To avoid trampling over interesting exception artifacts on the real
stack, our arm64 systems switch to a separate exception stack when
entering an exception handler. We don't want that to use up too much
SRAM so we just set it to 512 bytes. I mean it just prints a bunch of
registers, how much stack could it need, right?
Quite a bit it turns out. The whole vtxprintf() call stack goes pretty
deep, and aarch64 generally seems to be very generous with stack space.
Just the varargs handling seems to require 128 bytes for some reason,
and the other stuff adds up too. In the end the current implementation
takes 1008 bytes, so bump the exception stack size to 2K to make sure it
fits.
Change-Id: I910be4c5f6b29fae35eb53929c733a1bd4585377
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/37464
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Hung-Te Lin <hungte@chromium.org>
This patch reworks the arm64 exception handling to be more similar to
how it works on arm32. This includes a bunch of features like actually
saving and restoring more exception state in the exception_state
structure and supporting the same sort of partial reentrancy that is
useful for GDB. Since there's no instruction to directly load into or
store out of SP on arm64, we can't do quite the same thing where we use
that to read an exception_state_ptr variable right after exception entry
when no other register is available. But we can do something very
similar by (ab-)using the "high" stack pointer (SP_EL2) as a pointer to
the exception_state struct and providing a function to change it.
Change-Id: Ia16a1124be1824392a309ae1f4cb031547d184c1
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://review.coreboot.org/29018
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
This patch adds the new, faster architectural register accessors to
libpayload that were already added to coreboot in CB:27881. It also
hardcodes the assumption that coreboot payloads run at EL2, which has
already been hardcoded in coreboot with CB:27880 (see rationale there).
This means we can drop all the read_current/write_current stuff which
added a lot of unnecessary helpers to check the current exception level.
This patch breaks payloads that used read_current/write_current
accessors, but it seems unlikely that many payloads deal with this stuff
anyway, and it should be a trivial fix (just replace them with the
respective _el2 versions).
Also add accessors for a couple of more registers that are required to
enable debug mode while I'm here.
Change-Id: Ic9dfa48411f3805747613f03611f8a134a51cc46
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://review.coreboot.org/29017
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Some exceptions (like from calling a NULL function pointer) are easier
to narrow down with a dump of the call stack. Let's take a page out of
ARM32's book and add that feature to ARM64 as well. Also change the
output format to two register columns, to make it easier to fit a whole
exception dump on one screen.
Applying to both coreboot and libpayload and syncing the output format
between both back up.
Change-Id: I19768d13d8fa8adb84f0edda2af12f20508eb2db
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://review.coreboot.org/14931
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
This patch makes some slight changes to the exception hook interface.
The old code provides a different handler hook for every exception
type... however, in practice all those hook functions often need to look
very similar, so this creates more boilerplate than it removes. The new
interface just allows for a single hook with the exception type passed
as an argument, and the consumer can signal whether the exception was
handled through the return value. (Right now this still only supports
one consumer, but it could easily be extended to walk through a list of
hooks if the need arises.)
Also move the excepton state from an argument to a global. This avoids a
lot of boilerplate since some consumers need to change the state from
many places, so they would have to pass the same pointer around many
times. It also removes the false suggestion that the exception state was
not global and you could have multiple copies of it (which the exception
core doesn't support for any architecture).
On the ARM side, the exception state is separated from the exception
stack for easier access. (This requires some assembly changes, and I
threw in a few comments and corrected the immediate sigils from '$' to
the official '#' while I'm there.) Since the exception state is now both
stored and loaded through an indirection pointer, this allows for some
very limited reentrance (you could point it to a different struct while
handling an exception, and while you still won't be able to return to
the outer-level exception from there, you could at least swap out the
pointer and return back to System Mode in one go).
BUG=chrome-os-partner:18390
TEST=Made sure normal exceptions still get dumped correctly on both
archs.
Original-Change-Id: I5d9a934fab7c14ccb2c9d7ee4b3465c825521fa2
Original-Signed-off-by: Julius Werner <jwerner@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/202562
Original-Reviewed-by: Stefan Reinauer <reinauer@chromium.org>
(cherry picked from commit 97542110f0b385b9b8d89675866e65db8ca32aeb)
Signed-off-by: Marc Jones <marc.jones@se-eng.com>
*** Squashed to prevent build failures. ***
libpayload: align arm64 with new exception handling model
The exception handling was previously updated, however the
arm64 changes raced with hat one. Make the arm64 align with
the new model. Without these changes compilation will fail.
BUG=None
BRANCH=None
TEST=Can build libpayload for rush.
Original-Change-Id: I320b39a57b985d1f87446ea7757955664f8dba8f
Original-Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/204402
Original-Reviewed-by: Furquan Shaikh <furquan@chromium.org>
Original-Commit-Queue: Furquan Shaikh <furquan@chromium.org>
(cherry picked from commit 0080df41b311ef20f9214b386fa4e38ee54aa1a1)
Signed-off-by: Marc Jones <marc.jones@se-eng.com>
Change-Id: I9a0bb3848cf5286f9f4bb08172a9f4a15278348e
Reviewed-on: http://review.coreboot.org/8117
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Julius Werner