u-boot/arch/arm/lib/setjmp_aarch64.S
Philipp Tomsich b4806d6f1f arm: provide a PCS-compliant setjmp implementation
The previous setjmp-implementation (as a static inline function that
contained an 'asm volatile' sequence) was extremely fragile: (some
versions of) GCC optimised the set of registers.  One critical example
was the removal of 'r9' from the clobber list, if -ffixed-reg9 was
supplied.

To increase robustness and ensure PCS-compliant behaviour, the setjmp
and longjmp implementation are now in assembly and closely match what
one would expect to find in a libc implementation.

Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Tested-by: Andy Yan <andy.yan@rock-chips.com>
2017-11-21 23:57:22 +01:00

42 lines
874 B
ArmAsm

/*
* (C) 2017 Theobroma Systems Design und Consulting GmbH
*
* SPDX-License-Identifier: GPL-2.0+
*/
#include <config.h>
#include <asm/macro.h>
#include <linux/linkage.h>
.pushsection .text.setjmp, "ax"
ENTRY(setjmp)
/* Preserve all callee-saved registers and the SP */
stp x19, x20, [x0,#0]
stp x21, x22, [x0,#16]
stp x23, x24, [x0,#32]
stp x25, x26, [x0,#48]
stp x27, x28, [x0,#64]
stp x29, x30, [x0,#80]
mov x2, sp
str x2, [x0, #96]
mov x0, #0
ret
ENDPROC(setjmp)
.popsection
.pushsection .text.longjmp, "ax"
ENTRY(longjmp)
ldp x19, x20, [x0,#0]
ldp x21, x22, [x0,#16]
ldp x23, x24, [x0,#32]
ldp x25, x26, [x0,#48]
ldp x27, x28, [x0,#64]
ldp x29, x30, [x0,#80]
ldr x2, [x0,#96]
mov sp, x2
/* Move the return value in place, but return 1 if passed 0. */
adds x0, xzr, x1
csinc x0, x0, xzr, ne
ret
ENDPROC(longjmp)
.popsection