[PATCH 6.18 126/277] riscv: kgdb: fix several debug register assignment bugs

Greg Kroah-Hartman
2026-04-08T18:32:43Z

From: Paul Walmsley <pjw@kernel.org>

[ Upstream commit 834911eb8eef2501485d819b4eabebadc25c3497 ]

Fix several bugs in the RISC-V kgdb implementation:

- The element of dbg_reg_def[] that is supposed to pertain to the S1
register embeds instead the struct pt_regs offset of the A1
register. Fix this to use the S1 register offset in struct pt_regs.

- The sleeping_thread_to_gdb_regs() function copies the value of the
S10 register into the gdb_regs[] array element meant for the S9
register, and copies the value of the S11 register into the array
element meant for the S10 register. It also neglects to copy the
value of the S11 register. Fix all of these issues.

Fixes: fe89bd2be8667 ("riscv: Add KGDB support")
Cc: Vincent Chen <vincent.chen@sifive.com>
Link: https://patch.msgid.link/fde376f8-bcfd-bfe4-e467-07d8f7608d05@kernel.org
Signed-off-by: Paul Walmsley <pjw@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/riscv/kernel/kgdb.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/riscv/kernel/kgdb.c b/arch/riscv/kernel/kgdb.c
index 15fec5d1e6dec..0bf629204c76a 100644
--- a/arch/riscv/kernel/kgdb.c
+++ b/arch/riscv/kernel/kgdb.c
@@ -175,7 +175,7 @@ struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] = {
{DBG_REG_T1, GDB_SIZEOF_REG, offsetof(struct pt_regs, t1)},
{DBG_REG_T2, GDB_SIZEOF_REG, offsetof(struct pt_regs, t2)},
{DBG_REG_FP, GDB_SIZEOF_REG, offsetof(struct pt_regs, s0)},
- {DBG_REG_S1, GDB_SIZEOF_REG, offsetof(struct pt_regs, a1)},
+ {DBG_REG_S1, GDB_SIZEOF_REG, offsetof(struct pt_regs, s1)},
{DBG_REG_A0, GDB_SIZEOF_REG, offsetof(struct pt_regs, a0)},
{DBG_REG_A1, GDB_SIZEOF_REG, offsetof(struct pt_regs, a1)},
{DBG_REG_A2, GDB_SIZEOF_REG, offsetof(struct pt_regs, a2)},
@@ -244,8 +244,9 @@ sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *task)
gdb_regs[DBG_REG_S6_OFF] = task->thread.s[6];
gdb_regs[DBG_REG_S7_OFF] = task->thread.s[7];
gdb_regs[DBG_REG_S8_OFF] = task->thread.s[8];
- gdb_regs[DBG_REG_S9_OFF] = task->thread.s[10];
- gdb_regs[DBG_REG_S10_OFF] = task->thread.s[11];
+ gdb_regs[DBG_REG_S9_OFF] = task->thread.s[9];
+ gdb_regs[DBG_REG_S10_OFF] = task->thread.s[10];
+ gdb_regs[DBG_REG_S11_OFF] = task->thread.s[11];
gdb_regs[DBG_REG_EPC_OFF] = task->thread.ra;
}

--
2.53.0