linux/arch/arm64/kernel/probes
Alexandru Elisei 8d56e5c5a9 arm64: Treat ESR_ELx as a 64-bit register
In the initial release of the ARM Architecture Reference Manual for
ARMv8-A, the ESR_ELx registers were defined as 32-bit registers. This
changed in 2018 with version D.a (ARM DDI 0487D.a) of the architecture,
when they became 64-bit registers, with bits [63:32] defined as RES0. In
version G.a, a new field was added to ESR_ELx, ISS2, which covers bits
[36:32].  This field is used when the Armv8.7 extension FEAT_LS64 is
implemented.

As a result of the evolution of the register width, Linux stores it as
both a 64-bit value and a 32-bit value, which hasn't affected correctness
so far as Linux only uses the lower 32 bits of the register.

Make the register type consistent and always treat it as 64-bit wide. The
register is redefined as an "unsigned long", which is an unsigned
double-word (64-bit quantity) for the LP64 machine (aapcs64 [1], Table 1,
page 14). The type was chosen because "unsigned int" is the most frequent
type for ESR_ELx and because FAR_ELx, which is used together with ESR_ELx
in exception handling, is also declared as "unsigned long". The 64-bit type
also makes adding support for architectural features that use fields above
bit 31 easier in the future.

The KVM hypervisor will receive a similar update in a subsequent patch.

[1] https://github.com/ARM-software/abi-aa/releases/download/2021Q3/aapcs64.pdf

Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220425114444.368693-4-alexandru.elisei@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2022-04-29 19:26:27 +01:00
..
decode-insn.c arm64: kprobe: clarify the comment of steppable hint instructions 2020-09-14 12:07:03 +01:00
decode-insn.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 174 2019-05-30 11:26:41 -07:00
kprobes_trampoline.S arm64: kprobes: Make a frame pointer on __kretprobe_trampoline 2021-10-22 12:16:53 -04:00
kprobes.c arm64: Treat ESR_ELx as a 64-bit register 2022-04-29 19:26:27 +01:00
Makefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
simulate-insn.c arm64: Move aarch32 condition check functions 2021-05-27 17:38:07 +01:00
simulate-insn.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 174 2019-05-30 11:26:41 -07:00
uprobes.c arm64: Treat ESR_ELx as a 64-bit register 2022-04-29 19:26:27 +01:00