Re: [PATCH] mprotect.2: pkey_mprotect acts like mprotect if pkey is set to -1, not 0.

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Hello Mark,

On 5/30/19 1:08 AM, Mark Wielaard wrote:
The mprotect.2 NOTES say:

   On systems that do not support protection keys in hardware,
   pkey_mprotect() may still be used, but pkey must be set to 0.  When
   called this way, the operation of pkey_mprotect() is equivalent to
   mprotect().

But this is not what the glibc manual says:

   It is also possible to call pkey_mprotect with a key value of -1,
   in which case it will behave in the same way as mprotect.

Which is correct. Both the glibc implementation and the kernel check
whether pkey is -1. 0 is not a valid pkey when memory protection keys
are not supported in hardware.

Signed-off-by: Mark Wielaard <mark@xxxxxxxxx>

Thanks. Patch applied.

Cheers,

Michael

---
  man2/mprotect.2 | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/man2/mprotect.2 b/man2/mprotect.2
index 4d29f66..866ac77 100644
--- a/man2/mprotect.2
+++ b/man2/mprotect.2
@@ -278,7 +278,7 @@ On systems that do not support protection keys in hardware,
  .BR pkey_mprotect ()
  may still be used, but
  .IR pkey
-must be set to 0.
+must be set to -1.
  When called this way, the operation of
  .BR pkey_mprotect ()
  is equivalent to




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