common-user/host/riscv: use tail pseudoinstruction for calling tail

The j pseudoinstruction maps to a JAL instruction, which can only handle
a jump to somewhere with a signed 20-bit destination. In case of static
linking and LTO'ing this easily leads to "relocation truncated to fit"
error.

Switch to use tail pseudoinstruction, which is the standard way to
tail-call a function in medium code model (emits AUIPC+JALR).

Signed-off-by: Icenowy Zheng <[email protected]>
Reviewed-by: Richard Henderson <[email protected]>
Message-ID: <[email protected]>
Signed-off-by: Alistair Francis <[email protected]>
Cc: [email protected]
(cherry picked from commit 22b448c)
Signed-off-by: Michael Tokarev <[email protected]>

Author: Icenowy

common-user/host/riscv/safe-syscall.inc.S

@@ -69,11 +69,11 @@ safe_syscall_end:
 
         /* code path setting errno */
 0:      neg     a0, a0
-        j       safe_syscall_set_errno_tail
+        tail    safe_syscall_set_errno_tail
 
         /* code path when we didn't execute the syscall */
 2:      li      a0, QEMU_ERESTARTSYS
-        j       safe_syscall_set_errno_tail
+        tail    safe_syscall_set_errno_tail
 
         .cfi_endproc
         .size   safe_syscall_base, .-safe_syscall_base