From: Ira Weiny ira.weiny@intel.com
pkey_alloc() is documented to return ENOSPC when the hardware does not support pkeys. On x86, pkey_alloc() incorrectly returns EINVAL.
This is because mm_pkey_alloc() does not check for pkey support before returning a key. Therefore, if the keys are not exhausted pkey_alloc() continues on to call arch_set_user_pkey_access(). Unfortunately, when arch_set_user_pkey_access() detects the failed support it overwrites the ENOSPC return value with EINVAL.
Ensure consistent behavior across architectures by lifting this check to the core mm code.
Remove a couple of 'we' references in code comments as well.
Cc: ahaas@chromium.org Cc: clemensb@chromium.org Cc: gdeepti@chromium.org Cc: jkummerow@chromium.org Cc: manoskouk@chromium.org Cc: thibaudm@chromium.org Cc: Florian Weimer fweimer@redhat.com Cc: Sohil Mehta sohil.mehta@intel.com Cc: Andrew Morton akpm@linux-foundation.org Cc: Dave Hansen dave.hansen@linux.intel.com Cc: Aneesh Kumar K.V aneesh.kumar@linux.ibm.com Cc: linux-api@vger.kernel.org Fixes: e8c24d3a23a4 ("x86/pkeys: Allocation/free syscalls") Signed-off-by: Ira Weiny ira.weiny@intel.com
--- Thanks to Sohil for pointing out that the commit message could be more clear WRT how EINVAL is returned incorrectly. --- arch/powerpc/include/asm/pkeys.h | 8 +++----- mm/mprotect.c | 3 +++ 2 files changed, 6 insertions(+), 5 deletions(-)
diff --git a/arch/powerpc/include/asm/pkeys.h b/arch/powerpc/include/asm/pkeys.h index 59a2c7dbc78f..2c8351248793 100644 --- a/arch/powerpc/include/asm/pkeys.h +++ b/arch/powerpc/include/asm/pkeys.h @@ -85,18 +85,16 @@ static inline bool mm_pkey_is_allocated(struct mm_struct *mm, int pkey) static inline int mm_pkey_alloc(struct mm_struct *mm) { /* - * Note: this is the one and only place we make sure that the pkey is + * Note: this is the one and only place to make sure that the pkey is * valid as far as the hardware is concerned. The rest of the kernel * trusts that only good, valid pkeys come out of here. */ u32 all_pkeys_mask = (u32)(~(0x0)); int ret;
- if (!mmu_has_feature(MMU_FTR_PKEY)) - return -1; /* - * Are we out of pkeys? We must handle this specially because ffz() - * behavior is undefined if there are no zeros. + * Out of pkeys? Handle this specially because ffz() behavior is + * undefined if there are no zeros. */ if (mm_pkey_allocation_map(mm) == all_pkeys_mask) return -1; diff --git a/mm/mprotect.c b/mm/mprotect.c index ba5592655ee3..56d35de33725 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -773,6 +773,9 @@ SYSCALL_DEFINE2(pkey_alloc, unsigned long, flags, unsigned long, init_val) int pkey; int ret;
+ if (!arch_pkeys_enabled()) + return -ENOSPC; + /* No flags supported yet. */ if (flags) return -EINVAL;