On Mon, May 21, 2018 at 01:29:11PM +0200, Florian Weimer wrote:
> On 05/20/2018 09:11 PM, Ram Pai wrote:
> >Florian,
> >
> > Does the following patch fix the problem for you? Just like x86
> > I am enabling all keys in the UAMOR register during
> > initialization itself. Hence any key created by any thread at
> > any time, will get activated on all threads. So any thread
> > can change the permission on that key. Smoke tested it
> > with your test program.
>
> I think this goes in the right direction, but the AMR value after
> fork is still strange:
>
> AMR (PID 34912): 0x0000000000000000
> AMR after fork (PID 34913): 0x0000000000000000
> AMR (PID 34913): 0x0000000000000000
> Allocated key in subprocess (PID 34913): 2
> Allocated key (PID 34912): 2
> Setting AMR: 0xffffffffffffffff
> New AMR value (PID 34912): 0x0fffffffffffffff
> About to call execl (PID 34912) ...
> AMR (PID 34912): 0x0fffffffffffffff
> AMR after fork (PID 34914): 0x0000000000000003
> AMR (PID 34914): 0x0000000000000003
> Allocated key in subprocess (PID 34914): 2
> Allocated key (PID 34912): 2
> Setting AMR: 0xffffffffffffffff
> New AMR value (PID 34912): 0x0fffffffffffffff
>
> I mean this line:
>
> AMR after fork (PID 34914): 0x0000000000000003
>
> Shouldn't it be the same as in the parent process?
Fixed it. Please try this patch. If it all works to your satisfaction, I
will clean it up further and send to Michael Ellermen(ppc maintainer).
commit 51f4208ed5baeab1edb9b0f8b68d7144449b3527
Author: Ram Pai <linuxram@xxxxxxxxxx>
Date: Sun Jun 3 14:44:32 2018 -0500
Fix for the fork bug.
Signed-off-by: Ram Pai <linuxram@xxxxxxxxxx>
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 1237f13..999dd08 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -582,6 +582,7 @@ static void save_all(struct task_struct *tsk)
__giveup_spe(tsk);
msr_check_and_clear(msr_all_available);
+ thread_pkey_regs_save(&tsk->thread);
}
void flush_all_to_thread(struct task_struct *tsk)
diff --git a/arch/powerpc/mm/pkeys.c b/arch/powerpc/mm/pkeys.c
index ab4519a..af6aa4a 100644
--- a/arch/powerpc/mm/pkeys.c
+++ b/arch/powerpc/mm/pkeys.c
@@ -294,6 +294,7 @@ void thread_pkey_regs_save(struct thread_struct *thread)
*/
thread->amr = read_amr();
thread->iamr = read_iamr();
+ thread->uamor = read_uamor();
}
void thread_pkey_regs_restore(struct thread_struct *new_thread,
@@ -315,9 +316,13 @@ void thread_pkey_regs_init(struct thread_struct *thread)
if (static_branch_likely(&pkey_disabled))
return;
- thread->amr = read_amr() & pkey_amr_mask;
- thread->iamr = read_iamr() & pkey_iamr_mask;
+ thread->amr = pkey_amr_mask;
+ thread->iamr = pkey_iamr_mask;
thread->uamor = pkey_uamor_mask;
+
+ write_uamor(pkey_uamor_mask);
+ write_amr(pkey_amr_mask);
+ write_iamr(pkey_iamr_mask);
}
static inline bool pkey_allows_readwrite(int pkey)
>
> Thanks,
> Florian
--
Ram Pai
