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um: Move uml_postsetup in the init_thread stack 

atomic_notifier_chain_register() and uml_postsetup() do call kernel code
that rely on the "current" kernel macro and a valid task_struct resp.
thread_info struct. Give those functions a valid stack by moving
uml_postsetup() in the init_thread stack. This moves enables a panic()
call in this early code to generate a valid stacktrace, instead of
crashing.
E.g. when an UML kernel is started with an initrd but too few physical
memory the panic() call get's actually processed.

Signed-off-by: Thomas Meyer <thomas@m3y3r.de>
Signed-off-by: Richard Weinberger <richard@nod.at>
This commit is contained in:
Thomas Meyer 2015-03-28 09:59:46 +01:00 committed by Richard Weinberger
parent 04a418495e
commit 33bbc30654
3 changed files with 12 additions and 6 deletions
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1
arch/um/include/shared/as-layout.h
View File

@ -56,6 +56,7 @@ extern unsigned long brk_start;
extern unsigned long host_task_size;
extern int linux_main(int argc, char **argv);
extern void uml_finishsetup(void);
struct siginfo;
extern void (*sig_info[])(int, struct siginfo *si, struct uml_pt_regs *);

15
arch/um/kernel/um_arch.c
View File

@ -226,6 +226,16 @@ static struct notifier_block panic_exit_notifier = {
.priority = 0
};
void uml_finishsetup(void)
{
atomic_notifier_chain_register(&panic_notifier_list,
&panic_exit_notifier);
uml_postsetup();
new_thread_handler();
}
/* Set during early boot */
unsigned long task_size;
EXPORT_SYMBOL(task_size);
@ -326,11 +336,6 @@ int __init linux_main(int argc, char **argv)
printf("Kernel virtual memory size shrunk to %lu bytes\n",
virtmem_size);
atomic_notifier_chain_register(&panic_notifier_list,
&panic_exit_notifier);
uml_postsetup();
stack_protections((unsigned long) &init_thread_info);
os_flush_stdout();

2
arch/um/os-Linux/skas/process.c
View File

@ -586,7 +586,7 @@ int start_idle_thread(void *stack, jmp_buf *switch_buf)
n = setjmp(initial_jmpbuf);
switch (n) {
case INIT_JMP_NEW_THREAD:
(*switch_buf)[0].JB_IP = (unsigned long) new_thread_handler;
(*switch_buf)[0].JB_IP = (unsigned long) uml_finishsetup;
(*switch_buf)[0].JB_SP = (unsigned long) stack +
UM_THREAD_SIZE - sizeof(void *);
break;