[RFC PATCH V3 13/43] rv64ilp32_abi: riscv: Correct stackframe layout

[guoren]

From: "Guo Ren (Alibaba DAMO Academy)" <guoren@xxxxxxxxxx>

In RV64ILP32 ABI, the callee saved fp & ra are 64-bit width,
not long size. This patch corrects the layout for the struct
stackframe.

echo c > /proc/sysrq-trigger

Before the patch:

sysrq: Trigger a crash
Kernel panic - not syncing: sysrq triggered crash
CPU: 0 PID: 102 Comm: sh Not tainted ...
Hardware name: riscv-virtio,qemu (DT)
Call Trace:
---[ end Kernel panic - not syncing: sysrq triggered crash ]---

After the patch:

sysrq: Trigger a crash
Kernel panic - not syncing: sysrq triggered crash
CPU: 0 PID: 102 Comm: sh Not tainted ...
Hardware name: riscv-virtio,qemu (DT)
Call Trace:
[<c00050c8>] dump_backtrace+0x1e/0x26
[<c086dcae>] show_stack+0x2e/0x3c
[<c0878e00>] dump_stack_lvl+0x40/0x5a
[<c0878e30>] dump_stack+0x16/0x1e
[<c086df7c>] panic+0x10c/0x2a8
[<c04f4c1e>] sysrq_reset_seq_param_set+0x0/0x76
[<c04f52cc>] __handle_sysrq+0x9c/0x19c
[<c04f5946>] write_sysrq_trigger+0x64/0x78
[<c020c7f6>] proc_reg_write+0x4a/0xa2
[<c01acf0a>] vfs_write+0xac/0x308
[<c01ad2b8>] ksys_write+0x62/0xda
[<c01ad33e>] sys_write+0xe/0x16
[<c0879860>] do_trap_ecall_u+0xd8/0xda
[<c00037de>] ret_from_exception+0x0/0x66
---[ end Kernel panic - not syncing: sysrq triggered crash ]---

Signed-off-by: Guo Ren (Alibaba DAMO Academy) <guoren@xxxxxxxxxx>
---
 arch/riscv/include/asm/stacktrace.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/riscv/include/asm/stacktrace.h b/arch/riscv/include/asm/stacktrace.h
index b1495a7e06ce..556655cab09d 100644
--- a/arch/riscv/include/asm/stacktrace.h
+++ b/arch/riscv/include/asm/stacktrace.h
@@ -8,7 +8,13 @@
 
 struct stackframe {
 	unsigned long fp;
+#if IS_ENABLED(CONFIG_64BIT) && (BITS_PER_LONG == 32)
+	unsigned long __fp;
+#endif
 	unsigned long ra;
+#if IS_ENABLED(CONFIG_64BIT) && (BITS_PER_LONG == 32)
+	unsigned long __ra;
+#endif
 };
 
 extern void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
-- 
2.40.1