linux-toradex.git/arch/arm/vfp, branch v6.5

Merge tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm

2023-06-27T00:07:53+00:00

Pull ARM updates from Russell King:

 - lots of build cleanups from Arnd spread throughout the arch/arm tree

 - replace strlcpy() with the preferred strscpy()

 - use sign_extend32() in the module linker

 - drop handle_irq() machine descriptor method

* tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm:
  ARM: 9315/1: fiq: include asm/mach/irq.h for prototypes
  ARM: 9314/1: tcm: move tcm_init() prototype to asm/tcm.h
  ARM: 9313/1: vdso: add missing prototypes
  ARM: 9312/1: vfp: include asm/neon.h in vfpmodule.c
  ARM: 9311/1: decompressor: move function prototypes to misc.h
  ARM: 9310/1: xip-kernel: add __inflate_kernel_data prototype
  ARM: 9309/1: add missing syscall prototypes
  ARM: 9308/1: move setup functions to header
  ARM: 9307/1: nommu: include asm/idmap.h
  ARM: 9306/1: cacheflush: avoid __flush_anon_page() missing-prototype warning
  ARM: 9305/1: add clear/copy_user_highpage declarations
  ARM: 9304/1: add prototype for function called only from asm
  ARM: 9303/1: kprobes: avoid missing-declaration warnings
  ARM: 9302/1: traps: hide unused functions on NOMMU
  ARM: 9301/1: dma-mapping: hide unused dma_contiguous_early_fixup function
  ARM: 9300/1: Replace all non-returning strlcpy with strscpy
  ARM: 9299/1: module: use sign_extend32() to extend the signedness
  ARM: 9298/1: Drop custom mdesc->handle_irq()

ARM: 9312/1: vfp: include asm/neon.h in vfpmodule.c

2023-06-19T08:35:58+00:00

Two functions defined here need the declaration in a header
to avoid W=1 warnings:

arch/arm/vfp/vfpmodule.c:735:6: error: no previous prototype for 'kernel_neon_begin' [-Werror=missing-prototypes]
arch/arm/vfp/vfpmodule.c:768:6: error: no previous prototype for 'kernel_neon_end' [-Werror=missing-prototypes]

Reviewed-by: Kees Cook 
Signed-off-by: Arnd Bergmann 
Signed-off-by: Russell King (Oracle)

ARM: 9297/1: vfp: avoid unbalanced stack on 'success' return path

2023-05-10T09:50:25+00:00

Commit c76c6c4ecbec0deb5 ("ARM: 9294/2: vfp: Fix broken softirq handling
with instrumentation enabled") updated the VFP exception entry logic to
go via a C function, so that we get the compiler's version of
local_bh_disable(), which may be instrumented, and isn't generally
callable from assembler.

However, this assumes that passing an alternative 'success' return
address works in C as it does in asm, and this is only the case if the C
calls in question are tail calls, as otherwise, the stack will need some
unwinding as well.

I have already sent patches to the list that replace most of the asm
logic with C code, and so it is preferable to have a minimal fix that
addresses the issue and can be backported along with the commit that it

fixes to v6.3 from v6.4. Hopefully, we can land the C conversion for v6.5.

So instead of passing the 'success' return address as a function
argument, pass the stack address from where to pop it so that both LR
and SP have the expected value.

Fixes: c76c6c4ecbec0deb5 ("ARM: 9294/2: vfp: Fix broken softirq handling with ...")
Reported-by: syzbot+d4b00edc2d0c910d4bf4@syzkaller.appspotmail.com
Tested-by: syzbot+d4b00edc2d0c910d4bf4@syzkaller.appspotmail.com
Reviewed-by: Linus Walleij 
Tested-by: Andrew Lunn 
Signed-off-by: Ard Biesheuvel 
Tested-by: Andre Przywara 
Signed-off-by: Russell King (Oracle)

ARM: 9294/2: vfp: Fix broken softirq handling with instrumentation enabled

2023-04-12T09:04:56+00:00

Commit 62b95a7b44d1 ("ARM: 9282/1: vfp: Manipulate task VFP state with
softirqs disabled") replaced the en/disable preemption calls inside the
VFP state handling code with en/disabling of soft IRQs, which is
necessary to allow kernel use of the VFP/SIMD unit when handling a soft
IRQ.

Unfortunately, when lockdep is enabled (or other instrumentation that
enables TRACE_IRQFLAGS), the disable path implemented in asm fails to
perform the lockdep and RCU related bookkeeping, resulting in spurious
warnings and other badness.

Set let's rework the VFP entry code a little bit so we can make the
local_bh_disable() call from C, with all the instrumentations that
happen to have been configured. Calling local_bh_enable() can be done
from asm, as it is a simple wrapper around __local_bh_enable_ip(), which
is always a callable function.

Link: https://lore.kernel.org/all/ZBBYCSZUJOWBg1s8@localhost.localdomain/

Fixes: 62b95a7b44d1 ("ARM: 9282/1: vfp: Manipulate task VFP state with softirqs disabled")
Signed-off-by: Ard Biesheuvel 
Reviewed-by: Linus Walleij 
Tested-by: Guenter Roeck 
Signed-off-by: Russell King (Oracle)

ARM: 9293/1: vfp: Pass successful return address via register R3

2023-04-11T10:07:10+00:00

In preparation for reimplementing the do_vfp()->vfp_support_entry()
handover in C code, switch to using R3 to pass the 'success' return
address, rather than R9, as it cannot be used for parameter passing.

Signed-off-by: Ard Biesheuvel 
Reviewed-by: Linus Walleij 
Tested-by: Guenter Roeck 
Signed-off-by: Russell King (Oracle)

ARM: 9292/1: vfp: Pass thread_info pointer to vfp_support_entry

2023-04-11T10:07:08+00:00

Instead of dereferencing thread_info in do_vfp, pass the thread_info
pointer to vfp_support_entry via R1. That way, we only use a single
caller save register, which makes it easier to convert do_vfp to C code
in a subsequent patch.

Note that, unlike the CPU number, which can change due to preemption,
passing the thread_info pointer can safely be done with preemption
enabled.

Signed-off-by: Ard Biesheuvel 
Reviewed-by: Linus Walleij 
Tested-by: Guenter Roeck 
Signed-off-by: Russell King (Oracle)

ARM: 9283/1: permit non-nested kernel mode NEON in softirq context

2023-01-11T16:21:21+00:00

We currently only permit kernel mode NEON in process context, to avoid
the need to preserve/restore the NEON register file when taking an
exception while running in the kernel.

Like we did on arm64, we can relax this restriction substantially, by
permitting kernel mode NEON from softirq context, while ensuring that
softirq processing is disabled when the NEON is being used in task
context. This guarantees that only NEON context belonging to user space
needs to be preserved and restored, which is already taken care of.

This is especially relevant for network encryption, where incoming
frames are typically handled in softirq context, and deferring software
decryption to a kernel thread or falling back to C code are both
undesirable from a performance PoV.

Tested-by: Martin Willi 
Reviewed-by: Linus Walleij 
Signed-off-by: Ard Biesheuvel 
Signed-off-by: Russell King (Oracle)

ARM: 9282/1: vfp: Manipulate task VFP state with softirqs disabled

2023-01-11T16:21:20+00:00

In a subsequent patch, we will relax the kernel mode NEON policy, and
permit kernel mode NEON to be used not only from task context, as is
permitted today, but also from softirq context.

Given that softirqs may trigger over the back of any IRQ unless they are
explicitly disabled, we need to address the resulting races in the VFP
state handling, by disabling softirq processing in two distinct but
related cases:
- kernel mode NEON will leave the FPU disabled after it completes, so
  any kernel code sequence that enables the FPU and subsequently accesses
  its registers needs to disable softirqs until it completes;
- kernel_neon_begin() will preserve the userland VFP state in memory,
  and if it interrupts the ordinary VFP state preserve sequence, the
  latter will resume execution with the VFP registers corrupted, and
  happily continue saving them to memory.

Given that disabling softirqs also disables preemption, we can replace
the existing preempt_disable/enable occurrences in the VFP state
handling asm code with new macros that dis/enable softirqs instead.
In the VFP state handling C code, add local_bh_disable/enable() calls
in those places where the VFP state is preserved.

One thing to keep in mind is that, once we allow NEON use in softirq
context, the result of any such interruption is that the FPEXC_EN bit in
the FPEXC register will be cleared, and vfp_current_hw_state[cpu] will
be NULL. This means that any sequence that [conditionally] clears
FPEXC_EN and/or sets vfp_current_hw_state[cpu] to NULL does not need to
run with softirqs disabled, as the result will be the same. Furthermore,
the handling of THREAD_NOTIFY_SWITCH is guaranteed to run with IRQs
disabled, and so it does not need protection from softirq interruptions
either.

Tested-by: Martin Willi 
Reviewed-by: Linus Walleij 
Signed-off-by: Ard Biesheuvel 
Signed-off-by: Russell King (Oracle)

ARM: 9272/1: vfp: Add hwcap for FEAT_AA32I8MM

2022-11-28T11:57:34+00:00

Int8 matrix multiplication (FEAT_AA32I8MM) is a feature present in AArch32 state for Armv8 and is represented by ISAR6.I8MM identification register.

This feature denotes the presence of VSMMLA, VSUDOT, VUMMLA, VUSMMLA and
VUSDOT instructions and hence adding a hwcap will enable the userspace
to check it before trying to use those instructions.

Reviewed-by: Linus Walleij 
Signed-off-by: Amit Daniel Kachhap 
Signed-off-by: Russell King (Oracle)

ARM: 9271/1: vfp: Add hwcap for FEAT_AA32BF16

2022-11-28T11:57:33+00:00

Advanced SIMD BFloat16 (FEAT_AA32BF16) is a feature present in AArch32
state for Armv8 and is represented by ISAR6.BF16 identification
register.

This feature denotes the presence of VCVT, VCVTB, VCVTT, VDOT, VFMAB,
VFMAT and VMMLA instructions and hence adding a hwcap will enable the
userspace to check it before trying to use those instructions.

Reviewed-by: Linus Walleij 
Signed-off-by: Amit Daniel Kachhap 
Signed-off-by: Russell King (Oracle)