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yaml
---
r: 298835
b: refs/heads/master
c: 5f639fd
h: refs/heads/master
i:
  298833: aa302a2
  298831: 7c3654b
v: v3
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Chris Metcalf committed Apr 2, 2012
1 parent 79b9285 commit dd7a169
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Showing 3 changed files with 113 additions and 121 deletions.
2 changes: 1 addition & 1 deletion [refs]
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Original file line number Diff line number Diff line change
@@ -1,2 +1,2 @@
---
refs/heads/master: efb734d8ed040b053f53fd53589ed5d9c9b5cd04
refs/heads/master: 5f639fdcd8c186c8128c616e94a7e7b159c968ae
1 change: 0 additions & 1 deletion trunk/arch/tile/include/asm/stack.h
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Expand Up @@ -25,7 +25,6 @@
struct KBacktraceIterator {
BacktraceIterator it;
struct task_struct *task; /* task we are backtracing */
pte_t *pgtable; /* page table for user space access */
int end; /* iteration complete. */
int new_context; /* new context is starting */
int profile; /* profiling, so stop on async intrpt */
Expand Down
231 changes: 112 additions & 119 deletions trunk/arch/tile/kernel/stack.c
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Original file line number Diff line number Diff line change
Expand Up @@ -21,9 +21,10 @@
#include <linux/stacktrace.h>
#include <linux/uaccess.h>
#include <linux/mmzone.h>
#include <linux/dcache.h>
#include <linux/fs.h>
#include <asm/backtrace.h>
#include <asm/page.h>
#include <asm/tlbflush.h>
#include <asm/ucontext.h>
#include <asm/switch_to.h>
#include <asm/sigframe.h>
Expand All @@ -45,72 +46,23 @@ static int in_kernel_stack(struct KBacktraceIterator *kbt, unsigned long sp)
return sp >= kstack_base && sp < kstack_base + THREAD_SIZE;
}

/* Is address valid for reading? */
static int valid_address(struct KBacktraceIterator *kbt, unsigned long address)
{
HV_PTE *l1_pgtable = kbt->pgtable;
HV_PTE *l2_pgtable;
unsigned long pfn;
HV_PTE pte;
struct page *page;

if (l1_pgtable == NULL)
return 0; /* can't read user space in other tasks */

#ifdef CONFIG_64BIT
/* Find the real l1_pgtable by looking in the l0_pgtable. */
pte = l1_pgtable[HV_L0_INDEX(address)];
if (!hv_pte_get_present(pte))
return 0;
pfn = hv_pte_get_pfn(pte);
if (pte_huge(pte)) {
if (!pfn_valid(pfn)) {
pr_err("L0 huge page has bad pfn %#lx\n", pfn);
return 0;
}
return hv_pte_get_present(pte) && hv_pte_get_readable(pte);
}
page = pfn_to_page(pfn);
BUG_ON(PageHighMem(page)); /* No HIGHMEM on 64-bit. */
l1_pgtable = (HV_PTE *)pfn_to_kaddr(pfn);
#endif
pte = l1_pgtable[HV_L1_INDEX(address)];
if (!hv_pte_get_present(pte))
return 0;
pfn = hv_pte_get_pfn(pte);
if (pte_huge(pte)) {
if (!pfn_valid(pfn)) {
pr_err("huge page has bad pfn %#lx\n", pfn);
return 0;
}
return hv_pte_get_present(pte) && hv_pte_get_readable(pte);
}

page = pfn_to_page(pfn);
if (PageHighMem(page)) {
pr_err("L2 page table not in LOWMEM (%#llx)\n",
HV_PFN_TO_CPA(pfn));
return 0;
}
l2_pgtable = (HV_PTE *)pfn_to_kaddr(pfn);
pte = l2_pgtable[HV_L2_INDEX(address)];
return hv_pte_get_present(pte) && hv_pte_get_readable(pte);
}

/* Callback for backtracer; basically a glorified memcpy */
static bool read_memory_func(void *result, unsigned long address,
unsigned int size, void *vkbt)
{
int retval;
struct KBacktraceIterator *kbt = (struct KBacktraceIterator *)vkbt;

if (address == 0)
return 0;
if (__kernel_text_address(address)) {
/* OK to read kernel code. */
} else if (address >= PAGE_OFFSET) {
/* We only tolerate kernel-space reads of this task's stack */
if (!in_kernel_stack(kbt, address))
return 0;
} else if (!valid_address(kbt, address)) {
return 0; /* invalid user-space address */
} else if (!kbt->is_current) {
return 0; /* can't read from other user address spaces */
}
pagefault_disable();
retval = __copy_from_user_inatomic(result,
Expand All @@ -128,6 +80,8 @@ static struct pt_regs *valid_fault_handler(struct KBacktraceIterator* kbt)
unsigned long sp = kbt->it.sp;
struct pt_regs *p;

if (sp % sizeof(long) != 0)
return NULL;
if (!in_kernel_stack(kbt, sp))
return NULL;
if (!in_kernel_stack(kbt, sp + C_ABI_SAVE_AREA_SIZE + PTREGS_SIZE-1))
Expand Down Expand Up @@ -170,27 +124,27 @@ static int is_sigreturn(unsigned long pc)
}

/* Return a pt_regs pointer for a valid signal handler frame */
static struct pt_regs *valid_sigframe(struct KBacktraceIterator* kbt)
static struct pt_regs *valid_sigframe(struct KBacktraceIterator* kbt,
struct rt_sigframe* kframe)
{
BacktraceIterator *b = &kbt->it;

if (b->pc == VDSO_BASE) {
struct rt_sigframe *frame;
unsigned long sigframe_top =
b->sp + sizeof(struct rt_sigframe) - 1;
if (!valid_address(kbt, b->sp) ||
!valid_address(kbt, sigframe_top)) {
if (kbt->verbose)
pr_err(" (odd signal: sp %#lx?)\n",
(unsigned long)(b->sp));
if (b->pc == VDSO_BASE && b->sp < PAGE_OFFSET &&
b->sp % sizeof(long) == 0) {
int retval;
pagefault_disable();
retval = __copy_from_user_inatomic(
kframe, (void __user __force *)b->sp,
sizeof(*kframe));
pagefault_enable();
if (retval != 0 ||
(unsigned int)(kframe->info.si_signo) >= _NSIG)
return NULL;
}
frame = (struct rt_sigframe *)b->sp;
if (kbt->verbose) {
pr_err(" <received signal %d>\n",
frame->info.si_signo);
kframe->info.si_signo);
}
return (struct pt_regs *)&frame->uc.uc_mcontext;
return (struct pt_regs *)&kframe->uc.uc_mcontext;
}
return NULL;
}
Expand All @@ -203,10 +157,11 @@ static int KBacktraceIterator_is_sigreturn(struct KBacktraceIterator *kbt)
static int KBacktraceIterator_restart(struct KBacktraceIterator *kbt)
{
struct pt_regs *p;
struct rt_sigframe kframe;

p = valid_fault_handler(kbt);
if (p == NULL)
p = valid_sigframe(kbt);
p = valid_sigframe(kbt, &kframe);
if (p == NULL)
return 0;
backtrace_init(&kbt->it, read_memory_func, kbt,
Expand Down Expand Up @@ -266,41 +221,19 @@ void KBacktraceIterator_init(struct KBacktraceIterator *kbt,

/*
* 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.
* so we will allow reads of that address range.
*/
is_current = (t == NULL);
is_current = (t == NULL || t == current);
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();
kbt->new_context = 1;
if (is_current)
validate_stack(regs);
}

if (regs == NULL) {
if (is_current || t->state == TASK_RUNNING) {
Expand Down Expand Up @@ -346,6 +279,78 @@ void KBacktraceIterator_next(struct KBacktraceIterator *kbt)
}
EXPORT_SYMBOL(KBacktraceIterator_next);

static void describe_addr(struct KBacktraceIterator *kbt,
unsigned long address,
int have_mmap_sem, char *buf, size_t bufsize)
{
struct vm_area_struct *vma;
size_t namelen, remaining;
unsigned long size, offset, adjust;
char *p, *modname;
const char *name;
int rc;

/*
* Look one byte back for every caller frame (i.e. those that
* aren't a new context) so we look up symbol data for the
* call itself, not the following instruction, which may be on
* a different line (or in a different function).
*/
adjust = !kbt->new_context;
address -= adjust;

if (address >= PAGE_OFFSET) {
/* Handle kernel symbols. */
BUG_ON(bufsize < KSYM_NAME_LEN);
name = kallsyms_lookup(address, &size, &offset,
&modname, buf);
if (name == NULL) {
buf[0] = '\0';
return;
}
namelen = strlen(buf);
remaining = (bufsize - 1) - namelen;
p = buf + namelen;
rc = snprintf(p, remaining, "+%#lx/%#lx ",
offset + adjust, size);
if (modname && rc < remaining)
snprintf(p + rc, remaining - rc, "[%s] ", modname);
buf[bufsize-1] = '\0';
return;
}

/* If we don't have the mmap_sem, we can't show any more info. */
buf[0] = '\0';
if (!have_mmap_sem)
return;

/* Find vma info. */
vma = find_vma(kbt->task->mm, address);
if (vma == NULL || address < vma->vm_start) {
snprintf(buf, bufsize, "[unmapped address] ");
return;
}

if (vma->vm_file) {
char *s;
p = d_path(&vma->vm_file->f_path, buf, bufsize);
if (IS_ERR(p))
p = "?";
s = strrchr(p, '/');
if (s)
p = s+1;
} else {
p = "anon";
}

/* Generate a string description of the vma info. */
namelen = strlen(p);
remaining = (bufsize - 1) - namelen;
memmove(buf, p, namelen);
snprintf(buf + namelen, remaining, "[%lx+%lx] ",
vma->vm_start, vma->vm_end - vma->vm_start);
}

/*
* This method wraps the backtracer's more generic support.
* It is only invoked from the architecture-specific code; show_stack()
Expand All @@ -354,6 +359,7 @@ EXPORT_SYMBOL(KBacktraceIterator_next);
void tile_show_stack(struct KBacktraceIterator *kbt, int headers)
{
int i;
int have_mmap_sem = 0;

if (headers) {
/*
Expand All @@ -370,31 +376,16 @@ void tile_show_stack(struct KBacktraceIterator *kbt, int headers)
kbt->verbose = 1;
i = 0;
for (; !KBacktraceIterator_end(kbt); KBacktraceIterator_next(kbt)) {
char *modname;
const char *name;
unsigned long address = kbt->it.pc;
unsigned long offset, size;
char namebuf[KSYM_NAME_LEN+100];
unsigned long address = kbt->it.pc;

if (address >= PAGE_OFFSET)
name = kallsyms_lookup(address, &size, &offset,
&modname, namebuf);
else
name = NULL;

if (!name)
namebuf[0] = '\0';
else {
size_t namelen = strlen(namebuf);
size_t remaining = (sizeof(namebuf) - 1) - namelen;
char *p = namebuf + namelen;
int rc = snprintf(p, remaining, "+%#lx/%#lx ",
offset, size);
if (modname && rc < remaining)
snprintf(p + rc, remaining - rc,
"[%s] ", modname);
namebuf[sizeof(namebuf)-1] = '\0';
}
/* Try to acquire the mmap_sem as we pass into userspace. */
if (address < PAGE_OFFSET && !have_mmap_sem && kbt->task->mm)
have_mmap_sem =
down_read_trylock(&kbt->task->mm->mmap_sem);

describe_addr(kbt, address, have_mmap_sem,
namebuf, sizeof(namebuf));

pr_err(" frame %d: 0x%lx %s(sp 0x%lx)\n",
i++, address, namebuf, (unsigned long)(kbt->it.sp));
Expand All @@ -409,6 +400,8 @@ void tile_show_stack(struct KBacktraceIterator *kbt, int headers)
pr_err("Stack dump stopped; next frame identical to this one\n");
if (headers)
pr_err("Stack dump complete\n");
if (have_mmap_sem)
up_read(&kbt->task->mm->mmap_sem);
}
EXPORT_SYMBOL(tile_show_stack);

Expand Down

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