/*
* It's not generally safe to use "current" to get the page table pointer,
* since we might be running an oprofile interrupt in the middle of a
* task switch.
*/
static pgd_t *get_current_pgd(void)
{
HV_Context ctx = hv_inquire_context();
unsigned long pgd_pfn = ctx.page_table >> PAGE_SHIFT;
struct page *pgd_page = pfn_to_page(pgd_pfn);
BUG_ON(PageHighMem(pgd_page)); /* oops, HIGHPTE? */
return (pgd_t *) __va(ctx.page_table);
}
void KBacktraceIterator_init(struct KBacktraceIterator *kbt,
struct task_struct *t, struct pt_regs *regs)
{
unsigned long pc, lr, sp, r52;
int is_current;
/*
* Set up callback information. We grab the kernel stack base
* so we will allow reads of that address range, and if we're
* asking about the current process we grab the page table
* so we can check user accesses before trying to read them.
* We flush the TLB to avoid any weird skew issues.
*/
is_current = (t == NULL);
kbt->is_current = is_current;
if (is_current)
t = validate_current();
kbt->task = t;
kbt->pgtable = NULL;
kbt->verbose = 0; /* override in caller if desired */
kbt->profile = 0; /* override in caller if desired */
kbt->end = KBT_ONGOING;
kbt->new_context = 0;
if (is_current) {
HV_PhysAddr pgdir_pa = hv_inquire_context().page_table;
if (pgdir_pa == (unsigned long)swapper_pg_dir - PAGE_OFFSET) {
/*
* Not just an optimization: this also allows
* this to work at all before va/pa mappings
* are set up.
*/
kbt->pgtable = swapper_pg_dir;
} else {
struct page *page = pfn_to_page(PFN_DOWN(pgdir_pa));
if (!PageHighMem(page))
kbt->pgtable = __va(pgdir_pa);
else
pr_err("page table not in LOWMEM"
" (%#llx)\n", pgdir_pa);
}
local_flush_tlb_all();
validate_stack(regs);
}
if (regs == NULL) {
if (is_current || t->state == TASK_RUNNING) {
/* Can't do this; we need registers */
kbt->end = KBT_RUNNING;
return;
}
pc = get_switch_to_pc();
lr = t->thread.pc;
sp = t->thread.ksp;
r52 = 0;
} else {
pc = regs->pc;
lr = regs->lr;
sp = regs->sp;
r52 = regs->regs[52];
}
backtrace_init(&kbt->it, read_memory_func, kbt, pc, lr, sp, r52);
kbt->end = KBacktraceIterator_next_item_inclusive(kbt);
}
