Re: [PATCH] powerpc/pkeys: copy pkey-tracking-information at fork()
From: Michael Ellerman <mpe@ellerman.id.au>
Date: 2018-12-20 13:21:34
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Michael Ellerman, Linus Torvalds
Hi Ram, Thanks for fixing this. Ram Pai [off-list ref] writes:
quoted hunk ↗ jump to hunk
diff --git a/arch/powerpc/mm/pkeys.c b/arch/powerpc/mm/pkeys.c index b271b28..5d65c47 100644 --- a/arch/powerpc/mm/pkeys.c +++ b/arch/powerpc/mm/pkeys.c@@ -414,3 +414,10 @@ bool arch_vma_access_permitted(struct vm_area_struct *vma, bool write, return pkey_access_permitted(vma_pkey(vma), write, execute); } + +void arch_dup_pkeys(struct mm_struct *oldmm, struct mm_struct *mm) +{ + /* Duplicate the oldmm pkey state in mm: */ + mm_pkey_allocation_map(mm) = mm_pkey_allocation_map(oldmm); + mm->context.execute_only_pkey = oldmm->context.execute_only_pkey; +}
Shouldn't this check if pkeys are actually in use? eg:
diff --git a/arch/powerpc/mm/pkeys.c b/arch/powerpc/mm/pkeys.c
index cf87dddefbdc..587807763737 100644
--- a/arch/powerpc/mm/pkeys.c
+++ b/arch/powerpc/mm/pkeys.c@@ -418,6 +418,9 @@ bool arch_vma_access_permitted(struct vm_area_struct *vma, bool write, void arch_dup_pkeys(struct mm_struct *oldmm, struct mm_struct *mm) { + if (static_branch_likely(&pkey_disabled)) + return; + /* Duplicate the oldmm pkey state in mm: */ mm_pkey_allocation_map(mm) = mm_pkey_allocation_map(oldmm); mm->context.execute_only_pkey = oldmm->context.execute_only_pkey;
Ideally we'd actually do it in the inline so that the function call to arch_dup_pkeys() can be avoided. But it looks like header dependencies might make that hard. cheers