sbi_load/store_access_handler now tries to call platform emulators
if defined. Otherwise, redirects the fault. If the platform code
returns failure, this means the H/S/U has accessed the emulated
devices in an unexpected manner, which is very likely caused by
buggy code in H/S/U. We redirect the fault, so lower privileged
level can get notified, and act accordingly. (E.g., oops in Linux)
We let the handler truly fail if the trap was originated from M mode.
In this case, something must be very wrong and we should just fail.
Signed-off-by: Bo Gan <ganboing@gmail.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
This patch allows the platform to define load/store emulators. This
enables a platform to trap-and-emulate special devices or filter
access to existing physical devices.
Signed-off-by: Bo Gan <ganboing@gmail.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
This patch abstracts out the instruction decoding part of misaligned ld/st
fault handlers, so it can be reused by ld/st access fault handlers.
Also Added lb/lbu/sb decoding. (previously unreachable by misaligned fault)
sbi_trap_emulate_load/store is now the common handler which takes a `emu`
parameter that is responsible for emulating the misaligned or access fault.
The `emu` callback is expected to fixup the fault, and based on the return
code of `emu`, sbi_trap_emulate_load/store will:
r/wlen => the fixup is successful and regs/mepc needs to be updated.
0 => the fixup is successful, but regs/mepc should be left untouched
(this is usually used if `emu` does `sbi_trap_redirect`)
-err => failed, sbi_trap_error will be called
For now, load/store access faults are blindly redirected. It will be
enhanced in the following patches.
Signed-off-by: Bo Gan <ganboing@gmail.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
This simplifies both handlers such that when the handler needs to
redirect the original trap, it's readily available.
Signed-off-by: Bo Gan <ganboing@gmail.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
sbi_trap_redirect now uses const pointer to `trap`.
This ensures the caller that we never change `trap` in sbi_trap_redirect.
Signed-off-by: Bo Gan <ganboing@gmail.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
