This patch adds regression tests for testing the kgdb core and arch specific implementation. The kgdb test suite is designed to be built into the kernel and not as a module because it uses a number of low level kernel and kgdb primitives which should not be exported externally. The kgdb test suite is designed as a KGDB I/O module which simulates the communications that a debugger would have with kgdb. The tests are broken up in to a line by line and referenced here as a "get" which is kgdb requesting input and "put" which is kgdb sending a response. The kgdb suite can be invoked from the kernel command line arguments system or executed dynamically at run time. The test suite uses the variable "kgdbts" to obtain the information about which tests to run and to configure the verbosity level. The following are the various characters you can use with the kgdbts= line: When using the "kgdbts=" you only choose one of the following core test types: A = Run all the core tests silently V1 = Run all the core tests with minimal output V2 = Run all the core tests in debug mode You can also specify optional tests: N## = Go to sleep with interrupts of for ## seconds to test the HW NMI watchdog F## = Break at do_fork for ## iterations S## = Break at sys_open for ## iterations NOTE: that the do_fork and sys_open tests are mutually exclusive. To invoke the kgdb test suite from boot you use a kernel start argument as follows: kgdbts=V1 kgdbwait Or if you wanted to perform the NMI test for 6 seconds and do_fork test for 100 forks, you could use: kgdbts=V1N6F100 kgdbwait The test suite can also be invoked at run time with: echo kgdbts=V1N6F100 > /sys/module/kgdbts/parameters/kgdbts Or as another example: echo kgdbts=V2 > /sys/module/kgdbts/parameters/kgdbts When developing a new kgdb arch specific implementation or using these tests for the purpose of regression testing, several invocations are required. 1) Boot with the test suite enabled by using the kernel arguments "kgdbts=V1F100 kgdbwait" ## If kgdb arch specific implementation has NMI use "kgdbts=V1N6F100 2) After the system boot run the basic test. echo kgdbts=V1 > /sys/module/kgdbts/parameters/kgdbts 3) Run the concurrency tests. It is best to use n+1 while loops where n is the number of cpus you have in your system. The example below uses only two loops. ## This tests break points on sys_open while [ 1 ] ; do find / > /dev/null 2>&1 ; done & while [ 1 ] ; do find / > /dev/null 2>&1 ; done & echo kgdbts=V1S10000 > /sys/module/kgdbts/parameters/kgdbts fg # and hit control-c fg # and hit control-c ## This tests break points on do_fork while [ 1 ] ; do date > /dev/null ; done & while [ 1 ] ; do date > /dev/null ; done & echo kgdbts=V1F1000 > /sys/module/kgdbts/parameters/kgdbts fg # and hit control-c Signed-off-by: Jason Wessel <jason.wessel@windriver.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-03-07 16:34:17 -06:00
kgdb: Delay "kgdbwait" to dbg_late_init() by default Using kgdb requires at least some level of architecture-level initialization. If nothing else, it relies on the architecture to pass breakpoints / crashes onto kgdb. On some architectures this all works super early, specifically it starts working at some point in time before Linux parses early_params's. On other architectures it doesn't. A survey of a few platforms: a) x86: Presumably it all works early since "ekgdboc" is documented to work here. b) arm64: Catching crashes works; with a simple patch breakpoints can also be made to work. c) arm: Nothing in kgdb works until paging_init() -> devicemaps_init() -> early_trap_init() Let's be conservative and, by default, process "kgdbwait" (which tells the kernel to drop into the debugger ASAP at boot) a bit later at dbg_late_init() time. If an architecture has tested it and wants to re-enable super early debugging, they can select the ARCH_HAS_EARLY_DEBUG KConfig option. We'll do this for x86 to start. It should be noted that dbg_late_init() is still called quite early in the system. Note that this patch doesn't affect when kgdb runs its init. If kgdb is set to initialize early it will still initialize when parsing early_param's. This patch _only_ inhibits the initial breakpoint from "kgdbwait". This means: * Without any extra patches arm64 platforms will at least catch crashes after kgdb inits. * arm platforms will catch crashes (and could handle a hardcoded kgdb_breakpoint()) any time after early_trap_init() runs, even before dbg_late_init(). Signed-off-by: Douglas Anderson <dianders@chromium.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Link: https://lore.kernel.org/r/20200507130644.v4.4.I3113aea1b08d8ce36dc3720209392ae8b815201b@changeid Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
2020-05-07 13:08:42 -07:00