linux.git/arch/powerpc/kernel/entry_32.S, branch v5.15

powerpc/32: indirect function call use bctrl rather than blrl in ret_from_kernel_thread

2021-08-25T03:35:47+00:00

Copied from commit 89bbe4c798bc ("powerpc/64: indirect function call
use bctrl rather than blrl in ret_from_kernel_thread")

blrl is not recommended to use as an indirect function call, as it may
corrupt the link stack predictor.

This is not a performance critical path but this should be fixed for
consistency.

Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/91b1d242525307ceceec7ef6e832bfbacdd4501b.1629436472.git.christophe.leroy@csgroup.eu

powerpc/32: Reduce code duplication of system call entry

2021-06-24T14:07:10+00:00

booke and non booke do pretty similar things in SYSCALL_ENTRY macro
just before calling jumping to transfer_to_syscall().

Do them in transfer_to_syscall() instead.

Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/552e27fa09394a6bc70585fcdfa237f99a5d1267.1622818435.git.christophe.leroy@csgroup.eu

powerpc: Don't handle ALTIVEC/SPE in ASM in _switch(). Do it in C.

2021-06-15T14:16:47+00:00

_switch() saves and restores ALTIVEC and SPE status.
For altivec this is redundant with what __switch_to() does with
save_sprs() and restore_sprs() and giveup_all() before
calling _switch().

Add support for SPI in save_sprs() and restore_sprs() and
remove things from _switch().

Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/8ab21fd93d6e0047aa71e6509e5e312f14b2991b.1620998075.git.christophe.leroy@csgroup.eu

powerpc/32: Manage KUAP in C

2021-03-29T02:22:11+00:00

Move all KUAP management in C.

Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/199365ddb58d579daf724815f2d0acb91cc49d19.1615552867.git.christophe.leroy@csgroup.eu

powerpc/32s: Move KUEP locking/unlocking in C

2021-03-29T02:22:10+00:00

This can be done in C, do it.

Unrolling the loop gains approx. 15% performance.

From now on, prepare_transfer_to_handler() is only for
interrupts from kernel.

Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/4eadd873927e9a73c3d1dfe2f9497353465514cf.1615552867.git.christophe.leroy@csgroup.eu

powerpc/32: Only use prepare_transfer_to_handler function on book3s/32 and e500

2021-03-29T02:22:10+00:00

Only book3s/32 and e500 have significative work to do in
prepare_transfer_to_handler.

Other 32 bit have nothing to do at all.

Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/b5e29ca0e557c11340415a13fe8b107189d315e1.1615552867.git.christophe.leroy@csgroup.eu

powerpc/32: Return directly from power_save_ppc32_restore()

2021-03-29T02:22:10+00:00

transfer_to_handler_cont: is now just a blr.

Directly perform blr in power_save_ppc32_restore().

Also remove useless setting of r11 in e500 version of
power_save_ppc32_restore().

Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/e337506e08a4df95b11d2290104b92f0dcdb5548.1615552867.git.christophe.leroy@csgroup.eu

powerpc/32: Save remaining registers in exception prolog

2021-03-29T02:22:10+00:00

Save non volatile registers, XER, CTR, MSR and NIP in exception prolog.

Also assign proper value to r2 and r3 there.

For now, recalculate thread pointer in prepare_transfer_to_handler.
It will disappear once KUAP is ported to C.

And remove the comment which is now completely wrong.

Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/56f0cde9dd0362edf2ddba4d887552013eee7329.1615552867.git.christophe.leroy@csgroup.eu

powerpc/32: Dismantle EXC_XFER_STD/LITE/TEMPLATE

2021-03-29T02:22:09+00:00

In order to get more control in exception prolog, dismantle
all non standard exception macros, finishing with EXC_XFER_STD
and EXC_XFER_LITE and EXC_XFER_TEMPLATE.

Also remove transfer_to_handler_full and ret_from_except and
ret_from_except_full as they are not used anymore.

Last parameter of EXCEPTION() is now ignored, will be removed
in a later patch to avoid too much churn.

Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/ca5795d04a220586b7037dbbbe6951dfa9e768eb.1615552867.git.christophe.leroy@csgroup.eu

powerpc/32: Only restore non volatile registers when required

2021-03-29T02:22:09+00:00

Until now, non volatile registers were restored everytime they
were saved, ie using EXC_XFER_STD meant saving and restoring
them while EXC_XFER_LITE meant neither saving not restoring them.

Now that they are always saved, EXC_XFER_STD means to restore
them and EXC_XFER_LITE means to not restore them.

Most of the users of EXC_XFER_STD only need to retrieve the
non volatile registers. For them there is no need to restore
the non volatile registers as they have not been modified.

Only very few exceptions require non volatile registers restore.

Opencode the few places which require saving of non volatile
registers.

Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/d1cb12d8023cc6afc1f07150565571373c04945c.1615552867.git.christophe.leroy@csgroup.eu