From 5e0404ff85fca50b5ac41bf08bbe46e6de4903e7 Mon Sep 17 00:00:00 2001 From: Stephen Warren Date: Tue, 27 Aug 2019 11:54:31 -0600 Subject: board_f: fix noncached reservation calculation 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 Signed-off-by: Stephen Warren --- arch/arm/lib/cache.c | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/arm/lib/cache.c') diff --git a/arch/arm/lib/cache.c b/arch/arm/lib/cache.c index 449544d11c..463d283cb7 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; -- cgit v1.2.3