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x86/mm: Declare 'start' variable where it is used 

It is not required to initialize the local variable start in
memory_map_top_down(), as the variable will be initialized in any path
before it is used.

make clang-analyzer on x86_64 tinyconfig reports:

  arch/x86/mm/init.c:612:15: warning: Although the value stored to 'start' \
  is used in the enclosing expression, the value is never actually read \
  from 'start' [clang-analyzer-deadcode.DeadStores]

Move the variable declaration into the loop, where it is used.

No code changed:

  # arch/x86/mm/init.o:

   text    data     bss     dec     hex filename
   7105    1424   26768   35297    89e1 init.o.before
   7105    1424   26768   35297    89e1 init.o.after

md5:
   a8d76c1bb5fce9cae251780a7ee7730f  init.o.before.asm
   a8d76c1bb5fce9cae251780a7ee7730f  init.o.after.asm

 [ bp: Massage. ]

Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lkml.kernel.org/r/20200928100004.25674-1-lukas.bulwahn@gmail.com
This commit is contained in:
Lukas Bulwahn 2020-09-28 12:00:04 +02:00 committed by Borislav Petkov
parent 31d8546033
commit bab202ab87
1 changed files with 4 additions and 2 deletions
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6
arch/x86/mm/init.c
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@ -596,7 +596,7 @@ static unsigned long __init get_new_step_size(unsigned long step_size)
static void __init memory_map_top_down(unsigned long map_start, static void __init memory_map_top_down(unsigned long map_start,
unsigned long map_end) unsigned long map_end)
{ {
unsigned long real_end, start, last_start; unsigned long real_end, last_start;
unsigned long step_size; unsigned long step_size;
unsigned long addr; unsigned long addr;
unsigned long mapped_ram_size = 0; unsigned long mapped_ram_size = 0;
@ -609,7 +609,7 @@ static void __init memory_map_top_down(unsigned long map_start,
step_size = PMD_SIZE; step_size = PMD_SIZE;
max_pfn_mapped = 0; /* will get exact value next */ max_pfn_mapped = 0; /* will get exact value next */
min_pfn_mapped = real_end >> PAGE_SHIFT; min_pfn_mapped = real_end >> PAGE_SHIFT;
last_start = start = real_end; last_start = real_end;
/* /*
* We start from the top (end of memory) and go to the bottom. * We start from the top (end of memory) and go to the bottom.
@ -618,6 +618,8 @@ static void __init memory_map_top_down(unsigned long map_start,
* for page table. * for page table.
*/ */
while (last_start > map_start) { while (last_start > map_start) {
unsigned long start;
if (last_start > step_size) { if (last_start > step_size) {
start = round_down(last_start - 1, step_size); start = round_down(last_start - 1, step_size);
if (start < map_start) if (start < map_start)