From 10c19fadfd45da5262d2f8b9624be71c274ff15d Mon Sep 17 00:00:00 2001 From: Shahab Vahedi Date: Thu, 12 Nov 2020 12:50:33 +0100 Subject: [PATCH] arc: Write correct "eret" value during register collection In collect_register() function of arc-linux-tdep.c, the "eret" (exception return) register value was not being reported correctly. This patch fixes that. Background: When asked for the "pc" value, we have to update the "eret" register with GDB's STOP_PC. The "eret" instructs the kernel code where to jump back when an instruction has stopped due to a breakpoint. This is how collect_register() was doing so: --------------8<-------------- if (regnum == gdbarch_pc_regnum (gdbarch)) regnum = ARC_ERET_REGNUM; regcache->raw_collect (regnum, buf + arc_linux_core_reg_offsets[regnum]); -------------->8-------------- Root cause: Although this is using the correct offset (ERET register's), it is also changing the REGNUM itself. Therefore, raw_collect (regnum, ...) is not reading from "pc" anymore. v2: - Fix a copy/paste issue as rightfully addressed by Tom [1]. [1] https://sourceware.org/pipermail/gdb-patches/2020-November/173208.html gdb/ChangeLog: * arc-linux-tdep.c (collect_register): Populate "eret" by "pc" value from the regcache when asked for "pc" value. --- gdb/ChangeLog | 5 +++++ gdb/arc-linux-tdep.c | 10 +++++++--- 2 files changed, 12 insertions(+), 3 deletions(-) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 038d45f4ec4..4d1f5241e8c 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,8 @@ +2020-11-12 Shahab Vahedi + + * arc-linux-tdep.c (collect_register): Populate "eret" by + "pc" value from the regcache when asked for "pc" value. + 2020-11-12 Tom Tromey PR rust/26799: diff --git a/gdb/arc-linux-tdep.c b/gdb/arc-linux-tdep.c index 9ff5f1214a1..6e74bae8056 100644 --- a/gdb/arc-linux-tdep.c +++ b/gdb/arc-linux-tdep.c @@ -319,8 +319,10 @@ static void collect_register (const struct regcache *regcache, struct gdbarch *gdbarch, int regnum, gdb_byte *buf) { + int offset; + /* Skip non-existing registers. */ - if ((arc_linux_core_reg_offsets[regnum] == ARC_OFFSET_NO_REGISTER)) + if (arc_linux_core_reg_offsets[regnum] == ARC_OFFSET_NO_REGISTER) return; /* The address where the execution has stopped is in pseudo-register @@ -332,8 +334,10 @@ collect_register (const struct regcache *regcache, struct gdbarch *gdbarch, the program will continue at the address after the current instruction. */ if (regnum == gdbarch_pc_regnum (gdbarch)) - regnum = ARC_ERET_REGNUM; - regcache->raw_collect (regnum, buf + arc_linux_core_reg_offsets[regnum]); + offset = arc_linux_core_reg_offsets[ARC_ERET_REGNUM]; + else + offset = arc_linux_core_reg_offsets[regnum]; + regcache->raw_collect (regnum, buf + offset); } void -- 2.30.2