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| author |   Christophe Leroy <christophe.leroy@csgroup.eu> | 2021-10-19 09:29:18 +0200 |
|---|---|---|
| committer |   Michael Ellerman <mpe@ellerman.id.au> | 2021-12-09 22:41:17 +1100 |
| commit | 70428da94c7ad692d306747a04117543827292a7 (patch) | |
| tree | a9c27bfdbaa5b4b79a93564f80ac31165f4ff560 /arch/powerpc/kernel/entry_32.S | |
| parent | powerpc/32s: Do kuep_lock() and kuep_unlock() in assembly (diff) | |
| download | linux-dev-70428da94c7ad692d306747a04117543827292a7.tar.xz linux-dev-70428da94c7ad692d306747a04117543827292a7.zip | |
powerpc/32s: Save content of sr0 to avoid 'mfsr'
Calling 'mfsr' to get the content of segment registers is heavy,
in addition it requires clearing of the 'reserved' bits.
In order to avoid this operation, save it in mm context and in
thread struct.
The saved sr0 is the one used by kernel, this means that on
locking entry it can be used as is.
For unlocking, the only thing to do is to clear SR_NX.
This improves null_syscall selftest by 12 cycles, ie 4%.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/b02baf2ed8f09bad910dfaeeb7353b2ae6830525.1634627931.git.christophe.leroy@csgroup.eu
Diffstat (limited to 'arch/powerpc/kernel/entry_32.S')
| -rw-r--r-- | arch/powerpc/kernel/entry_32.S | 8 |
1 files changed, 3 insertions, 5 deletions
diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S index 0756829b2f7f..035bf4f3eb5d 100644 --- a/arch/powerpc/kernel/entry_32.S +++ b/arch/powerpc/kernel/entry_32.S @@ -76,15 +76,13 @@ _ASM_NOKPROBE_SYMBOL(prepare_transfer_to_handler) #if defined(CONFIG_PPC_KUEP) && defined(CONFIG_PPC_BOOK3S_32) .globl __kuep_lock __kuep_lock: - mfsr r9,0 - rlwinm r9,r9,0,8,3 - oris r9,r9,SR_NX@h + lwz r9, THREAD+THSR0(r2) update_user_segments_by_4 r9, r10, r11, r12 blr __kuep_unlock: - mfsr r9,0 - rlwinm r9,r9,0,8,2 + lwz r9, THREAD+THSR0(r2) + rlwinm r9,r9,0,~SR_NX update_user_segments_by_4 r9, r10, r11, r12 blr |