# \[PATCH 1/9\] x86, pkeys: add fault handling for PF\_PK page fault bit - From: Dave Hansen \ - Date: 2016-07-07 12:50:15 - List: linux-api - Page: https://ratatoskr.run/linux-api/2016/07/4790133 - Thread: https://ratatoskr.run/linux-api/2016/07/4790123/t.md ```text From: Dave Hansen PF_PK means that a memory access violated the protection key access restrictions. It is unconditionally an access_error() because the permissions set on the VMA don't matter (the PKRU value overrides it), and we never "resolve" PK faults (like how a COW can "resolve write fault). Signed-off-by: Dave Hansen Cc: Cc: Cc: Cc: x86@kernel.org Cc: torvalds@linux-foundation.org Cc: akpm@linux-foundation.org Cc: Arnd Bergmann Cc: Cc: hughd@google.com Cc: viro@zeniv.linux.org.uk --- b/arch/x86/mm/fault.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff -puN arch/x86/mm/fault.c~pkeys-105-add-pk-to-fault arch/x86/mm/fault.c --- a/arch/x86/mm/fault.c~pkeys-105-add-pk-to-fault 2016-07-07 05:46:59.554745699 -0700 +++ b/arch/x86/mm/fault.c 2016-07-07 05:46:59.558745881 -0700 @@ -1112,6 +1112,15 @@ access_error(unsigned long error_code, s { /* This is only called for the current mm, so: */ bool foreign = false; + + /* + * Read or write was blocked by protection keys. This is + * always an unconditional error and can never result in + * a follow-up action to resolve the fault, like a COW. + */ + if (error_code & PF_PK) + return 1; + /* * Make sure to check the VMA so that we do not perform * faults just to hit a PF_PK as soon as we fill in a _ -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org ```