linux.git/arch/powerpc/kernel/entry_32.S, branch v5.12

powerpc/32: Handle bookE debugging in C in syscall entry/exit

2021-02-11T12:35:12+00:00

The handling of SPRN_DBCR0 and other registers can easily
be done in C instead of ASM.

For that, create booke_load_dbcr0() and booke_restore_dbcr0().

Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/1a7515f9258b27a9177de88491a8bb79b255ceb7.1612898425.git.christophe.leroy@csgroup.eu

powerpc/32: Remove the counter in global_dbcr0

2021-02-11T12:35:12+00:00

global_dbcr0 has two parts, 4 bytes to save/restore the
value of SPRN_DBCR0, and 4 bytes that are incremented/decremented
everytime something is saving/loading the above value.

This counter is only incremented/decremented, its value is never
used and never read.

Remove the counter and devide the size of global_dbcr0 by 2.

Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/7e381dc58b3f583556cfab37ba5d813bfd5cce1e.1612796617.git.christophe.leroy@csgroup.eu

powerpc/32: Remove verification of MSR_PR on syscall in the ASM entry

2021-02-11T12:35:11+00:00

system_call_exception() checks MSR_PR and BUGs if a syscall
is issued from kernel mode.

No need to handle it anymore from the ASM entry code.

null_syscall reduction 2 cycles (348 => 346 cycles)

Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/1eddb42cb12092b1e3d72608d182c365db3da41d.1612796617.git.christophe.leroy@csgroup.eu

powerpc/syscall: implement system call entry/exit logic in C for PPC32

2021-02-11T12:35:11+00:00

That's port of PPC64 syscall entry/exit logic in C to PPC32.

Performancewise on 8xx:
Before : 304 cycles on null_syscall
After  : 348 cycles on null_syscall

Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/a93b08e1275e9d1f0b1c39043d1b827586b2b401.1612796617.git.christophe.leroy@csgroup.eu

powerpc/32: Always save non volatile GPRs at syscall entry

2021-02-11T12:35:11+00:00

In preparation for porting syscall entry/exit to C, inconditionally
save non volatile general purpose registers.

Commit 965dd3ad3076 ("powerpc/64/syscall: Remove non-volatile GPR save
optimisation") provides detailed explanation.

This increases the number of cycles by 24 cycles on 8xx with
null_syscall benchmark (280 => 304 cycles)

Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/21c08162b83655195fe9ead78ff2cfd28508d023.1612796617.git.christophe.leroy@csgroup.eu

powerpc/32s: Add missing call to kuep_lock on syscall entry

2021-02-11T12:35:08+00:00

Userspace Execution protection and fast syscall entry were implemented
independently from each other and were both merged in kernel 5.2,
leading to syscall entry missing userspace execution protection.

On syscall entry, execution of user space memory must be
locked in the same way as on exception entry.

Fixes: b86fb88855ea ("powerpc/32: implement fast entry for syscalls on non BOOKE")
Cc: stable@vger.kernel.org
Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/c65e105b63aaf74f91a14f845bc77192350b84a6.1612796617.git.christophe.leroy@csgroup.eu

powerpc: bad_page_fault get registers from regs

2021-02-08T13:02:09+00:00

Similar to the previous patch this makes interrupt handler function
types more regular so they can be wrapped with the next patch.

Signed-off-by: Nicholas Piggin 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20210130130852.2952424-12-npiggin@gmail.com

powerpc/32: transfer can avoid saving r4/r5 over trace call

2021-02-08T13:02:09+00:00

Now that handlers get all registers from pt_regs, r4 and r5 are no
longer live here and may be clobbered.

Signed-off-by: Nicholas Piggin 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20210130130852.2952424-11-npiggin@gmail.com

powerpc/32s: move DABR match out of handle_page_fault

2021-02-08T13:02:08+00:00

handle_page_fault() has some code dedicated to book3s/32 to
call do_break() when the DSI is a DABR match.

On other platforms, do_break() is handled separately.

Do the same for book3s/32, do it earlier in the process of DSI.

This change also avoid doing the test on ISI.

Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20210130130852.2952424-4-npiggin@gmail.com

powerpc/fault: Perform exception fixup in do_page_fault()

2020-12-09T12:48:14+00:00

Exception fixup doesn't require the heady full regs saving,
do it from do_page_fault() directly.

For that, split bad_page_fault() in two parts.

As bad_page_fault() can also be called from other places than
handle_page_fault(), it will still perform exception fixup and
fallback on __bad_page_fault().

handle_page_fault() directly calls __bad_page_fault() as the
exception fixup will now be done by do_page_fault()

Signed-off-by: Christophe Leroy 
Reviewed-by: Nicholas Piggin 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/bd07d6fef9237614cd6d318d8f19faeeadaa816b.1607491748.git.christophe.leroy@csgroup.eu