Subsequent patches will add specialized handlers for fixups, in addition
to the simple PC fixup and BPF handlers we have today. In preparation,
this patch adds a new `type` field to struct exception_table_entry, and
uses this to distinguish the fixup and BPF cases. A `data` field is also
added so that subsequent patches can associate data specific to each
exception site (e.g. register numbers).
Handlers are named ex_handler_*() for consistency, following the exmaple
of x86. At the same time, get_ex_fixup() is split out into a helper so
that it can be used by other ex_handler_*() functions ins subsequent
patches.
This patch will increase the size of the exception tables, which will be
remedied by subsequent patches removing redundant fixup code. There
should be no functional change as a result of this patch.
Since each entry is now 12 bytes in size, we must reduce the alignment
of each entry from `.align 3` (i.e. 8 bytes) to `.align 2` (i.e. 4
bytes), which is the natrual alignment of the `insn` and `fixup` fields.
The current 8-byte alignment is a holdover from when the `insn` and
`fixup` fields was 8 bytes, and while not harmful has not been necessary
since commit:
6c94f27ac8 ("arm64: switch to relative exception tables")
Similarly, RO_EXCEPTION_TABLE_ALIGN is dropped to 4 bytes.
Concurrently with this patch, x86's exception table entry format is
being updated (similarly to a 12-byte format, with 32-bytes of absolute
data). Once both have been merged it should be possible to unify the
sorttable logic for the two.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: James Morse <james.morse@arm.com>
Cc: Jean-Philippe Brucker <jean-philippe@linaro.org>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20211019160219.5202-11-mark.rutland@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
Enable BUILDTIME_TABLE_SORT to sort the exception table at build time
rather than during boot.
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
This is a s390 port of commit 548acf1923 ("x86/mm: Expand the
exception table logic to allow new handling options"), which is needed
for implementing BPF_PROBE_MEM on s390.
The new handler field is made 64-bit in order to allow pointing from
dynamically allocated entries to handlers in kernel text. Unlike on x86,
NULL is used instead of ex_handler_default. This is because exception
tables are used by boot/text_dma.S, and it would be a pain to preserve
ex_handler_default.
The new infrastructure is ignored in early_pgm_check_handler, since
there is no pt_regs.
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
