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SubjectRe: [patch 00/12] Syslets, Threadlets, generic AIO support, v5

Hi Ingo,

> this is the v5 release of the syslet/threadlet subsystem:


I tried to port this to ppc64 but found a few problems:

The 64bit powerpc ABI has the concept of a TOC (r2) which is used for
per function data. This means this wont work:

if (ah->restore_stack) {
set_task_stack_reg(new_task, ah->restore_stack);
task_ip_reg(new_task) = ah->restore_ip;
* The return code 0 is needed to tell the
* head user-context that the threadlet went async:
task_ret_reg(new_task) = 0;

I think we would want to change restore_ip to restore_function, and then
create a per arch helper, perhaps:

void set_user_context(struct task_struct *task, unsigned long stack,
unsigned long function, unsigned long retval);

ppc64 could then grab the ip and r2 values from the function descriptor.

The other issue involves the syscall table:

asmlinkage struct syslet_uatom __user *
sys_async_exec(struct syslet_uatom __user *uatom,
struct async_head_user __user *ahu)
return __sys_async_exec(uatom, ahu, sys_call_table, NR_syscalls);

This exposes the layout of the syscall table. Unfortunately it wont work
on ppc64. In arch/powerpc/kernel/systbl.S:

#define COMPAT_SYS(func) .llong .sys_##func,.compat_sys_##func

Both syscall tables are overlaid.

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