https://bugs.kde.org/show_bug.cgi?id=273489
Andreas Arnez <ar...@linux.ibm.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|REPORTED |RESOLVED
CC| |ar...@linux.ibm.com
Resolution|--- |FIXED
--- Comment #4 from Andreas Arnez <ar...@linux.ibm.com> ---
(In reply to Christian Borntraeger from comment #1)
> We will need to issue SIGSEGV/SIGBUS from some instructions (e.g. crypto for
> wrong function codes will cause a specification exception that causes Linux
> to deliver a SIGSEGV).
That's not quite correct. Instead, specification exceptions lead to SIGILL.
For a full overview of how architectural exceptions are translated to Linux
signals, see the section "Exception Interface" in the s390x ABI:
https://github.com/ibm/s390x-abi
In the meantime we added lots of checks in the translator, to yield SIGILL via
Ijk_NoDecode in cases where the hardware would generate specification
exceptions. See, e.g. the many invocations of s390_insn_assert() in
guest_s390_toIR.c.
Similarly, the extension handlers in extension-s390x.c yield SIGILL by
returning ExtErr_Illop when they recognize inputs that would generate a
specification exception.
These two mechanisms cover almost all relevant cases where we like to
synthesize signals for bad instructions. A few special cases might be missing,
particularly those that require run-time checks such as for the "load and add"
operand alignment. If the need arises, those should be addressed with separate
Bugs.
SIGSEGV/SIGBUS, on the other hand, are generated for translation exceptions
only. This should not be specific to s390x.
With this, I consider this Bug "fixed".
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