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-   -   ARM: fix vtop -C for kernel addresses (http://www.linux-archive.org/crash-utility/642923-arm-fix-vtop-c-kernel-addresses.html)

Rabin Vincent 03-10-2012 11:04 AM

ARM: fix vtop -C for kernel addresses
 
On ARM, [vtop -C task] doesn't work correctly for kernel addresses: it
always uses swapper_pg_dir when it should be using the task's mm->pgd.

The patch below fixes this, and also makes ARM handle kernel threads
like the other arches.

Rabin

diff --git a/arm.c b/arm.c
index 4be224e..cac9a9a 100644
--- a/arm.c
+++ b/arm.c
@@ -1020,22 +1020,37 @@ static int
arm_uvtop(struct task_context *tc, ulong uvaddr, physaddr_t *paddr, int verbose)
{
ulong *pgd;
- ulong mm;

if (!tc)
error(FATAL, "current context invalid
");

*paddr = 0;

- if (IS_KVADDR(uvaddr))
- return arm_kvtop(tc, uvaddr, paddr, verbose);
+ if (is_kernel_thread(tc->task) && IS_KVADDR(uvaddr)) {
+ ulong active_mm;

- mm = task_mm(tc->task, TRUE);
- if (mm)
- pgd = ULONG_PTR(tt->mm_struct + OFFSET(mm_struct_pgd));
- else
- readmem(tc->mm_struct + OFFSET(mm_struct_pgd), KVADDR, &pgd,
- sizeof(long), "mm_struct pgd", FAULT_ON_ERROR);
+ readmem(tc->task + OFFSET(task_struct_active_mm),
+ KVADDR, &active_mm, sizeof(void *),
+ "task active_mm contents", FAULT_ON_ERROR);
+
+ if (!active_mm)
+ error(FATAL,
+ "no active_mm for this kernel thread
");
+
+ readmem(active_mm + OFFSET(mm_struct_pgd),
+ KVADDR, &pgd, sizeof(long),
+ "mm_struct pgd", FAULT_ON_ERROR);
+ } else {
+ ulong mm;
+
+ mm = task_mm(tc->task, TRUE);
+ if (mm)
+ pgd = ULONG_PTR(tt->mm_struct + OFFSET(mm_struct_pgd));
+ else
+ readmem(tc->mm_struct + OFFSET(mm_struct_pgd),
+ KVADDR, &pgd, sizeof(long), "mm_struct pgd",
+ FAULT_ON_ERROR);
+ }

return arm_vtop(uvaddr, pgd, paddr, verbose);
}

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Dave Anderson 03-12-2012 02:27 PM

ARM: fix vtop -C for kernel addresses
 
----- Original Message -----
> On ARM, [vtop -C task] doesn't work correctly for kernel addresses: it
> always uses swapper_pg_dir when it should be using the task's
> mm->pgd.
>
> The patch below fixes this, and also makes ARM handle kernel threads
> like the other arches.
>
> Rabin

The patch makes "vtop -c" conform with the other architectures, so unless
Mika has a problem with it, consider it queued for crash-6.0.5.

Thanks,
Dave


> diff --git a/arm.c b/arm.c
> index 4be224e..cac9a9a 100644
> --- a/arm.c
> +++ b/arm.c
> @@ -1020,22 +1020,37 @@ static int
> arm_uvtop(struct task_context *tc, ulong uvaddr, physaddr_t *paddr,
> int verbose)
> {
> ulong *pgd;
> - ulong mm;
>
> if (!tc)
> error(FATAL, "current context invalid
");
>
> *paddr = 0;
>
> - if (IS_KVADDR(uvaddr))
> - return arm_kvtop(tc, uvaddr, paddr, verbose);
> + if (is_kernel_thread(tc->task) && IS_KVADDR(uvaddr)) {
> + ulong active_mm;
>
> - mm = task_mm(tc->task, TRUE);
> - if (mm)
> - pgd = ULONG_PTR(tt->mm_struct + OFFSET(mm_struct_pgd));
> - else
> - readmem(tc->mm_struct + OFFSET(mm_struct_pgd), KVADDR, &pgd,
> - sizeof(long), "mm_struct pgd", FAULT_ON_ERROR);
> + readmem(tc->task + OFFSET(task_struct_active_mm),
> + KVADDR, &active_mm, sizeof(void *),
> + "task active_mm contents", FAULT_ON_ERROR);
> +
> + if (!active_mm)
> + error(FATAL,
> + "no active_mm for this kernel thread
");
> +
> + readmem(active_mm + OFFSET(mm_struct_pgd),
> + KVADDR, &pgd, sizeof(long),
> + "mm_struct pgd", FAULT_ON_ERROR);
> + } else {
> + ulong mm;
> +
> + mm = task_mm(tc->task, TRUE);
> + if (mm)
> + pgd = ULONG_PTR(tt->mm_struct + OFFSET(mm_struct_pgd));
> + else
> + readmem(tc->mm_struct + OFFSET(mm_struct_pgd),
> + KVADDR, &pgd, sizeof(long), "mm_struct pgd",
> + FAULT_ON_ERROR);
> + }
>
> return arm_vtop(uvaddr, pgd, paddr, verbose);
> }
>
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>

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