arm: add initjmp()
Implement initjmp() for Arm. a non-standard extension to setjmp()/
longjmp() allowing to initialize a jump buffer with a function pointer
and a stack pointer. This will be useful to later introduce threads.
With this new function it becomes possible to longjmp() to a particular
function pointer (rather than to a point previously reached during
program execution as is the case with setjmp()), and with a custom stack.
Both things are needed to spin off a new thread. Then the usual
setjmp()/longjmp() pair is enough to save and restore a context, i.e.,
switch thread.
Signed-off-by: Jerome Forissier <jerome.forissier@linaro.org>
Acked-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
diff --git a/arch/arm/lib/setjmp_aarch64.S b/arch/arm/lib/setjmp_aarch64.S
index 1b8d000..01193cc 100644
--- a/arch/arm/lib/setjmp_aarch64.S
+++ b/arch/arm/lib/setjmp_aarch64.S
@@ -39,3 +39,13 @@
ret
ENDPROC(longjmp)
.popsection
+
+.pushsection .text.initjmp, "ax"
+ENTRY(initjmp)
+ /* x1: entry point address, x2: stack base, x3: stack size */
+ add x2, x2, x3
+ stp x1, x2, [x0,#88]
+ mov x0, #0
+ ret
+ENDPROC(initjmp)
+.popsection