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From: Bernd Edlinger <bernd.edlinger@hotmail.de>
To: "gdb-patches@sourceware.org" <gdb-patches@sourceware.org>
Subject: [PATCH] sim: riscv: Fix PC at gdb breakpoints
Date: Fri, 12 Apr 2024 09:31:17 +0200	[thread overview]
Message-ID: <AS8P193MB12851EAC96A002B34CB57EBBE4042@AS8P193MB1285.EURP193.PROD.OUTLOOK.COM> (raw)

The uncompressed EBREAK instruction does not work
correctly this way, and the comment saying that
GDB expects us to step over EBREAK is just wrong.
The PC was always 4 bytes too high, which skips one
instruction at break and step over commands, and
causes complete chaos.  The compressed EBREAK was
already implemented correctly.

Tested by using gdb's "target sim" and single-stepping.
---
 sim/riscv/sim-main.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/sim/riscv/sim-main.c b/sim/riscv/sim-main.c
index 0876d455570..66b99e40314 100644
--- a/sim/riscv/sim-main.c
+++ b/sim/riscv/sim-main.c
@@ -624,9 +624,7 @@ execute_i (SIM_CPU *cpu, unsigned_word iw, const struct riscv_opcode *op)
       break;
     case MATCH_EBREAK:
       TRACE_INSN (cpu, "ebreak;");
-      /* GDB expects us to step over EBREAK.  */
-      sim_engine_halt (sd, cpu, NULL, riscv_cpu->pc + 4, sim_stopped,
-		       SIM_SIGTRAP);
+      sim_engine_halt (sd, cpu, NULL, riscv_cpu->pc, sim_stopped, SIM_SIGTRAP);
       break;
     case MATCH_ECALL:
       TRACE_INSN (cpu, "ecall;");
-- 
2.25.1


             reply	other threads:[~2024-04-12  7:29 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-04-12  7:31 Bernd Edlinger [this message]
2024-04-12  9:44 ` Andrew Burgess
2024-04-15  8:21   ` Bernd Edlinger

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