diff options
| author | Christophe Leroy <[email protected]> | 2023-07-11 17:59:19 +0200 |
|---|---|---|
| committer | Michael Ellerman <[email protected]> | 2023-08-02 22:22:18 +1000 |
| commit | 5222a1d5142ec4f9ec063b274b80e20639584dbc (patch) | |
| tree | e4210aa50b73e13b091ea8ed847ce1ffac84f4c2 /arch/powerpc/include/asm/bug.h | |
| parent | 26e041208291bfdea1cb9e26bc94a0f9499efe15 (diff) | |
powerpc/kuap: Simplify KUAP lock/unlock on BOOK3S/32
On book3s/32 KUAP is performed at segment level. At the moment,
when enabling userspace access, only current segment is modified.
Then if a write is performed on another user segment, a fault is
taken and all other user segments get enabled for userspace
access. This then require special attention when disabling
userspace access.
Having a userspace write access crossing a segment boundary is
unlikely. Having a userspace write access crossing a segment boundary
back and forth is even more unlikely. So, instead of enabling
userspace access on all segments when a write fault occurs, just
change which segment has userspace access enabled in order to
eliminate the case when more than one segment has userspace access
enabled. That simplifies userspace access deactivation.
There is however a corner case which is even more unlikely but has
to be handled anyway: an unaligned access which is crossing a
segment boundary. That would definitely require at least having
userspace access enabled on the two segments. To avoid complicating
the likely case for a so unlikely happening, handle such situation
like an alignment exception and emulate the store.
Signed-off-by: Christophe Leroy <[email protected]>
Signed-off-by: Michael Ellerman <[email protected]>
Link: https://msgid.link/8de8580513c1a6e880bad1ba9a69d3efad3d4fa5.1689091022.git.christophe.leroy@csgroup.eu
Diffstat (limited to 'arch/powerpc/include/asm/bug.h')
| -rw-r--r-- | arch/powerpc/include/asm/bug.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/bug.h b/arch/powerpc/include/asm/bug.h index 00c6b0b4ede4..1db485aacbd9 100644 --- a/arch/powerpc/include/asm/bug.h +++ b/arch/powerpc/include/asm/bug.h @@ -120,6 +120,7 @@ struct pt_regs; void hash__do_page_fault(struct pt_regs *); void bad_page_fault(struct pt_regs *, int); +void emulate_single_step(struct pt_regs *regs); extern void _exception(int, struct pt_regs *, int, unsigned long); extern void _exception_pkey(struct pt_regs *, unsigned long, int); extern void die(const char *, struct pt_regs *, long); |