Commit 1693644d authored by Andrew Jones's avatar Andrew Jones Committed by Marcelo Tosatti
Browse files

arm/arm64: introduce thread_info

For smp we need a way to maintain thread local state. The bottom
of the thread stack is a good place, and is where Linux puts it.
So we just steal the concept of the thread_info structure that
lives at the bottom of the stack in Linux, and introduce it to
kvm-unit-tests/arm[64]. For starters we just have cpu index for
state, and that's implicitly initialized to zero for CPU0 already.
So, as we don't have secondary cpus yet, there's not much to do.

Additionally, sneak a small fixup in to the initial stack setup
for arm64. We were assuming that spsel is EL1 after reset, which
has been true so far, but let's not assume.

Signed-off-by: Andrew Jones's avatarAndrew Jones <>
Signed-off-by: default avatarMarcelo Tosatti <>
parent b13b47ed
......@@ -27,7 +27,7 @@ start:
* put the dtb in r0. This allows setup to be consistent
* with arm64.
ldr sp, =stacktop
ldr sp, =stackptr
mov r0, r2
push {r0-r1}
......@@ -21,7 +21,10 @@ start:
* The physical address of the dtb is in x0, x1-x3 are reserved
* See the kernel doc Documentation/arm64/booting.txt
adr x4, stacktop
mov x4, #1
msr spsel, x4
adr x4, stackptr
mov sp, x4
stp x0, x1, [sp, #-16]!
......@@ -18,6 +18,12 @@ SECTIONS
edata = .;
. += 64K;
. = ALIGN(64K);
* stack depth is ~16K, see THREAD_SIZE
* sp must be 16 byte aligned for arm64, and 8 byte aligned for arm
* sp must always be strictly less than the true stacktop
stackptr = . - 16;
stacktop = .;
......@@ -11,7 +11,7 @@
#include <asm/ptrace.h>
#include <asm/asm-offsets.h>
#include <asm/processor.h>
#include <asm/page.h>
#include <asm/thread_info.h>
static void assert_args(int num_args, int needed_args)
......@@ -313,9 +313,9 @@ int main(int argc, char **argv)
} else if (strcmp(argv[0], "vectors-user") == 0) {
void *sp = memalign(PAGE_SIZE, PAGE_SIZE);
memset(sp, 0, PAGE_SIZE);
start_usr(check_vectors, NULL, (unsigned long)sp + PAGE_SIZE);
void *sp = memalign(THREAD_SIZE, THREAD_SIZE);
start_usr(check_vectors, NULL,
(unsigned long)sp + THREAD_START_SP);
return report_summary();
* Adapted from arch/arm64/include/asm/thread_info.h
* Copyright (C) 2015, Red Hat Inc, Andrew Jones <>
* This work is licensed under the terms of the GNU LGPL, version 2.
#define THREAD_SIZE 16384
struct thread_info {
int cpu;
char ext[0]; /* allow unit tests to add extended info */
register unsigned long current_stack_pointer asm("sp");
static inline struct thread_info *current_thread_info(void)
return (struct thread_info *)
(current_stack_pointer & ~(THREAD_SIZE - 1));
#endif /* _ASMARM_THREAD_INFO_H_ */
#include "../../arm/asm/thread_info.h"
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