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| author | Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> | 2020-11-27 05:44:12 +0100 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2020-12-03 15:01:25 +0100 |
| commit | 8e560921b58cbc18e192f0ac273d307a37a144f9 (patch) | |
| tree | c31889658923af6daebd988632f9d19a738b98cd /arch/powerpc/kernel/entry_64.S | |
| parent | powerpc/exec: Set thread.regs early during exec (diff) | |
| download | linux-8e560921b58cbc18e192f0ac273d307a37a144f9.tar.xz linux-8e560921b58cbc18e192f0ac273d307a37a144f9.zip | |
powerpc/book3s64/pkeys: Store/restore userspace AMR/IAMR correctly on entry and exit from kernel
This prepare kernel to operate with a different value than userspace AMR/IAMR.
For this, AMR/IAMR need to be saved and restored on entry and return from the
kernel.
With KUAP we modify kernel AMR when accessing user address from the kernel
via copy_to/from_user interfaces. We don't need to modify IAMR value in
similar fashion.
If MMU_FTR_PKEY is enabled we need to save AMR/IAMR in pt_regs on entering
kernel from userspace. If not we can assume that AMR/IAMR is not modified
from userspace.
We need to save AMR if we have MMU_FTR_BOOK3S_KUAP feature enabled and we are
interrupted within kernel. This is required so that if we get interrupted
within copy_to/from_user we continue with the right AMR value.
If we hae MMU_FTR_BOOK3S_KUEP enabled we need to restore IAMR on
return to userspace beause kernel will be running with a different
IAMR value.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Reviewed-by: Sandipan Das <sandipan@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201127044424.40686-11-aneesh.kumar@linux.ibm.com
Diffstat (limited to 'arch/powerpc/kernel/entry_64.S')
| -rw-r--r-- | arch/powerpc/kernel/entry_64.S | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S index 2f3846192ec7..da23c397ceb2 100644 --- a/arch/powerpc/kernel/entry_64.S +++ b/arch/powerpc/kernel/entry_64.S @@ -653,8 +653,8 @@ _ASM_NOKPROBE_SYMBOL(fast_interrupt_return) kuap_check_amr r3, r4 ld r5,_MSR(r1) andi. r0,r5,MSR_PR - bne .Lfast_user_interrupt_return - kuap_restore_amr r3, r4 + bne .Lfast_user_interrupt_return_amr + kuap_kernel_restore r3, r4 andi. r0,r5,MSR_RI li r3,0 /* 0 return value, no EMULATE_STACK_STORE */ bne+ .Lfast_kernel_interrupt_return @@ -674,6 +674,8 @@ _ASM_NOKPROBE_SYMBOL(interrupt_return) cmpdi r3,0 bne- .Lrestore_nvgprs +.Lfast_user_interrupt_return_amr: + kuap_user_restore r3 .Lfast_user_interrupt_return: ld r11,_NIP(r1) ld r12,_MSR(r1) |