From 24df4b958832cf7a42a82a205a536d8bcc02ab35 Mon Sep 17 00:00:00 2001 From: Wojtek Kosior Date: Tue, 17 Dec 2019 16:02:33 +0100 Subject: add forgotten libkernel.c --- libkernel.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) create mode 100644 libkernel.c (limited to 'libkernel.c') diff --git a/libkernel.c b/libkernel.c new file mode 100644 index 0000000..0955e0e --- /dev/null +++ b/libkernel.c @@ -0,0 +1,12 @@ +// This is the privileged code, that gets placed somewhere in +// unprivileged process' address space. It's compiled as relocatable, +// so it can be loaded at different address for different processes. + +void call_unprivileged(void (*address) (void)) { + // switch to PL0 + asm("cps #0b10000\n\r" + "isb" ::: "memory"); + + // jump to that unprivileged code + address(); +} -- cgit v1.2.3