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author | Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2017-07-19 14:49:39 +1000 |
---|---|---|
committer | Michael Ellerman <mpe@ellerman.id.au> | 2017-08-03 16:06:49 +1000 |
commit | 2865d08dd9ea876524652f3900b4b3b9c8b22e77 (patch) | |
tree | b6d7f97159688c7a2ace2e3f1dc5bd21aa0feea1 /arch/powerpc/mm/fault.c | |
parent | 04aafdc6018feef590517b3900c19d911b8a456c (diff) | |
download | linux-2865d08dd9ea876524652f3900b4b3b9c8b22e77.tar.bz2 |
powerpc/mm: Move the DSISR_PROTFAULT sanity check
This has a page of comment explaining what's going on right in
the middle of do_page_fault() which makes things a bit hard to
follow. Move it to a helper instead. Also do the test earlier
as there's no point waiting until after we found the VMA.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/mm/fault.c')
-rw-r--r-- | arch/powerpc/mm/fault.c | 75 |
1 files changed, 42 insertions, 33 deletions
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c index bd5d668b47ff..6f3a2437008a 100644 --- a/arch/powerpc/mm/fault.c +++ b/arch/powerpc/mm/fault.c @@ -239,6 +239,45 @@ static inline void cmo_account_page_fault(void) static inline void cmo_account_page_fault(void) { } #endif /* CONFIG_PPC_SMLPAR */ +#ifdef CONFIG_PPC_STD_MMU +static void sanity_check_fault(bool is_write, unsigned long error_code) +{ + /* + * For hash translation mode, we should never get a + * PROTFAULT. Any update to pte to reduce access will result in us + * removing the hash page table entry, thus resulting in a DSISR_NOHPTE + * fault instead of DSISR_PROTFAULT. + * + * A pte update to relax the access will not result in a hash page table + * entry invalidate and hence can result in DSISR_PROTFAULT. + * ptep_set_access_flags() doesn't do a hpte flush. This is why we have + * the special !is_write in the below conditional. + * + * For platforms that doesn't supports coherent icache and do support + * per page noexec bit, we do setup things such that we do the + * sync between D/I cache via fault. But that is handled via low level + * hash fault code (hash_page_do_lazy_icache()) and we should not reach + * here in such case. + * + * For wrong access that can result in PROTFAULT, the above vma->vm_flags + * check should handle those and hence we should fall to the bad_area + * handling correctly. + * + * For embedded with per page exec support that doesn't support coherent + * icache we do get PROTFAULT and we handle that D/I cache sync in + * set_pte_at while taking the noexec/prot fault. Hence this is WARN_ON + * is conditional for server MMU. + * + * For radix, we can get prot fault for autonuma case, because radix + * page table will have them marked noaccess for user. + */ + if (!radix_enabled() && !is_write) + WARN_ON_ONCE(error_code & DSISR_PROTFAULT); +} +#else +static void sanity_check_fault(bool is_write, unsigned long error_code) { } +#endif /* CONFIG_PPC_STD_MMU */ + /* * Define the correct "is_write" bit in error_code based * on the processor family @@ -306,6 +345,9 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address, return SIGBUS; } + /* Additional sanity check(s) */ + sanity_check_fault(is_write, error_code); + /* * The kernel should never take an execute fault nor should it * take a page fault to a kernel address. @@ -441,39 +483,6 @@ good_area: if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))) return bad_area(regs, address); } -#ifdef CONFIG_PPC_STD_MMU - /* - * For hash translation mode, we should never get a - * PROTFAULT. Any update to pte to reduce access will result in us - * removing the hash page table entry, thus resulting in a DSISR_NOHPTE - * fault instead of DSISR_PROTFAULT. - * - * A pte update to relax the access will not result in a hash page table - * entry invalidate and hence can result in DSISR_PROTFAULT. - * ptep_set_access_flags() doesn't do a hpte flush. This is why we have - * the special !is_write in the below conditional. - * - * For platforms that doesn't supports coherent icache and do support - * per page noexec bit, we do setup things such that we do the - * sync between D/I cache via fault. But that is handled via low level - * hash fault code (hash_page_do_lazy_icache()) and we should not reach - * here in such case. - * - * For wrong access that can result in PROTFAULT, the above vma->vm_flags - * check should handle those and hence we should fall to the bad_area - * handling correctly. - * - * For embedded with per page exec support that doesn't support coherent - * icache we do get PROTFAULT and we handle that D/I cache sync in - * set_pte_at while taking the noexec/prot fault. Hence this is WARN_ON - * is conditional for server MMU. - * - * For radix, we can get prot fault for autonuma case, because radix - * page table will have them marked noaccess for user. - */ - if (!radix_enabled() && !is_write) - WARN_ON_ONCE(error_code & DSISR_PROTFAULT); -#endif /* CONFIG_PPC_STD_MMU */ /* * If for any reason at all we couldn't handle the fault, |