[PATCH] mm/memblock: introduce PHYS_ADDR_MAX

From: Stefan Agner
Date: Fri Apr 06 2018 - 17:38:25 EST


So far code was using ULLONG_MAX and type casting to obtain a
phys_addr_t with all bits set. The typecast is necessary to
silence compiler warnings on 32-bit platforms.

Use the simpler but still type safe approach "~(phys_addr_t)0"
to create a preprocessor define for all bits set.

Suggested-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Stefan Agner <stefan@xxxxxxxx>
---
Hi,

There are about a dozen other instances of (phys_addr_t)ULLONG_MAX
accross the tree. Should I address them too?

--
Stefan

include/linux/kernel.h | 1 +
mm/memblock.c | 22 +++++++++++-----------
2 files changed, 12 insertions(+), 11 deletions(-)

diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 3fd291503576..1ba9e2d71bc9 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -29,6 +29,7 @@
#define LLONG_MIN (-LLONG_MAX - 1)
#define ULLONG_MAX (~0ULL)
#define SIZE_MAX (~(size_t)0)
+#define PHYS_ADDR_MAX (~(phys_addr_t)0)

#define U8_MAX ((u8)~0U)
#define S8_MAX ((s8)(U8_MAX>>1))
diff --git a/mm/memblock.c b/mm/memblock.c
index 696829a198ba..957587178b36 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -67,7 +67,7 @@ ulong __init_memblock choose_memblock_flags(void)
/* adjust *@size so that (@base + *@size) doesn't overflow, return new size */
static inline phys_addr_t memblock_cap_size(phys_addr_t base, phys_addr_t *size)
{
- return *size = min(*size, (phys_addr_t)ULLONG_MAX - base);
+ return *size = min(*size, PHYS_ADDR_MAX - base);
}

/*
@@ -924,7 +924,7 @@ void __init_memblock __next_mem_range(u64 *idx, int nid, ulong flags,
r = &type_b->regions[idx_b];
r_start = idx_b ? r[-1].base + r[-1].size : 0;
r_end = idx_b < type_b->cnt ?
- r->base : (phys_addr_t)ULLONG_MAX;
+ r->base : PHYS_ADDR_MAX;

/*
* if idx_b advanced past idx_a,
@@ -1040,7 +1040,7 @@ void __init_memblock __next_mem_range_rev(u64 *idx, int nid, ulong flags,
r = &type_b->regions[idx_b];
r_start = idx_b ? r[-1].base + r[-1].size : 0;
r_end = idx_b < type_b->cnt ?
- r->base : (phys_addr_t)ULLONG_MAX;
+ r->base : PHYS_ADDR_MAX;
/*
* if idx_b advanced past idx_a,
* break out to advance idx_a
@@ -1543,13 +1543,13 @@ phys_addr_t __init_memblock memblock_end_of_DRAM(void)

static phys_addr_t __init_memblock __find_max_addr(phys_addr_t limit)
{
- phys_addr_t max_addr = (phys_addr_t)ULLONG_MAX;
+ phys_addr_t max_addr = PHYS_ADDR_MAX;
struct memblock_region *r;

/*
* translate the memory @limit size into the max address within one of
* the memory memblock regions, if the @limit exceeds the total size
- * of those regions, max_addr will keep original value ULLONG_MAX
+ * of those regions, max_addr will keep original value PHYS_ADDR_MAX
*/
for_each_memblock(memory, r) {
if (limit <= r->size) {
@@ -1564,7 +1564,7 @@ static phys_addr_t __init_memblock __find_max_addr(phys_addr_t limit)

void __init memblock_enforce_memory_limit(phys_addr_t limit)
{
- phys_addr_t max_addr = (phys_addr_t)ULLONG_MAX;
+ phys_addr_t max_addr = PHYS_ADDR_MAX;

if (!limit)
return;
@@ -1572,14 +1572,14 @@ void __init memblock_enforce_memory_limit(phys_addr_t limit)
max_addr = __find_max_addr(limit);

/* @limit exceeds the total size of the memory, do nothing */
- if (max_addr == (phys_addr_t)ULLONG_MAX)
+ if (max_addr == PHYS_ADDR_MAX)
return;

/* truncate both memory and reserved regions */
memblock_remove_range(&memblock.memory, max_addr,
- (phys_addr_t)ULLONG_MAX);
+ PHYS_ADDR_MAX);
memblock_remove_range(&memblock.reserved, max_addr,
- (phys_addr_t)ULLONG_MAX);
+ PHYS_ADDR_MAX);
}

void __init memblock_cap_memory_range(phys_addr_t base, phys_addr_t size)
@@ -1607,7 +1607,7 @@ void __init memblock_cap_memory_range(phys_addr_t base, phys_addr_t size)
/* truncate the reserved regions */
memblock_remove_range(&memblock.reserved, 0, base);
memblock_remove_range(&memblock.reserved,
- base + size, (phys_addr_t)ULLONG_MAX);
+ base + size, PHYS_ADDR_MAX);
}

void __init memblock_mem_limit_remove_map(phys_addr_t limit)
@@ -1620,7 +1620,7 @@ void __init memblock_mem_limit_remove_map(phys_addr_t limit)
max_addr = __find_max_addr(limit);

/* @limit exceeds the total size of the memory, do nothing */
- if (max_addr == (phys_addr_t)ULLONG_MAX)
+ if (max_addr == PHYS_ADDR_MAX)
return;

memblock_cap_memory_range(0, max_addr);
--
2.17.0