New mechanism to define SRAM/memory map with automatic bounds checking

This patch creates a new mechanism to define the static memory layout
(primarily in SRAM) for a given board, superseding the brittle mass of
Kconfigs that we were using before. The core part is a memlayout.ld file
in the mainboard directory (although boards are expected to just include
the SoC default in most cases), which is the primary linker script for
all stages (though not rmodules for now). It uses preprocessor macros
from <memlayout.h> to form a different valid linker script for all
stages while looking like a declarative, boilerplate-free map of memory
addresses to the programmer. Linker asserts will automatically guarantee
that the defined regions cannot overlap. Stages are defined with a
maximum size that will be enforced by the linker. The file serves to
both define and document the memory layout, so that the documentation
cannot go missing or out of date.

The mechanism is implemented for all boards in the ARM, ARM64 and MIPS
architectures, and should be extended onto all systems using SRAM in the
future. The CAR/XIP environment on x86 has very different requirements
and the layout is generally not as static, so it will stay like it is
and be unaffected by this patch (save for aligning some symbol names for
consistency and sharing the new common ramstage linker script include).

BUG=None
TEST=Booted normally and in recovery mode, checked suspend/resume and
the CBMEM console on Falco, Blaze (both normal and vboot2), Pinky and
Pit. Compiled Ryu, Storm and Urara, manually compared the disassemblies
with ToT and looked for red flags.

Change-Id: Ifd2276417f2036cbe9c056f17e42f051bcd20e81
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: f1e2028e7ebceeb2d71ff366150a37564595e614
Original-Change-Id: I005506add4e8fcdb74db6d5e6cb2d4cb1bd3cda5
Original-Signed-off-by: Julius Werner <jwerner@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/213370
Reviewed-on: http://review.coreboot.org/9283
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Tauner <stefan.tauner@gmx.at>
Reviewed-by: Aaron Durbin <adurbin@google.com>

1 files changed, 8 insertions, 10 deletions

diff --git a/src/soc/nvidia/tegra132/stack.S b/src/soc/nvidia/tegra132/stack.S
index 6d3cd4e446..3b877e4be6 100644
--- a/src/soc/nvidia/tegra132/stack.S
+++ b/src/soc/nvidia/tegra132/stack.S
@@ -19,21 +19,19 @@
 
 /* Macro to initialize stack, perform seeding if required and finally call the
  * function provided
- * @stack : Stack address
- * @size  : Stack size
- * @seed  : Stack seeding required (1=yes/otherwise=no)
- * @func  : Function to call after initializing stack
+ * @stack_top    : First address above the stack
+ * @stack_bottom : Lowest address on the stack
+ * @seed         : Stack seeding required (1=yes/otherwise=no)
+ * @func         : Function to call after initializing stack
  */
-.macro stack_init stack, size, seed, func
+.macro stack_init stack_top, stack_bottom, seed, func
         /* Check if stack seeding is required */
 	mov	r0, #\seed
 	cmp     r0, #1
 	bne     call_func
 	/* Stack seeding */
-	ldr     r0, \stack
-	ldr	r1, \size
-	sub	r0, r0, r1
-	ldr	r1, \stack
+	ldr     r0, =\stack_bottom
+	ldr	r1, =\stack_top
 	ldr	r2, =0xdeadbeef
 init_stack_loop:
 	str	r2, [r0]
@@ -42,6 +40,6 @@ init_stack_loop:
 	bne	init_stack_loop
 
 call_func:
-	ldr	sp, \stack /* Set up stack pointer */
+	ldr	sp, =\stack_top /* Set up stack pointer */
 	bl	\func
 .endm