talos-skiboot/core/stack.c, branch master

core/opal: Emergency stack for re-entry

2018-04-19T01:23:07+00:00

This detects OPAL being re-entered by the OS, and switches to an emergency stack if it was. This protects the firmware's main stack from re-entrancy and allows the OS to use NMI facilities for crash / debug functionality. Further nested re-entry will destroy the previous emergency stack and prevent returning, but those should be rare cases. This stack is sized at 16kB, which doubles the size of CPU stacks, so as not to introduce a regression in primary stack size. The 16kB stack originally had a 4kB machine check stack at the top, which was removed by 80eee1946 ("opal: Remove machine check interrupt patching in OPAL."). So it is possible the size could be tightened again, but that would require further analysis. Signed-off-by: Nicholas Piggin Signed-off-by: Stewart Smith

core/stack: backtrace unwind basic OPAL call details

2018-04-19T01:23:07+00:00

Put OPAL callers' r1 into the stack back chain, and then use that to unwind back to the OPAL entry frame (as opposed to boot entry, which has a 0 back chain). >From there, dump the OPAL call token and the caller's r1. A backtrace looks like this: CPU 0000 Backtrace: S: 0000000031c03ba0 R: 000000003001a548 ._abort+0x4c S: 0000000031c03c20 R: 000000003001baac .opal_run_pollers+0x3c S: 0000000031c03ca0 R: 000000003001bcbc .opal_poll_events+0xc4 S: 0000000031c03d20 R: 00000000300051dc opal_entry+0x12c --- OPAL call entry token: 0xa caller R1: 0xc0000000006d3b90 --- This is pretty basic for the moment, but it does give you the bottom of the Linux stack. It will allow some interesting improvements in future. First, with the eframe, all the call's parameters can be printed out as well. The ___backtrace / ___print_backtrace API needs to be reworked in order to support this, but it's otherwise very simple (see opal_trace_entry()). Second, it will allow Linux's stack to be passed back to Linux via a debugging opal call. This will allow Linux's BUG() or xmon to also print the Linux back trace in case of a NMI or MCE or watchdog lockup that hits in OPAL. Signed-off-by: Nicholas Piggin Signed-off-by: Stewart Smith

core/utils: add snprintf_symbol

2018-02-09T00:21:42+00:00

get_symbol is difficult to use. Add snprintf_symbol helper which prints a symbol into a buffer with length, and returns the number of bytes used, similarly to snprintf. Use this in the stack dumping code rather than open-coding it. Signed-off-by: Nicholas Piggin Signed-off-by: Stewart Smith

lock: Add additional lock auditing code

2017-12-21T04:15:36+00:00

Keep track of lock owner name and replace lock_depth counter with a per-cpu list of locks held by the cpu. This allows us to print the actual locks held in case we hit the (in)famous message about opal_pollers being run with a lock held. It also allows us to warn (and drop them) if locks are still held when returning to the OS or completing a scheduled job. Signed-off-by: Benjamin Herrenschmidt Reviewed-by: Nicholas Piggin [stewart: fix unit tests] Signed-off-by: Stewart Smith

core/backtrace: Serialise printing backtraces

2017-07-25T05:05:07+00:00

Add a lock so that only one thread can print a backtrace at a time. This should prevent multiple threads from garbaling each other's backtraces. Signed-off-by: Oliver O'Halloran Signed-off-by: Stewart Smith

stack: Don't recurse into __stack_chk_fail

2016-12-22T02:17:28+00:00

Signed-off-by: Benjamin Herrenschmidt Signed-off-by: Stewart Smith

core: Fix backtrace for gcc 6

2016-03-30T07:15:39+00:00

GCC 6 warns when we look at any stack frame other than our own, ie any argument to __builtin_frame_address other than zero. Signed-off-by: Joel Stanley Signed-off-by: Stewart Smith

Fix early backtraces

2016-03-04T05:06:51+00:00

If we fail an assert() before we add a mem region, such as missing chip-id in a dt xscom node, we don't get a backtrace: [836883,0] Assert fail: core/device.c:870:id != 0xffffffff [848859,0] Aborting! CPU 0000 Backtrace: This patch adjusts the top_of_ram value compared to the fp stack frame to assume one stack early on so we get a backtrace: [440546,0] Assert fail: core/device.c:822:id != 0xffffffff [452522,0] Aborting! CPU 0000 Backtrace: S: 0000000031c03b70 R: 00000000300135d0 .backtrace+0x24 S: 0000000031c03bf0 R: 0000000030017f38 ._abort+0x4c S: 0000000031c03c70 R: 0000000030017fb4 .assert_fail+0x34 S: 0000000031c03cf0 R: 0000000030021830 .dt_get_chip_id+0x24 S: 0000000031c03d60 R: 00000000300143cc .init_chips+0x23c S: 0000000031c03e30 R: 0000000030013ab8 .main_cpu_entry+0x110 S: 0000000031c03f00 R: 000000003000254c boot_entry+0x19c Signed-off-by: Ryan Grimm Signed-off-by: Stewart Smith

Don't try to print symbol when we didn't find one

2015-08-11T06:33:32+00:00

Signed-off-by: Stewart Smith

Add symbolic backtraces and expose skiboot map to Linux

2014-11-18T08:33:51+00:00

We use a double link technique, doing a first pass with a .o containing a dummy symbol map, then re-linking with a new .o Signed-off-by: Benjamin Herrenschmidt