linux/arch
Heiko Stuebner 1771c8c9e6
riscv: remove usage of function-pointers from cpufeatures and t-head errata
Having a list of alternatives to check with a per-entry function pointer
to a check function is nice style-wise. But in case of early-alternatives
it can clash with the non-relocated kernel and the function pointer in
the list pointing to a completely wrong location.

This isn't an issue with one or two list entries, as in that case the
compiler seems to unroll the loop and even usage of the list structure
and then only does relative jumps into the check functions based on this.

When adding a third entry to either list though, the issue that was
hiding there from the beginning is triggered resulting a jump to a
memory address that isn't part of the kernel at all.

The list of features/erratas only contained an unused name and the
pointer to the check function, so an easy solution for the problem
is to just unroll the loop in code, dismantle the whole list structure
and just call the relevant check functions one by one ourself.

For the T-Head errata this includes moving the stage-check inside
the check functions.

The issue is only relevant for things that might be called for early-
alternatives (T-Head and possible future main extensions), so the
SiFive erratas were not affected from the beginning, as they got
an early return for early-alternatives in the original patchset.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Tested-by: Samuel Holland <samuel@sholland.org>
Link: https://lore.kernel.org/r/20220526205646.258337-6-heiko@sntech.de
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2022-06-16 15:47:41 -07:00
..
alpha Cleanups (and one fix) around struct mount handling. 2022-06-04 19:00:05 -07:00
arc This set of changes updates init and user mode helper tasks to be 2022-06-03 16:03:05 -07:00
arm This set of changes updates init and user mode helper tasks to be 2022-06-03 16:03:05 -07:00
arm64 This set of changes updates init and user mode helper tasks to be 2022-06-03 16:03:05 -07:00
csky This set of changes updates init and user mode helper tasks to be 2022-06-03 16:03:05 -07:00
hexagon fork: Generalize PF_IO_WORKER handling 2022-05-07 09:01:59 -05:00
ia64 Bitmap patches for 5.19-rc1 2022-06-04 14:04:27 -07:00
loongarch LoongArch: Add Loongson-3 default config file 2022-06-03 20:09:29 +08:00
m68k This set of changes updates init and user mode helper tasks to be 2022-06-03 16:03:05 -07:00
microblaze This set of changes updates init and user mode helper tasks to be 2022-06-03 16:03:05 -07:00
mips This set of changes updates init and user mode helper tasks to be 2022-06-03 16:03:05 -07:00
nios2 This set of changes updates init and user mode helper tasks to be 2022-06-03 16:03:05 -07:00
openrisc This set of changes updates init and user mode helper tasks to be 2022-06-03 16:03:05 -07:00
parisc Kbuild updates for v5.19 (2nd) 2022-06-05 09:06:03 -07:00
powerpc This set of changes updates init and user mode helper tasks to be 2022-06-03 16:03:05 -07:00
riscv riscv: remove usage of function-pointers from cpufeatures and t-head errata 2022-06-16 15:47:41 -07:00
s390 Bitmap patches for 5.19-rc1 2022-06-04 14:04:27 -07:00
sh This set of changes updates init and user mode helper tasks to be 2022-06-03 16:03:05 -07:00
sparc This set of changes updates init and user mode helper tasks to be 2022-06-03 16:03:05 -07:00
um While looking at the ptrace problems with PREEMPT_RT and the problems 2022-06-03 16:13:25 -07:00
x86 Hot fixes for 5.19-rc1. 2022-06-05 17:05:38 -07:00
xtensa While looking at the ptrace problems with PREEMPT_RT and the problems 2022-06-03 16:13:25 -07:00
.gitignore
Kconfig A set of objtool fixes: 2022-06-05 09:45:27 -07:00