diff options
author | Christophe Leroy <christophe.leroy@c-s.fr> | 2020-01-24 14:54:45 +0300 |
---|---|---|
committer | Michael Ellerman <mpe@ellerman.id.au> | 2020-01-28 15:14:44 +0300 |
commit | 3d7dfd632f9b60cfce069b4da517e6b1a1c3f613 (patch) | |
tree | 02ec1e93d286d7c49dce90a4294f8ddc1edb3af4 /arch/powerpc/include/asm/book3s/64/kup-radix.h | |
parent | 5cd623333e7cf4e3a334c70529268b65f2a6c2c7 (diff) | |
download | linux-3d7dfd632f9b60cfce069b4da517e6b1a1c3f613.tar.xz |
powerpc: Implement user_access_save() and user_access_restore()
Implement user_access_save() and user_access_restore()
On 8xx and radix:
- On save, get the value of the associated special register then
prevent user access.
- On restore, set back the saved value to the associated special
register.
On book3s/32:
- On save, get the value stored in current->thread.kuap and prevent
user access.
- On restore, regenerate address range from the stored value and
reopen read/write access for that range.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/54f2f74938006b33c55a416674807b42ef222068.1579866752.git.christophe.leroy@c-s.fr
Diffstat (limited to 'arch/powerpc/include/asm/book3s/64/kup-radix.h')
-rw-r--r-- | arch/powerpc/include/asm/book3s/64/kup-radix.h | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/book3s/64/kup-radix.h b/arch/powerpc/include/asm/book3s/64/kup-radix.h index a0263e94df33..90dd3a3fc8c7 100644 --- a/arch/powerpc/include/asm/book3s/64/kup-radix.h +++ b/arch/powerpc/include/asm/book3s/64/kup-radix.h @@ -63,6 +63,14 @@ * because that would require an expensive read/modify write of the AMR. */ +static inline unsigned long get_kuap(void) +{ + if (!early_mmu_has_feature(MMU_FTR_RADIX_KUAP)) + return 0; + + return mfspr(SPRN_AMR); +} + static inline void set_kuap(unsigned long value) { if (!early_mmu_has_feature(MMU_FTR_RADIX_KUAP)) @@ -98,6 +106,20 @@ static inline void prevent_user_access(void __user *to, const void __user *from, set_kuap(AMR_KUAP_BLOCKED); } +static inline unsigned long prevent_user_access_return(void) +{ + unsigned long flags = get_kuap(); + + set_kuap(AMR_KUAP_BLOCKED); + + return flags; +} + +static inline void restore_user_access(unsigned long flags) +{ + set_kuap(flags); +} + static inline bool bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write) { |