Since commit bdf8eafbf7f5 ("arm64: stacktrace: report source of unwind
data") a stack trace line can contain an additional info field that was not
present before, in the form of one or more letters in parentheses. E.g.:

  [  504.517915]  led_sysfs_enable+0x54/0x80 (P)
                                             ^^^

When this is present, decode_stacktrace decodes the line incorrectly:

  [  504.517915] led_sysfs_enable+0x54/0x80 P

Extend parsing to decode it correctly:

  [  504.517915] led_sysfs_enable (drivers/leds/led-core.c:455 (discriminator 7)) (P)

The regex to match such lines assumes the info can be extended in the
future to other uppercase characters, and will need to be extended in case
other characters will be used. Using a much more generic regex might incur
in false positives, so this looked like a good tradeoff.

Link: https://lkml.kernel.org/r/20241230-decode_stacktrace-fix-info-v1-1-984910659173@bootlin.com
Fixes: bdf8eafbf7f5 ("arm64: stacktrace: report source of unwind data")
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Miroslav Benes <mbenes@suse.cz>
Cc: Puranjay Mohan <puranjay@kernel.org>
Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

decode_stacktrace.sh adds a trailing space at the end of the decoded stack
if the module is not set (in most of the lines), which makes the some
lines of the stack having trailing space and some others not.

Do not add an extra space at the end of the line if module is not set,
adding consistency in output formatting.

Link: https://lkml.kernel.org/r/20241014100213.1873611-1-leitao@debian.org
Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Elliot Berman <quic_eberman@quicinc.com>
Reviewed-by: Carlos Llamas <cmllamas@google.com>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Cc: Bjorn Andersson <quic_bjorande@quicinc.com>
Cc: Luca Ceresoli <luca.ceresoli@bootlin.com>
Cc: Xiong Nandi <xndchn@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

When no parameters are passed, the usage instructions are presented only
when debuginfod-find is not found.  This makes sense because with
debuginfod none of the positional parameters are needed.  However it means
that users having debuginfod-find installed will have no chance of reading
the usage text without opening the file.

Many programs have a '-h' flag to get the usage, so add such a flag. 
Invoking 'scripts/decode_stacktrace.sh -h' will now show the usage text
and exit.

Link: https://lkml.kernel.org/r/20240823-decode_stacktrace-find_module-improvements-v2-3-d7a57d35558b@bootlin.com
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Cc: Alexis Lothoré (eBPF Foundation) <alexis.lothore@bootlin.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Sasha Levin <sashal@kernel.org>
Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

The syntax as expressed by usage() is not entirely correct: "<modules
path>" cannot be passed without "<base path>|auto".  Additionally human
reading of this syntax can be subject to misunderstanding due the mixture
of '|' and '[]'.

Improve readability in various ways:
 * rewrite using two lines for the two allowed usages
 * add square brackets around "<vmlinux>" as it is optional when using
   debuginfod-find
 * move "<modules path>" to inside the square brackets of the 2nd
   positional parameter
 * use underscores instead of spaces in <...> strings

Link: https://lkml.kernel.org/r/20240823-decode_stacktrace-find_module-improvements-v2-2-d7a57d35558b@bootlin.com
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Cc: Alexis Lothoré (eBPF Foundation) <alexis.lothore@bootlin.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Sasha Levin <sashal@kernel.org>
Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Patch series "scripts/decode_stacktrace.sh: improve error reporting and
usability", v2.

This small series improves usability of scripts/decode_stacktrace.sh by
improving the usage text and correctly reporting when modules are built
without debugging symbols.


This patch (of 3):

The find_module() function can fail for two reasons:

 * the module was not found
 * the module was found but without debugging info

In both cases the user is reported the same error:

   WARNING! Modules path isn't set, but is needed to parse this symbol

This is misleading in case the modules path is set correctly.

find_module() is currently implemented as a recursive function based on
global variables in order to check up to 4 different paths.  This is not
straightforward to read and even less to modify.

Besides, the debuginfo code at the beginning of find_module() is executed
identically every time the function is entered, i.e.  up to 4 times per
each module search due to recursion.

To be able to improve error reporting, first rewrite the find_module()
function to remove recursion.  The new version of the function iterates
over all the same (up to 4) paths as before and for each of them does the
same checks as before.  At the end of the iteration it is now able to
print an appropriate error message, so that has been moved from the caller
into find_module().

Finally, when the module is found but without debugging info, mention the
two Kconfig variables one needs to set in order to have the needed
debugging symbols.

Link: https://lkml.kernel.org/r/20240823-decode_stacktrace-find_module-improvements-v2-0-d7a57d35558b@bootlin.com
Link: https://lkml.kernel.org/r/20240823-decode_stacktrace-find_module-improvements-v2-1-d7a57d35558b@bootlin.com
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Cc: Alexis Lothoré (eBPF Foundation) <alexis.lothore@bootlin.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Luca Ceresoli <luca.ceresoli@bootlin.com>
Cc: Sasha Levin <sashal@kernel.org>
Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

nix only puts /usr/bin/env at the standard location (as required by
posix), so shebangs have to be tweaked.

Link: https://lkml.kernel.org/r/20240817215025.161628-1-kent.overstreet@linux.dev
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Bjorn Andersson <quic_bjorande@quicinc.com>
Cc: Elliot Berman <quic_eberman@quicinc.com>
Cc: Xiong Nandi <xndchn@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Sometimes there are special characters around module names in stack
traces, such as ARM32 with BACKTRACE_VERBOSE in "(%pS)" format, such as:
[<806e4845>] (dump_stack_lvl) from [<7f806013>] (hello_init+0x13/0x1000
[test])

In this case, $module will be "[test])", the trace can be decoded by
stripping the right parenthesis first: (dump_stack_lvl) from hello_init
(/foo/test.c:10) test.

Link: https://lkml.kernel.org/r/20240524042600.14738-3-xndchn@gmail.com
Signed-off-by: Xiong Nandi <xndchn@gmail.com>
Suggested-by: Elliot Berman <quic_eberman@quicinc.com>
Cc: Bjorn Andersson <quic_bjorande@quicinc.com>
Cc: Carlos Llamas <cmllamas@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Patch series "scripts/decode_stacktrace.sh: better support to ARM32".


This patch (of 2):

Since System.map is generated by cross-compile nm tool, we should use it here
too. Otherwise host nm may not recognize ARM Thumb-2 instruction address well.

Link: https://lkml.kernel.org/r/20240524042600.14738-1-xndchn@gmail.com
Link: https://lkml.kernel.org/r/20240524042600.14738-2-xndchn@gmail.com
Signed-off-by: Xiong Nandi <xndchn@gmail.com>
Reviewed-by: Elliot Berman <quic_eberman@quicinc.com>
Cc: Bjorn Andersson <quic_bjorande@quicinc.com>
Cc: Carlos Llamas <cmllamas@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

GNU's addr2line can have problems parsing a vmlinux built with LLVM,
particularly when LTO was used.  In order to decode the traces correctly
this patch adds the ability to switch to LLVM's utilities readelf and
addr2line.  The same approach is followed by Will in [1].

Before:
  $ scripts/decode_stacktrace.sh vmlinux < kernel.log
  [17716.240635] Call trace:
  [17716.240646] skb_cow_data (??:?)
  [17716.240654] esp6_input (ld-temp.o:?)
  [17716.240666] xfrm_input (ld-temp.o:?)
  [17716.240674] xfrm6_rcv (??:?)
  [...]

After:
  $ LLVM=1 scripts/decode_stacktrace.sh vmlinux < kernel.log
  [17716.240635] Call trace:
  [17716.240646] skb_cow_data (include/linux/skbuff.h:2172 net/core/skbuff.c:4503)
  [17716.240654] esp6_input (net/ipv6/esp6.c:977)
  [17716.240666] xfrm_input (net/xfrm/xfrm_input.c:659)
  [17716.240674] xfrm6_rcv (net/ipv6/xfrm6_input.c:172)
  [...]

Note that one could set CROSS_COMPILE=llvm- instead to hack around this
issue.  However, doing so can break the decodecode routine as it will
force the selection of other LLVM utilities down the line e.g.  llvm-as.

[1] https://lore.kernel.org/all/20230914131225.13415-3-will@kernel.org/

Link: https://lkml.kernel.org/r/20230929034836.403735-1-cmllamas@google.com
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Elliot Berman <quic_eberman@quicinc.com>
Tested-by: Justin Stitt <justinstitt@google.com>
Cc: Will Deacon <will@kernel.org>
Cc: John Stultz <jstultz@google.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Tom Rix <trix@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

When the kernel log is acquired over a serial cable it is not uncommon for
the log to contain carriage return characters, in addition to the expected
line feeds.

When this output is feed into decode_stacktrace.sh, handle_line() fails to
strip the trailing ']' off the module name, which results in find_module()
not being able to find the referred to kernel module.  This is reported to
the user as:

  WARNING! Modules path isn't set, but is needed to parse this symbol

The solution is to reconfigure the serial port, or to strip the carriage
returns from the log, but this isn't obvious from the error reported by
the script.

Instead, make decode_stacktrace.sh more user friendly by stripping the
trailing carriage return.

Link: https://lkml.kernel.org/r/20231225-decode-stacktrace-cr-v1-1-9f306f38cdde@quicinc.com
Signed-off-by: Bjorn Andersson <quic_bjorande@quicinc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>