From: Stephen Warren <[email protected]>
The current code in reserve_noncached() has two issues:
1) The first update of gd->start_addr_sp always rounds down to a section
start. However, the equivalent calculation in cache.c:noncached_init()
always first rounds up to a section start, then subtracts a section size.
These two calculations differ if the initial value is already rounded to
section alignment.
2) The second update of gd->start_addr_sp subtracts exactly
CONFIG_SYS_NONCACHED_MEMORY, whereas the equivalent calculation in
cache.c:noncached_init() rounds the noncached size up to section
alignment before subtracting it. The two calculations differ if the
noncached region size is not a multiple of the MMU section size.
In practice, one/both of those issues causes a practical problem on
Jetson TX1; U-Boot triggers a synchronous abort during initialization,
likely due to overlapping use of some memory region.
This change fixes both these issues by duplicating the exact calculations
from noncached_init() into reserve_noncached().
However, this fix assumes that gd->start_addr_sp on entry to
reserve_noncached() exactly matches mem_malloc_start on entry to
noncached_init(). I haven't traced the code to see whether it absolutely
guarantees this in all (or indeed any!) cases. Consequently, I added some
comments in the hope that this condition will continue to be true.
Fixes: 5f7adb5b1c02 ("board_f: reserve noncached space below malloc area")
Cc: Vikas Manocha <[email protected]>
Signed-off-by: Stephen Warren <[email protected]>
---
arch/arm/lib/cache.c | 1 +
common/board_f.c | 15 ++++++++++++---
common/board_r.c | 4 ++++
3 files changed, 17 insertions(+), 3 deletions(-)
diff --git a/arch/arm/lib/cache.c b/arch/arm/lib/cache.c
index 449544d11cff..463d283cb768 100644
--- a/arch/arm/lib/cache.c
+++ b/arch/arm/lib/cache.c
@@ -77,6 +77,7 @@ void noncached_init(void)
phys_addr_t start, end;
size_t size;
+ /* If this calculation changes, update board_f.c:reserve_noncached() */
end = ALIGN(mem_malloc_start, MMU_SECTION_SIZE) - MMU_SECTION_SIZE;
size = ALIGN(CONFIG_SYS_NONCACHED_MEMORY, MMU_SECTION_SIZE);
start = end - size;
diff --git a/common/board_f.c b/common/board_f.c
index 6867abc8e679..591f18f391e2 100644
--- a/common/board_f.c
+++ b/common/board_f.c
@@ -470,9 +470,18 @@ static int reserve_uboot(void)
#ifdef CONFIG_SYS_NONCACHED_MEMORY
static int reserve_noncached(void)
{
- /* round down to SECTION SIZE (typicaly 1MB) limit */
- gd->start_addr_sp &= ~(MMU_SECTION_SIZE - 1);
- gd->start_addr_sp -= CONFIG_SYS_NONCACHED_MEMORY;
+ /*
+ * The value of gd->start_addr_sp must match the value of malloc_start
+ * calculated in boatrd_f.c:initr_malloc(), which is passed to
+ * board_r.c:mem_malloc_init() and then used by
+ * cache.c:noncached_init()
+ *
+ * These calculations must match the code in cache.c:noncached_init()
+ */
+ gd->start_addr_sp = ALIGN(gd->start_addr_sp, MMU_SECTION_SIZE) -
+ MMU_SECTION_SIZE;
+ gd->start_addr_sp -= ALIGN(CONFIG_SYS_NONCACHED_MEMORY,
+ MMU_SECTION_SIZE);
debug("Reserving %dM for noncached_alloc() at: %08lx\n",
CONFIG_SYS_NONCACHED_MEMORY >> 20, gd->start_addr_sp);
diff --git a/common/board_r.c b/common/board_r.c
index b7f68bba4a7e..d6fb5047a265 100644
--- a/common/board_r.c
+++ b/common/board_r.c
@@ -247,6 +247,10 @@ static int initr_malloc(void)
gd->malloc_ptr / 1024);
#endif
/* The malloc area is immediately below the monitor copy in DRAM */
+ /*
+ * This value MUST match the value of gd->start_addr_sp in board_f.c:
+ * reserve_noncached().
+ */
malloc_start = gd->relocaddr - TOTAL_MALLOC_LEN;
mem_malloc_init((ulong)map_sysmem(malloc_start, TOTAL_MALLOC_LEN),
TOTAL_MALLOC_LEN);
--
2.22.1
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