This patch fixes a problem on nios2-linux-gnu with stepping past the
kernel helper __kuser_cmpxchg, which was exposed by the testcase
gdb.threads/watchpoint-fork.exp. The kernel maps this function into
user space on an unwritable page. In this testcase, the cmpxchg
helper is invoked indirectly from the setbuf call in the test program.
Since this target lacks hardware breakpoint/watchpoint support, GDB
tries to single-step through the program by setting software
breakpoints, and was just giving an error when it reached the function
on the unwritable page.
The solution here is to always step over the call instead of stepping
into it; cmpxchg is supposed to be an atomic operation so this
behavior seems reasonable. The hook in nios2_get_next_pc is somewhat
generic, but at present cmpxchg is the only helper provided by the
Linux kernel that is invoked by an ordinary function call. (Signal
return trampolines also go through the unwritable page but not by a
function call.)
Fixing this issue also revealed that the testcase needs a much larger
timeout factor when software single-stepping is used. That has also
been fixed in this patch.
gdb/ChangeLog
2019-03-28 Sandra Loosemore <sandra@codesourcery.com>
* nios2-tdep.h (struct gdbarch_tdep): Add is_kernel_helper.
* nios2-tdep.c (nios2_get_next_pc): Skip over kernel helpers.
* nios2-linux-tdep.c (nios2_linux_is_kernel_helper): New.
(nios2_linux_init_abi): Install it.
gdb/testsuite/ChangeLog
2019-03-28 Sandra Loosemore <sandra@codesourcery.com>
* gdb.threads/watchpoint-fork.exp (test): Use large timeout
factor when no hardware watchpoint support.
This commit applies all changes made after running the gdb/copyright.py
script.
Note that one file was flagged by the script, due to an invalid
copyright header
(gdb/unittests/basic_string_view/element_access/char/empty.cc).
As the file was copied from GCC's libstdc++-v3 testsuite, this commit
leaves this file untouched for the time being; a patch to fix the header
was sent to gcc-patches first.
gdb/ChangeLog:
Update copyright year range in all GDB files.
This applies the second part of GDB's End of Year Procedure, which
updates the copyright year range in all of GDB's files.
gdb/ChangeLog:
Update copyright year range in all GDB files.
Andrew Jenner <andrew@codesourcery.com>
Chung-Lin Tang <cltang@codesourcery.com>
Julian Brown <julian@codesourcery.com>
Based on the nios2-elf port from Altera Corporation.
gdb/
* Makefile.in (ALL_TARGET_OBS): Add nios2-tdep.o and
nios2-linux-tdep.o.
(HFILES_NO_SRCDIR): Add nios2-tdep.h.
(ALLDEPFILES): Add nios2-tdep.c and nios2-linux-tdep.c.
* configure.tgt: Add nios2*-*-linux* and nios2*-*-* targets.
* nios2-tdep.h: New.
* nios2-tdep.c: New.
* nios2-linux-tdep.c: New.
* features/Makefile (WHICH): Add nios2-linux.
(nios2-linux-expedite): Set.
* features/nios2-cpu.xml: New.
* features/nios2.xml: New.
* features/nios2-linux.xml: New.
* features/nios2.c: New (autogenerated).
* features/nios2-linux.c: New (autogenerated).
* regformats/nios2-linux.dat: New (autogenerated).
* NEWS (Changes since GDB 7.6): Add new Nios II targets
and commands.
gdb/doc/
* gdb.texinfo (Nios II): New section.
(Nios II Features): New section.
Sandra Loosemore
Joel Brobecker