[PATCH] riscv: tracing: Fix __write_overflow_field in ftrace_partial_regs()

[Charlie Jenkins]

The size of &regs->a0 is unknown, causing the error:

../include/linux/fortify-string.h:571:25: warning: call to
'__write_overflow_field' declared with attribute warning: detected write
beyond size of field (1st parameter); maybe use struct_group()?
[-Wattribute-warning]

Fix this by wrapping the required registers in pt_regs with
struct_group() and reference the group when doing the offending
memcpy().

Signed-off-by: Charlie Jenkins <charlie at rivosinc.com>
---
 arch/riscv/include/asm/ftrace.h |  2 +-
 arch/riscv/include/asm/ptrace.h | 18 ++++++++++--------
 2 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/arch/riscv/include/asm/ftrace.h b/arch/riscv/include/asm/ftrace.h
index c4721ce44ca474654b37b3d51bc0a63d46bc1eff..ec6db1162021fbf4fa48fc87e7984266040aa7d9 100644
--- a/arch/riscv/include/asm/ftrace.h
+++ b/arch/riscv/include/asm/ftrace.h
@@ -207,7 +207,7 @@ ftrace_partial_regs(const struct ftrace_regs *fregs, struct pt_regs *regs)
 {
 	struct __arch_ftrace_regs *afregs = arch_ftrace_regs(fregs);
 
-	memcpy(&regs->a0, afregs->args, sizeof(afregs->args));
+	memcpy(&regs->a_regs, afregs->args, sizeof(afregs->args));
 	regs->epc = afregs->epc;
 	regs->ra = afregs->ra;
 	regs->sp = afregs->sp;
diff --git a/arch/riscv/include/asm/ptrace.h b/arch/riscv/include/asm/ptrace.h
index b5b0adcc85c18e15c156de11172a5d7f03ada037..2910231977cb71dac3cc42f2dc32590284204057 100644
--- a/arch/riscv/include/asm/ptrace.h
+++ b/arch/riscv/include/asm/ptrace.h
@@ -23,14 +23,16 @@ struct pt_regs {
 	unsigned long t2;
 	unsigned long s0;
 	unsigned long s1;
-	unsigned long a0;
-	unsigned long a1;
-	unsigned long a2;
-	unsigned long a3;
-	unsigned long a4;
-	unsigned long a5;
-	unsigned long a6;
-	unsigned long a7;
+	struct_group(a_regs,
+		unsigned long a0;
+		unsigned long a1;
+		unsigned long a2;
+		unsigned long a3;
+		unsigned long a4;
+		unsigned long a5;
+		unsigned long a6;
+		unsigned long a7;
+	);
 	unsigned long s2;
 	unsigned long s3;
 	unsigned long s4;

---
base-commit: d082ecbc71e9e0bf49883ee4afd435a77a5101b6
change-id: 20250224-fix_ftrace_partial_regs-eddaf4a7e5ed
-- 
- Charlie