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powerpc/mm: Add some debug output when hash insertion fails

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This adds some debug output to our MMU hash code to print out some
useful debug data if the hypervisor refuses the insertion (which
should normally never happen).

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
This commit is contained in:
Benjamin Herrenschmidt 2010-07-23 10:31:13 +10:00
parent 171aa2caaa
commit 4b8692c022
3 changed files with 34 additions and 6 deletions
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4
arch/powerpc/include/asm/mmu-hash64.h
View File

@ -250,7 +250,9 @@ extern int hash_page(unsigned long ea, unsigned long access, unsigned long trap)
int __hash_page_huge(unsigned long ea, unsigned long access, unsigned long vsid,
pte_t *ptep, unsigned long trap, int local, int ssize,
unsigned int shift, unsigned int mmu_psize);
extern void hash_failure_debug(unsigned long ea, unsigned long access,
unsigned long vsid, unsigned long trap,
int ssize, int psize, unsigned long pte);
extern int htab_bolt_mapping(unsigned long vstart, unsigned long vend,
unsigned long pstart, unsigned long prot,
int psize, int ssize);

34
arch/powerpc/mm/hash_utils_64.c
View File

@ -871,6 +871,18 @@ static inline int subpage_protection(struct mm_struct *mm, unsigned long ea)
}
#endif
void hash_failure_debug(unsigned long ea, unsigned long access,
unsigned long vsid, unsigned long trap,
int ssize, int psize, unsigned long pte)
{
if (!printk_ratelimit())
return;
pr_info("mm: Hashing failure ! EA=0x%lx access=0x%lx current=%s\n",
ea, access, current->comm);
pr_info(" trap=0x%lx vsid=0x%lx ssize=%d psize=%d pte=0x%lx\n",
trap, vsid, ssize, psize, pte);
}
/* Result code is:
* 0 - handled
* 1 - normal page fault
@ -1036,6 +1048,12 @@ int hash_page(unsigned long ea, unsigned long access, unsigned long trap)
local, ssize, spp);
}
/* Dump some info in case of hash insertion failure, they should
* never happen so it is really useful to know if/when they do
*/
if (rc == -1)
hash_failure_debug(ea, access, vsid, trap, ssize, psize,
pte_val(*ptep));
#ifndef CONFIG_PPC_64K_PAGES
DBG_LOW(" o-pte: %016lx\n", pte_val(*ptep));
#else
@ -1054,8 +1072,7 @@ void hash_preload(struct mm_struct *mm, unsigned long ea,
void *pgdir;
pte_t *ptep;
unsigned long flags;
int local = 0;
int ssize;
int rc, ssize, local = 0;
BUG_ON(REGION_ID(ea) != USER_REGION_ID);
@ -1101,11 +1118,18 @@ void hash_preload(struct mm_struct *mm, unsigned long ea,
/* Hash it in */
#ifdef CONFIG_PPC_HAS_HASH_64K
if (mm->context.user_psize == MMU_PAGE_64K)
__hash_page_64K(ea, access, vsid, ptep, trap, local, ssize);
rc = __hash_page_64K(ea, access, vsid, ptep, trap, local, ssize);
else
#endif /* CONFIG_PPC_HAS_HASH_64K */
__hash_page_4K(ea, access, vsid, ptep, trap, local, ssize,
subpage_protection(pgdir, ea));
rc = __hash_page_4K(ea, access, vsid, ptep, trap, local, ssize,
subpage_protection(pgdir, ea));
/* Dump some info in case of hash insertion failure, they should
* never happen so it is really useful to know if/when they do
*/
if (rc == -1)
hash_failure_debug(ea, access, vsid, trap, ssize,
mm->context.user_psize, pte_val(*ptep));
local_irq_restore(flags);
}

2
arch/powerpc/mm/hugetlbpage-hash64.c
View File

@ -127,6 +127,8 @@ repeat:
*/
if (unlikely(slot == -2)) {
*ptep = __pte(old_pte);
hash_failure_debug(ea, access, vsid, trap, ssize,
mmu_psize, old_pte);
return -1;
}