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arm: Introduce setjmp/longjmp

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To quit an EFI application we will need logic to jump to the caller
of a function without returning from the function we called into,
so we need setjmp/longjmp functionality.

This patch introduces a trivial implementation of these that I
verified works on armv7, thumb2 and aarch64.

Signed-off-by: Alexander Graf <agraf@suse.de>
This commit is contained in:
Alexander Graf 2016-05-20 23:28:22 +02:00 committed by Tom Rini
parent 145510cc76
commit 97d44b1f5c
1 changed files with 99 additions and 0 deletions
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arch/arm/include/asm/setjmp.h Normal file
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/*
* (C) Copyright 2016
* Alexander Graf <agraf@suse.de>
*
* SPDX-License-Identifier: GPL-2.0+
*/
#ifndef _SETJMP_H_
#define _SETJMP_H_ 1
struct jmp_buf_data {
ulong target;
ulong regs[5];
};
typedef struct jmp_buf_data jmp_buf[1];
static inline int setjmp(jmp_buf jmp)
{
long r = 0;
#ifdef CONFIG_ARM64
asm volatile(
"adr x1, jmp_target\n"
"str x1, %1\n"
"stp x26, x27, %2\n"
"stp x28, x29, %3\n"
"mov x1, sp\n"
"str x1, %4\n"
"b 2f\n"
"jmp_target: "
"mov %0, #1\n"
"2:\n"
: "+r" (r), "=m" (jmp->target),
"=m" (jmp->regs[0]), "=m" (jmp->regs[2]),
"=m" (jmp->regs[4])
:
: "x0", "x1", "x2", "x3", "x4", "x5", "x6", "x7",
"x8", "x9", "x10", "x11", "x12", "x13", "x14", "x15",
"x16", "x17", "x18", "x19", "x20", "x21", "x22",
"x23", "x24", "x25", /* x26, x27, x28, x29, sp */
"x30", "cc", "memory");
#else
asm volatile(
#ifdef CONFIG_SYS_THUMB_BUILD
"adr r0, jmp_target + 1\n"
#else
"adr r0, jmp_target\n"
#endif
"mov r1, %1\n"
"mov r2, sp\n"
"stm r1, {r0, r2, r4, r5, r6, r7}\n"
"b 2f\n"
"jmp_target: "
"mov %0, #1\n"
"2:\n"
: "+l" (r)
: "l" (&jmp->target)
: "r0", "r1", "r2", "r3", /* "r4", "r5", "r6", "r7", */
"r8", "r9", "r10", "r11", /* sp, */ "ip", "lr",
"cc", "memory");
#endif
printf("%s:%d target=%#lx\n", __func__, __LINE__, jmp->target);
return r;
}
static inline __noreturn void longjmp(jmp_buf jmp)
{
#ifdef CONFIG_ARM64
asm volatile(
"ldr x0, %0\n"
"ldr x1, %3\n"
"mov sp, x1\n"
"ldp x26, x27, %1\n"
"ldp x28, x25, %2\n"
"mov x29, x25\n"
"br x0\n"
:
: "m" (jmp->target), "m" (jmp->regs[0]), "m" (jmp->regs[2]),
"m" (jmp->regs[4])
: "x0", "x1", "x25", "x26", "x27", "x28");
#else
asm volatile(
"mov r1, %0\n"
"ldm r1, {r0, r2, r4, r5, r6, r7}\n"
"mov sp, r2\n"
"bx r0\n"
:
: "l" (&jmp->target)
: "r1");
#endif
while (1) { }
}
#endif /* _SETJMP_H_ */