Currently, the sud_test expects the emulated syscall to return the
emulated syscall number. This assumption only works on architectures
were the syscall calling convention use the same register for syscall
number/syscall return value. This is not the case for RISC-V and thus
the return value must be also emulated using the provided ucontext.

Signed-off-by: Clément Léger <[email protected]>
---
 tools/testing/selftests/syscall_user_dispatch/sud_test.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/tools/testing/selftests/syscall_user_dispatch/sud_test.c 
b/tools/testing/selftests/syscall_user_dispatch/sud_test.c
index b5d592d4099e..1b5553c19700 100644
--- a/tools/testing/selftests/syscall_user_dispatch/sud_test.c
+++ b/tools/testing/selftests/syscall_user_dispatch/sud_test.c
@@ -158,6 +158,14 @@ static void handle_sigsys(int sig, siginfo_t *info, void 
*ucontext)
 
        /* In preparation for sigreturn. */
        SYSCALL_DISPATCH_OFF(glob_sel);
+
+       /*
+        * Modify interrupted context returned value according to syscall
+        * calling convention
+        */
+#if defined(__riscv)
+       ((ucontext_t*)ucontext)->uc_mcontext.__gregs[REG_A0] = MAGIC_SYSCALL_1;
+#endif
 }
 
 TEST(dispatch_and_return)
-- 
2.40.1

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