// TODO verify coprocessor handling
/*
* arch/xtensa/kernel/process.c
*
* Xtensa Processor version.
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 2001 - 2005 Tensilica Inc.
*
* Joe Taylor <joe@tensilica.com, joetylr@yahoo.com>
* Chris Zankel <chris@zankel.net>
* Marc Gauthier <marc@tensilica.com, marc@alumni.uwaterloo.ca>
* Kevin Chea
*/
#include <linux/config.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <linux/ptrace.h>
#include <linux/slab.h>
#include <linux/elf.h>
#include <linux/init.h>
#include <linux/prctl.h>
#include <linux/init_task.h>
#include <linux/module.h>
#include <linux/mqueue.h>
#include <asm/pgtable.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#include <asm/io.h>
#include <asm/processor.h>
#include <asm/platform.h>
#include <asm/mmu.h>
#include <asm/irq.h>
#include <asm/atomic.h>
#include <asm/asm-offsets.h>
#include <asm/coprocessor.h>
extern void ret_from_fork(void);
static struct fs_struct init_fs = INIT_FS;
static struct files_struct init_files = INIT_FILES;
static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
struct mm_struct init_mm = INIT_MM(init_mm);
EXPORT_SYMBOL(init_mm);
union thread_union init_thread_union
__attribute__((__section__(".data.init_task"))) =
{ INIT_THREAD_INFO(init_task) };
struct task_struct init_task = INIT_TASK(init_task);
EXPORT_SYMBOL(init_task);
struct task_struct *current_set[NR_CPUS] = {&init_task, };
#if XCHAL_CP_NUM > 0
/*
* Coprocessor ownership.
*/
coprocessor_info_t coprocessor_info[] = {
{ 0, XTENSA_CPE_CP0_OFFSET },
{ 0, XTENSA_CPE_CP1_OFFSET },
{ 0, XTENSA_CPE_CP2_OFFSET },
{ 0, XTENSA_CPE_CP3_OFFSET },
{ 0, XTENSA_CPE_CP4_OFFSET },
{ 0, XTENSA_CPE_CP5_OFFSET },
{ 0, XTENSA_CPE_CP6_OFFSET },
{ 0, XTENSA_CPE_CP7_OFFSET },
};
#endif
/*
* Powermanagement idle function, if any is provided by the platform.
*/
void cpu_idle(void)
{
local_irq_enable();
/* endless idle loop with no priority at all */
while (1) {
while (!need_resched())
platform_idle();
preempt_enable();
schedule();
}
}
/*
* Free current thread data structures etc..
*/
void exit_thread(void)
{
release_coprocessors(current); /* Empty macro if no CPs are defined */
}
void flush_thread(void)
{
release_coprocessors(current); /* Empty macro if no CPs are defined */
}
/*
* Copy thread.
*
* The stack layout for the new thread looks like this:
*
* +------------------------+ <- sp in childregs (= tos)
* | childregs |
* +------------------------+ <- thread.sp = sp in dummy-frame
* | dummy-frame | (saved in dummy-frame spill-area)
* +------------------------+
*
* We create a dummy frame to return to ret_from_fork:
* a0 points to ret_from_fork (simulating a call4)
* sp points to itself (thread.sp)
* a2, a3 are unused.
*
* Note: This is a pristine frame, so we don't need any spill region on top of
* childregs.
*/
int copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
unsigned long unused,
struct task_struct * p, struct pt_regs * regs)
{
struct pt_regs *childregs;
unsigned long tos;
int user_mode = user_mode(regs);
/* Set up new TSS. */
tos = (unsigned long)p->thread_info + THREAD_SIZE;
if (user_mode)
childregs = (struct pt_regs*)(tos - PT_USER_SIZE);
else
childregs = (struct pt_regs*)tos - 1;
*childregs = *regs;
/* Create a call4 dummy-frame: a0 = 0, a1 = childregs. */
*((int*)childregs - 3) = (unsigned long)childregs;
*((int*)childregs - 4) = 0;
childregs->areg[1] = tos;
childregs->areg[2] = 0;
p->set_child_tid = p->clear_child_tid = NULL;
p->thread.ra = MAKE_RA_FOR_CALL((unsigned long)ret_from_fork, 0x1);
p->thread.sp = (unsigned long)childregs;
if (user_mode(regs)) {
int len = childregs->wmask & ~0xf;
childregs->areg[1] = usp;
memcpy(&childregs->areg[XCHAL_NUM_AREGS - len/4],
®s->areg[XCHAL_NUM_AREGS - len/4], len);
if (clone_flags & CLONE_SETTLS)
childregs->areg[2] = childregs->areg[6];
} else {
/* In kernel space, we start a new thread with a new stack. */
childregs->wmask = 1;
}
return 0;
}
/*
* Create a kernel thread
*/
int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
{
long retval;
__asm__ __volatile__
("mov a5, %4\n\t" /* preserve fn in a5 */
"mov a6, %3\n\t" /* preserve and setup arg in a6 */
"movi a2, %1\n\t" /* load __NR_clone for syscall*/
"mov a3, sp\n\t" /* sp check and sys_clone */
"mov a4, %5\n\t" /* load flags for syscall */
"syscall\n\t"
"beq a3, sp, 1f\n\t" /* branch if parent */
"callx4 a5\n\t" /* call fn */
"movi a2, %2\n\t" /* load __NR_exit for syscall */
"mov a3, a6\n\t" /* load fn return value */
"syscall\n"
"1:\n\t"
"mov %0, a2\n\t" /* parent returns zero */
:"=r" (retval)
:"i" (__NR_clone), "i" (__NR_exit),
"r" (arg), "r" (fn),
"r" (flags | CLONE_VM)
: "a2", "a3", "a4", "a5", "a6" );
return retval;
}
/*
* These bracket the sleeping functions..
*/
unsigned long get_wchan(struct task_struct *p)
{
unsigned long sp, pc;
unsigned long stack_page = (unsigned long) p->thread_info;
int count = 0;
if (!p || p == current || p->state == TASK_RUNNING)
return 0;
sp = p->thread.sp;
pc = MAKE_PC_FROM_RA(p->thread.ra, p->thread.sp);
do {
if (sp < stack_page + sizeof(struct task_struct) ||
sp >= (stack_page + THREAD_SIZE) ||
pc == 0)
return 0;
if (!in_sched_functions(pc))
return pc;
/* Stack layout: sp-4: ra, sp-3: sp' */
pc = MAKE_PC_FROM_RA(*(unsigned long*)sp - 4, sp);
sp = *(unsigned long *)sp - 3;
} while (count++ < 16);
return 0;
}
/*
* do_copy_regs() gathers information from 'struct pt_regs' and
* 'current->thread.areg[]' to fill in the xtensa_gregset_t
* structure.
*
* xtensa_gregset_t and 'struct pt_regs' are vastly different formats
* of processor registers. Besides different ordering,
* xtensa_gregset_t contains non-live register information that
* 'struct pt_regs' does not. Exception handling (primarily) uses
* 'struct pt_regs'. Core files and ptrace use xtensa_gregset_t.
*
*/
void do_copy_regs (xtensa_gregset_t *elfregs, struct pt_regs *regs,
struct task_struct *tsk)
{
int i, n, wb_offset;
elfregs->xchal_config_id0 = XCHAL_HW_CONFIGID0;
elfregs->xchal_config_id1 = XCHAL_HW_CONFIGID1;
__asm__ __volatile__ ("rsr %0, 176\n" : "=a" (i));
elfregs->cpux = i;
__asm__ __volatile__ ("rsr %0, 208\n" : "=a" (i));
elfregs->cpuy = i;
/* Note: PS.EXCM is not set while user task is running; its
* being set in regs->ps is for exception handling convenience.
*/
elfregs->pc = regs->pc;
elfregs->ps = (regs->ps & ~XCHAL_PS_EXCM_MASK);
elfregs->exccause = regs->exccause;
elfregs->excvaddr = regs->excvaddr;
elfregs->windowbase = regs->windowbase;
elfregs->windowstart = regs->windowstart;
elfregs->lbeg = regs->lbeg;
elfregs->lend = regs->lend;
elfregs->lcount = regs->lcount;
elfregs->sar = regs->sar;
elfregs->syscall = regs->syscall;
/* Copy register file.
* The layout looks like this:
*
* | a0 ... a15 | Z ... Z | arX ... arY |
* current window unused saved frames
*/
memset (elfregs->ar, 0, sizeof(elfregs->ar));
wb_offset = regs->windowbase * 4;
n = (regs->wmask&1)? 4 : (regs->wmask&2)? 8 : (regs->wmask&4)? 12 : 16;
for (i = 0; i < n; i++)
elfregs->ar[(wb_offset + i) % XCHAL_NUM_AREGS] = regs->areg[i];
n = (regs->wmask >> 4) * 4;
for (i = XCHAL_NUM_AREGS - n; n > 0; i++, n--)
elfregs->ar[(wb_offset + i) % XCHAL_NUM_AREGS] = regs->areg[i];
}
void xtensa_elf_core_copy_regs (xtensa_gregset_t *elfregs, struct pt_regs *regs)
{
do_copy_regs ((xtensa_gregset_t *)elfregs, regs, current);
}
/* The inverse of do_copy_regs(). No error or sanity checking. */
void do_restore_regs (xtensa_gregset_t *elfregs, struct pt_regs *regs,
struct task_struct *tsk)
{
int i, n, wb_offset;
/* Note: PS.EXCM is not set while user task is running; it
* needs to be set in regs->ps is for exception handling convenience.
*/
regs->pc = elfregs->pc;
regs->ps = (elfregs->ps | XCHAL_PS_EXCM_MASK);
regs->exccause = elfregs->exccause;
regs->excvaddr = elfregs->excvaddr;
regs->windowbase = elfregs->windowbase;
regs->windowstart = elfregs->windowstart;
regs->lbeg = elfregs->lbeg;
regs->lend = elfregs->lend;
regs->lcount = elfregs->lcount;
regs->sar = elfregs->sar;
regs->syscall = elfregs->syscall;
/* Clear everything. */
memset (regs->areg, 0, sizeof(regs->areg));
/* Copy regs from live window frame. */
wb_offset = regs->windowbase * 4;
n = (regs->wmask&1)? 4 : (regs->wmask&2)? 8 : (regs->wmask&4)? 12 : 16;
for (i = 0; i < n; i++)
regs->areg[(wb_offset+i) % XCHAL_NUM_AREGS] = elfregs->ar[i];
n = (regs->wmask >> 4) * 4;
for (i = XCHAL_NUM_AREGS - n; n > 0; i++, n--)
regs->areg[(wb_offset+i) % XCHAL_NUM_AREGS] = elfregs->ar[i];
}
/*
* do_save_fpregs() gathers information from 'struct pt_regs' and
* 'current->thread' to fill in the elf_fpregset_t structure.
*
* Core files and ptrace use elf_fpregset_t.
*/
void do_save_fpregs (elf_fpregset_t *fpregs, struct pt_regs *regs,
struct task_struct *tsk)
{
#if XCHAL_HAVE_CP
extern unsigned char _xtensa_reginfo_tables[];
extern unsigned _xtensa_reginfo_table_size;
int i;
unsigned long flags;
/* Before dumping coprocessor state from memory,
* ensure any live coprocessor contents for this
* task are first saved to memory:
*/
local_irq_save(flags);
for (i = 0; i < XCHAL_CP_MAX; i++) {
if (tsk == coprocessor_info[i].owner) {
enable_coprocessor(i);
save_coprocessor_registers(
tsk->thread.cp_save+coprocessor_info[i].offset,i);
disable_coprocessor(i);
}
}
local_irq_restore(flags);
/* Now dump coprocessor & extra state: */
memcpy((unsigned char*)fpregs,
_xtensa_reginfo_tables, _xtensa_reginfo_table_size);
memcpy((unsigned char*)fpregs + _xtensa_reginfo_table_size,
tsk->thread.cp_save, XTENSA_CP_EXTRA_SIZE);
#endif
}
/*
* The inverse of do_save_fpregs().
* Copies coprocessor and extra state from fpregs into regs and tsk->thread.
* Returns 0 on success, non-zero if layout doesn't match.
*/
int do_restore_fpregs (elf_fpregset_t *fpregs, struct pt_regs *regs,
struct task_struct *tsk)
{
#if XCHAL_HAVE_CP
extern unsigned char _xtensa_reginfo_tables[];
extern unsigned _xtensa_reginfo_table_size;
int i;
unsigned long flags;
/* Make sure save area layouts match.
* FIXME: in the future we could allow restoring from
* a different layout of the same registers, by comparing
* fpregs' table with _xtensa_reginfo_tables and matching
* entries and copying registers one at a time.
* Not too sure yet whether that's very useful.
*/
if( memcmp((unsigned char*)fpregs,
_xtensa_reginfo_tables, _xtensa_reginfo_table_size) ) {
return -1;
}
/* Before restoring coprocessor state from memory,
* ensure any live coprocessor contents for this
* task are first invalidated.
*/
local_irq_save(flags);
for (i = 0; i < XCHAL_CP_MAX; i++) {
if (tsk == coprocessor_info[i].owner) {
enable_coprocessor(i);
save_coprocessor_registers(
tsk->thread.cp_save+coprocessor_info[i].offset,i);
coprocessor_info[i].owner = 0;
disable_coprocessor(i);
}
}
local_irq_restore(flags);
/* Now restore coprocessor & extra state: */
memcpy(tsk->thread.cp_save,
(unsigned char*)fpregs + _xtensa_reginfo_table_size,
XTENSA_CP_EXTRA_SIZE);
#endif
return 0;
}
/*
* Fill in the CP structure for a core dump for a particular task.
*/
int
dump_task_fpu(struct pt_regs *regs, struct task_struct *task, elf_fpregset_t *r)
{
/* see asm/coprocessor.h for this magic number 16 */
#if TOTAL_CPEXTRA_SIZE > 16
do_save_fpregs (r, regs, task);
/* For now, bit 16 means some extra state may be present: */
// FIXME!! need to track to return more accurate mask
return 0x10000 | XCHAL_CP_MASK;
#else
return 0; /* no coprocessors active on this processor */
#endif
}
/*
* Fill in the CP structure for a core dump.
* This includes any FPU coprocessor.
* Here, we dump all coprocessors, and other ("extra") custom state.
*
* This function is called by elf_core_dump() in fs/binfmt_elf.c
* (in which case 'regs' comes from calls to do_coredump, see signals.c).
*/
int dump_fpu(struct pt_regs *regs, elf_fpregset_t *r)
{
return dump_task_fpu(regs, current, r);
}
