An issue has been found with current implementation of ARC signal restorer function in uClibc and how GDB handles it. When debugger information is not present, everything worked fine, because GDB would use a built-in logic to determine if function is a signal restorer. However when debugging information is present, debugger would rely solely on it and wouldn't use ARC-specific functions to detect signal handler frames. Because debug information for signal restorer is generated completely by the compiler, it lacks a marker, that identifies this as a signal frame that requires special handling. While it is possible to insert that marker via inline assembly, that still doesn't solve the whole problem, because some other expectations are not met by the debug information - there is no "nop" in front of the function, needed to fool debugger into thinking that this was a function call, and references to previous frame information need to be described manually. The simplest way to fix the problem is just to make sure that signal restorer function will not have any debug function at all, which can be done by writing it in assembly.
Alternative, more complex solution, where debug information for signal frame is manually defined can be found in glibc/sysdeps/unix/sysv/linux/x86_64/sigaction.c [1]. [1] https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/unix/sysv/linux/x86_64/sigaction.c;hb=HEAD Signed-off-by: Anton Kolesov <anton.kole...@synopsys.com> Anton
0001-arc-Ensure-that-debugger-can-recognize-sigrestorer.patch
Description: 0001-arc-Ensure-that-debugger-can-recognize-sigrestorer.patch
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