arm64: Decouple MMU functions from memranges

The current arm64 MMU interface is difficult to use in pre-RAM
environments. It is based on the memranges API which makes use of
malloc(), and early stages usually don't have a heap. It is also built
as a one-shot interface that requires all memory ranges to be laid out
beforehand, which is a problem when existing areas need to change (e.g.
after initializing DRAM).

The long-term goal of this patch is to completely switch to a
configure-as-you-go interface based on the mmu_config_range() function,
similar to what ARM32 does. As a first step this feature is added
side-by-side to the existing interface so that existing SoC
implementations continue to work and can be slowly ported over one by
one. Like the ARM32 version it does not garbage collect page tables that
become unused, so repeated mapping at different granularities will
exhaust the available table space (this is presumed to be a reasonable
limitation for a firmware environment and keeps the code much simpler).

Also do some cleanup, align comments between coreboot and libpayload for
easier diffing, and change all error cases to assert()s. Right now the
code just propagates error codes up the stack until it eventually
reaches a function that doesn't check them anymore. MMU configuration
errors (essentially just misaligned requests and running out of table
space) should always be compile-time programming errors, so failing hard
and fast seems like the best way to deal with them.

BRANCH=None
BUG=None
TEST=Compile-tested rush_ryu. Booted on Oak and hacked MMU init to use
mmu_config_range() insted of memranges. Confirmed that CRCs over all page
tables before and after the change are equal.

Change-Id: I93585b44a277c1d96d31ee9c3dd2522b5e10085b
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: f10fcba107aba1f3ea239471cb5a4f9239809539
Original-Change-Id: I6a2a11e3b94e6ae9e1553871f0cccd3b556b3e65
Original-Signed-off-by: Julius Werner <jwerner@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/271991
Original-Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/10304
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/src/arch/arm64/include/armv8/arch/mmu.h b/src/arch/arm64/include/armv8/arch/mmu.h
index c487c1fe3b..f5111aef88 100644
--- a/src/arch/arm64/include/armv8/arch/mmu.h
+++ b/src/arch/arm64/include/armv8/arch/mmu.h
@@ -148,5 +148,7 @@
 void mmu_init(struct memranges *ranges, uint64_t *ttb, uint64_t ttb_size);
 /* Enable the mmu based on previous mmu_init(). */
 void mmu_enable(void);
+/* Change a memory type for a range of bytes at runtime. */
+void mmu_config_range(void *start, size_t size, uint64_t tag);
 
 #endif // __ARCH_ARM64_MMU_H__