Current placement of entropy initialization via Zkr extension requires a
trap-based mechanism to handle absent Zkr extension case. In presence of
Smrnmi extension no trap-based mechanisms should be used before Smrnmi is
detected and enabled otherwise trap will jump to undefined location.
Move stack guard initialization into init_coldboot function body after
device tree has been parsed so we know if Zkr extension is implemented by
the platform which helps to avoid trap-based discovery.
init_coldboot() is a safe place to initialize entropy because it doesn't
return so no check of __stack_chk_guard against value on entry
will be done.
Signed-off-by: Evgeny Voevodin <evvoevod@tenstorrent.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/acd52b0f3468758bc5f09e6a45662341b31d4d87.1778176768.git.evvoevod@tenstorrent.com
Signed-off-by: Anup Patel <anup@brainfault.org>
Implement basic Resumable NMI (RNMI) handler support for the RISC-V
Smrnmi extension.
The new _trap_rnmi_handler assembly entry point saves context using the
Smrnmi MN* CSRs (MNSCRATCH, MNEPC, MNSTATUS, MNCAUSE) and returns via
mnret. It dispatches to sbi_trap_rnmi_handler(), which optionally calls
a platform-specific ops->rnmi_handler callback for actual NMI
processing. If no platform handler is registered or it fails, the
event is reported as an unhandled NMI.
The RNMI handler reuses the generic trap context structure but stores MN*
CSR values (MNEPC, MNSTATUS, MNCAUSE) into the corresponding generic
fields (mepc, mstatus, cause) for compatibility with existing trap
infrastructure.
Signed-off-by: Evgeny Voevodin <evvoevod@tenstorrent.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/050ae6d2762ba8d5b9dfb3cc1960a23aa3d6c549.1778176768.git.evvoevod@tenstorrent.com
Signed-off-by: Anup Patel <anup@brainfault.org>
