From: Andreas Arnez Date: Fri, 13 Jul 2018 10:46:14 +0000 (+0200) Subject: S390: Fix displaced stepping of "basr r,0" X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=5c1eda30f55e9c543de26fec0246f4d7655c81e4;p=binutils-gdb.git S390: Fix displaced stepping of "basr r,0" The BASR instruction behaves differently depending on whether the second operand is a number from 1 to 15, or zero. In the former case BASR jumps to the address contained in the general register of that number, but in the latter case no jump is performed. GDB's displaced-stepping logic does not distinguish these cases, although it should. This is fixed. In the case where no jump is performed the PC is adjusted to point back after the original instruction. Otherwise the PC is left alone. gdb/ChangeLog: * s390-tdep.c (s390_displaced_step_fixup): Adjust PC for a non-branching basr. --- diff --git a/gdb/ChangeLog b/gdb/ChangeLog index cc61dab5861..7b808eb3a76 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,8 @@ +2018-07-13 Andreas Arnez + + * s390-tdep.c (s390_displaced_step_fixup): Adjust PC for a + non-branching basr. + 2018-07-12 Philippe Waroquiers * Makefile.in (SUBDIR_UNITTESTS_SRCS): Add diff --git a/gdb/s390-tdep.c b/gdb/s390-tdep.c index 77e64af5839..e962824ca04 100644 --- a/gdb/s390-tdep.c +++ b/gdb/s390-tdep.c @@ -492,6 +492,9 @@ s390_displaced_step_fixup (struct gdbarch *gdbarch, /* Recompute saved return address in R1. */ regcache_cooked_write_unsigned (regs, S390_R0_REGNUM + r1, amode | (from + insnlen)); + /* Update PC iff the instruction doesn't actually branch. */ + if (insn[0] == op_basr && r2 == 0) + regcache_write_pc (regs, from + insnlen); } /* Handle absolute branch instructions. */