This commit comes at the tail end of a greater effort to remove the
empty elements at the end of the ctl_table arrays (sentinels) which
will reduce the overall build time size of the kernel and run time
memory bloat by ~64 bytes per sentinel (further information Link :
https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/)

Removed the sentinel as well as the explicit size from ctl_isa_vars. The
size is redundant as the initialization sets it. Changed
insn_emulation->sysctl from a 2 element array of struct ctl_table to a
simple struct. This has no consequence for the sysctl registration as it
is forwarded as a pointer. Removed sentinel from sve_defatul_vl_table,
sme_default_vl_table, tagged_addr_sysctl_table and
armv8_pmu_sysctl_table.

This removal is safe because register_sysctl_sz and register_sysctl use
the array size in addition to checking for the sentinel.

Signed-off-by: Joel Granados <j.granados@samsung.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>

This commit adds table_size to register_sysctl in preparation for the
removal of the sentinel elements in the ctl_table arrays (last empty
markers). And though we do *not* remove any sentinels in this commit, we
set things up by either passing the table_size explicitly or using
ARRAY_SIZE on the ctl_table arrays.

We replace the register_syctl function with a macro that will add the
ARRAY_SIZE to the new register_sysctl_sz function. In this way the
callers that are already using an array of ctl_table structs do not
change. For the callers that pass a ctl_table array pointer, we pass the
table_size to register_sysctl_sz instead of the macro.

Signed-off-by: Joel Granados <j.granados@samsung.com>
Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>

Pointer variables of void * type do not require type cast.

Signed-off-by: Yu Zhe <yuzhe@nfschina.com>
Link: https://lore.kernel.org/r/20230303025047.19717-1-yuzhe@nfschina.com
Signed-off-by: Will Deacon <will@kernel.org>

If CONFIG_SWP_EMULATION is not set and
CONFIG_CP15_BARRIER_EMULATION is not set,
aarch64-linux-gnu complained about unused-function :

arch/arm64/kernel/armv8_deprecated.c:67:21: error: ‘aarch32_check_condition’ defined but not used [-Werror=unused-function]
 static unsigned int aarch32_check_condition(u32 opcode, u32 psr)
                     ^~~~~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors

To fix this warning, modify aarch32_check_condition() with __maybe_unused.

Fixes: 0c5f416219da ("arm64: armv8_deprecated: move aarch32 helper earlier")
Signed-off-by: Ren Zhijie <renzhijie2@huawei.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20221124022429.19024-1-renzhijie2@huawei.com
Signed-off-by: Will Deacon <will@kernel.org>

Support for deprecated instructions can be enabled or disabled at
runtime. To handle this, the code in armv8_deprecated.c registers and
unregisters undef_hooks, and makes cross CPU calls to configure HW
support. This is rather complicated, and the synchronization required to
make this safe ends up serializing the handling of instructions which
have been trapped.

This patch simplifies the deprecated instruction handling by removing
the dynamic registration and unregistration, and changing the trap
handling code to determine whether a handler should be invoked. This
removes the need for dynamic list management, and simplifies the locking
requirements, making it possible to handle trapped instructions entirely
in parallel.

Where changing the emulation state requires a cross-call, this is
serialized by locally disabling interrupts, ensuring that the CPU is not
left in an inconsistent state.

To simplify sysctl management, each insn_emulation is given a separate
sysctl table, permitting these to be registered separately. The core
sysctl code will iterate over all of these when walking sysfs.

I've tested this with userspace programs which use each of the
deprecated instructions, and I've concurrently modified the support
level for each of the features back-and-forth between HW and emulated to
check that there are no spurious SIGILLs sent to userspace when the
support level is changed.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Joey Gouly <joey.gouly@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20221019144123.612388-10-mark.rutland@arm.com
Signed-off-by: Will Deacon <will@kernel.org>

Subsequent patches will rework the logic in armv8_deprecated.c.

In preparation for subsequent changes, this patch moves some shared logic
earlier in the file. This will make subsequent diffs simpler and easier to
read.

At the same time, drop the `__kprobes` annotation from
aarch32_check_condition(), as this is only used for traps from compat
userspace, and has no risk of recursion within kprobes. As this is the
last kprobes annotation in armve8_deprecated.c, we no longer need to
include <asm/kprobes.h>.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Joey Gouly <joey.gouly@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20221019144123.612388-9-mark.rutland@arm.com
Signed-off-by: Will Deacon <will@kernel.org>

Subsequent patches will rework the logic in armv8_deprecated.c.

In preparation for subsequent changes, this patch moves the emulation
logic earlier in the file, and moves the infrastructure later in the
file. This will make subsequent diffs simpler and easier to read.

This is purely a move. There should be no functional change as a result
of this patch.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Joey Gouly <joey.gouly@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20221019144123.612388-8-mark.rutland@arm.com
Signed-off-by: Will Deacon <will@kernel.org>

The code for emulating deprecated instructions has two related
structures: struct insn_emulation_ops and struct insn_emulation, where
each struct insn_emulation_ops is associated 1-1 with a struct
insn_emulation.

It would be simpler to combine the two into a single structure, removing
the need for (unconditional) dynamic allocation at boot time, and
simplifying some runtime pointer chasing.

This patch merges the two structures together.

There should be no functional change as a result of this patch.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Joey Gouly <joey.gouly@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20221019144123.612388-7-mark.rutland@arm.com
Signed-off-by: Will Deacon <will@kernel.org>

emulation_proc_handler() changes table->data for proc_dointvec_minmax
and can generate the following Oops if called concurrently with itself:

 | Unable to handle kernel NULL pointer dereference at virtual address 0000000000000010
 | Internal error: Oops: 96000006 [#1] SMP
 | Call trace:
 | update_insn_emulation_mode+0xc0/0x148
 | emulation_proc_handler+0x64/0xb8
 | proc_sys_call_handler+0x9c/0xf8
 | proc_sys_write+0x18/0x20
 | __vfs_write+0x20/0x48
 | vfs_write+0xe4/0x1d0
 | ksys_write+0x70/0xf8
 | __arm64_sys_write+0x20/0x28
 | el0_svc_common.constprop.0+0x7c/0x1c0
 | el0_svc_handler+0x2c/0xa0
 | el0_svc+0x8/0x200

To fix this issue, keep the table->data as &insn->current_mode and
use container_of() to retrieve the insn pointer. Another mutex is
used to protect against the current_mode update but not for retrieving
insn_emulation as table->data is no longer changing.

Co-developed-by: hewenliang <hewenliang4@huawei.com>
Signed-off-by: hewenliang <hewenliang4@huawei.com>
Signed-off-by: Haibin Zhang <haibinzhang@tencent.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20220128090324.2727688-1-hewenliang4@huawei.com
Link: https://lore.kernel.org/r/9A004C03-250B-46C5-BF39-782D7551B00E@tencent.com
Signed-off-by: Will Deacon <will@kernel.org>

For inline assembly, we place exception fixups out-of-line in the
`.fixup` section such that these are out of the way of the fast path.
This has a few drawbacks:

* Since the fixup code is anonymous, backtraces will symbolize fixups as
  offsets from the nearest prior symbol, currently
  `__entry_tramp_text_end`. This is confusing, and painful to debug
  without access to the relevant vmlinux.

* Since the exception handler adjusts the PC to execute the fixup, and
  the fixup uses a direct branch back into the function it fixes,
  backtraces of fixups miss the original function. This is confusing,
  and violates requirements for RELIABLE_STACKTRACE (and therefore
  LIVEPATCH).

* Inline assembly and associated fixups are generated from templates,
  and we have many copies of logically identical fixups which only
  differ in which specific registers are written to and which address is
  branched to at the end of the fixup. This is potentially wasteful of
  I-cache resources, and makes it hard to add additional logic to fixups
  without significant bloat.

This patch address all three concerns for inline uaccess fixups by
adding a dedicated exception handler which updates registers in
exception context and subsequent returns back into the function which
faulted, removing the need for fixups specialized to each faulting
instruction.

Other than backtracing, there should be no functional change as a result
of this patch.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20211019160219.5202-12-mark.rutland@arm.com
Signed-off-by: Will Deacon <will@kernel.org>