[binutils-gdb] Fix signals reported for faults on Solaris

[binutils-gdb] Fix signals reported for faults on Solaris

[Rainer Orth]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=7a28970742a8a1509917d409af14c84e1f666baa

commit 7a28970742a8a1509917d409af14c84e1f666baa
Author: Rainer Orth <ro@CeBiTec.Uni-Bielefeld.DE>
Date:   Thu Sep 12 10:40:59 2019 +0200

    Fix signals reported for faults on Solaris
    
    It's been a long-standing nuisance that gdb reported unaligned accesses
    on Solaris/SPARC as SIGSEGV, contrary to the shells and truss which
    correctly report SIGBUS instead.
    
    I could trace this down to the fault handling code in procfs.c
    (procfs_target::wait): when pr_why is set to PR_FAULTED, the current
    code sets the signal based on the fault number.  For one, the code gets
    this wrong for FLTACCESS (the unaligned access case) where it uses
    SIGSEGV.  What's worse, it's completely unnecessary to make up the
    signal number inside gdb.  Instead, it should just take what procfs
    reports to avoid mismatches, which is what this patch does.  I've
    completely removed the explicit handling of the various fault codes: for
    one, the list has already been incomplete, lacking FLTCPCOVF which
    existed since at least Solaris 8.  Besides, there's no reason to error
    out on unknown fault codes: either the fault causes a signal which can
    then be reported from procfs, or it doesn't (as for FLTPAGE) and no
    reporting is necessary.
    
    Tested on sparcv9-sun-solaris2.11 and x86_64-pc-solaris2.11.  Also
    spot-checked manually for a couple of cases (unaligned access, division
    by 0, NULL pointer dereference).
    
    	* procfs.c (procfs_target::wait) <PR_FAULTED>: Get signal from
    	prstatus.pr_lwp.pr_info instead of making it up.

Diff:
---
 gdb/ChangeLog |  5 +++++
 gdb/procfs.c  | 38 +++++---------------------------------
 2 files changed, 10 insertions(+), 33 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 4c35470..6d5f19d 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,8 @@
+2019-09-12  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>
+
+	* procfs.c (procfs_target::wait) <PR_FAULTED>: Get signal from
+	prstatus.pr_lwp.pr_info instead of making it up.
+
 2019-09-11  Christian Biesinger  <cbiesinger@google.com>
 
 	* auto-load.c (auto_load_expand_dir_vars): Update.
diff --git a/gdb/procfs.c b/gdb/procfs.c
index 5bc1c3b..848ac7d 100644
--- a/gdb/procfs.c
+++ b/gdb/procfs.c
@@ -2476,40 +2476,12 @@ wait_again:
 		wstat = (what << 8) | 0177;
 		break;
 	      case PR_FAULTED:
-		switch (what) {
-		case FLTWATCH:
-		  wstat = (SIGTRAP << 8) | 0177;
-		  break;
-		  /* FIXME: use si_signo where possible.  */
-		case FLTPRIV:
-		case FLTILL:
-		  wstat = (SIGILL << 8) | 0177;
-		  break;
-		case FLTBPT:
-		case FLTTRACE:
-		  wstat = (SIGTRAP << 8) | 0177;
-		  break;
-		case FLTSTACK:
-		case FLTACCESS:
-		case FLTBOUNDS:
-		  wstat = (SIGSEGV << 8) | 0177;
-		  break;
-		case FLTIOVF:
-		case FLTIZDIV:
-		case FLTFPE:
-		  wstat = (SIGFPE << 8) | 0177;
-		  break;
-		case FLTPAGE:	/* Recoverable page fault */
-		default:	/* FIXME: use si_signo if possible for
-				   fault.  */
-		  retval = ptid_t (-1);
-		  printf_filtered ("procfs:%d -- ", __LINE__);
-		  printf_filtered (_("child stopped for unknown reason:\n"));
-		  proc_prettyprint_why (why, what, 1);
-		  error (_("... giving up..."));
-		  break;
+		{
+		  int signo = pi->prstatus.pr_lwp.pr_info.si_signo;
+		  if (signo != 0)
+		    wstat = (signo << 8) | 0177;
 		}
-		break;	/* case PR_FAULTED: */
+		break;
 	      default:	/* switch (why) unmatched */
 		printf_filtered ("procfs:%d -- ", __LINE__);
 		printf_filtered (_("child stopped for unknown reason:\n"));