On Wed, 06 Dec 2023 05:44:37 PST (-0800), cleger@rivosinc.com wrote:
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 cleger@rivosinc.com Reviewed-by: Palmer Dabbelt palmer@rivosinc.com Acked-by: Palmer Dabbelt palmer@rivosinc.com
Changes in V2:
- Changes comment to be more explicit
- Use A7 syscall arg rather than hardcoding MAGIC_SYSCALL_1
.../selftests/syscall_user_dispatch/sud_test.c | 14 ++++++++++++++ 1 file changed, 14 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..d975a6767329 100644 --- a/tools/testing/selftests/syscall_user_dispatch/sud_test.c +++ b/tools/testing/selftests/syscall_user_dispatch/sud_test.c @@ -158,6 +158,20 @@ static void handle_sigsys(int sig, siginfo_t *info, void *ucontext)
/* In preparation for sigreturn. */ SYSCALL_DISPATCH_OFF(glob_sel);
- /*
* The tests for argument handling assume that `syscall(x) == x`. This* is a NOP on x86 because the syscall number is passed in %rax, which* happens to also be the function ABI return register. Other* architectures may need to swizzle the arguments around.*/+#if defined(__riscv) +/* REG_A7 is not defined in libc headers */ +# define REG_A7 (REG_A0 + 7)
- ((ucontext_t *)ucontext)->uc_mcontext.__gregs[REG_A0] =
((ucontext_t *)ucontext)->uc_mcontext.__gregs[REG_A7];+#endif }
TEST(dispatch_and_return)
Thanks.
Thomas: looks like you picked up all the commits that touched this? No rush on my end, just LMK if you want me to pick it up -- I'm going to leave it alone for now.