ftrace creates entries for each syscall in the tracefs but has failed
since commit 08d0ce30e0e4 ("riscv: Implement syscall wrappers") which
prefixes all riscv syscalls with __riscv_.

So fix this by implementing arch_syscall_match_sym_name() which allows us
to ignore this prefix.

And also ignore compat syscalls like x86/arm64 by implementing
arch_trace_is_compat_syscall().

Fixes: 08d0ce30e0e4 ("riscv: Implement syscall wrappers")
Signed-off-by: Alexandre Ghiti <redacted>
---
 arch/riscv/include/asm/ftrace.h | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/arch/riscv/include/asm/ftrace.h b/arch/riscv/include/asm/ftrace.h
index 740a979171e5..2b2f5df7ef2c 100644
--- a/arch/riscv/include/asm/ftrace.h
+++ b/arch/riscv/include/asm/ftrace.h

@@ -31,6 +31,27 @@ static inline unsigned long ftrace_call_adjust(unsigned long addr)
        return addr;
 }

+/*
+ * Let's do like x86/arm64 and ignore the compat syscalls.
+ */
+#define ARCH_TRACE_IGNORE_COMPAT_SYSCALLS
+static inline bool arch_trace_is_compat_syscall(struct pt_regs *regs)
+{
+       return is_compat_task();
+}
+
+#define ARCH_HAS_SYSCALL_MATCH_SYM_NAME
+static inline bool arch_syscall_match_sym_name(const char *sym,
+                                              const char *name)
+{
+       /*
+        * Since all syscall functions have __riscv_ prefix, we must skip it.
+        * However, as we described above, we decided to ignore compat
+        * syscalls, so we don't care about __riscv_compat_ prefix here.
+        */
+       return !strcmp(sym + 8, name);
+}