make sh clone asm fdpic-compatible

clone calls back to a function pointer provided by the caller, which
will actually be a pointer to a function descriptor on fdpic. the
obvious solution is to have a separate version of clone for fdpic, but
I have taken a simpler approach to go around the problem. instead of
calling the pointed-to function from asm, a direct call is made to an
internal C function which then calls the pointed-to function. this
lets the C compiler generate the appropriate calling convention for an
indirect call with no need for ABI-specific assembly.

diff --git a/arch/sh/src/__shcall.c b/arch/sh/src/__shcall.c
new file mode 100644 (file)
index 0000000..dfe80a7
--- /dev/null
+++ b/arch/sh/src/__shcall.c
@@ -0,0 +1,5 @@
+__attribute__((__visibility__("hidden")))
+int __shcall(void *arg, int (*func)(void *))
+{
+       return func(arg);
+}

diff --git a/src/thread/sh/clone.s b/src/thread/sh/clone.s
index f8ad845..aa4d0df 100644 (file)
--- a/src/thread/sh/clone.s
+++ b/src/thread/sh/clone.s
@@ -33,10 +33,12 @@ __clone:
         nop
 
 1:     ! we are the child, call fn(arg)
-       jsr    @r1
-        mov   r2, r4
+       mov.l  1f, r0
+       mov    r1, r5
+       bsrf   r0
+        mov    r2, r4
 
-       mov   #1, r3   ! __NR_exit
+2:     mov   #1, r3   ! __NR_exit
        mov   r0, r4
        trapa #31
 
@@ -45,3 +47,7 @@ __clone:
        or   r0, r0
        or   r0, r0
        or   r0, r0
+
+.align 2
+.hidden __shcall
+1:     .long __shcall@PCREL+(.-2b)