Messages in this thread | | | Date | Fri, 10 Apr 2009 21:29:39 +0200 | From | Sam Ravnborg <> | Subject | Re: [PATCH -tip] x86: acpi/sleep.c saved_magic fix overflow |
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On Sat, Apr 11, 2009 at 12:46:56AM +0530, Jaswinder Singh Rajput wrote: > On Fri, 2009-04-10 at 21:13 +0200, Sam Ravnborg wrote: > > On Fri, Apr 10, 2009 at 07:55:45PM +0200, Pavel Machek wrote: > > > On Fri 2009-04-10 23:06:55, Jaswinder Singh Rajput wrote: > > > > Impact: fix overflow > > > > > > > Constant 0x123456789abcdef0 is so big for a long. > > > > So using saved_magic 0x12345678 for both 32 and 64 bit. > > > > > > Have you tested the patch? I have feeling that this is tested from > > > assembly... Plus it is only set to long constant on 64-bit, so I don't > > > think you are fixing anything. And if your code is correct the > > > variable is write only... > > > > $ git grep saved_magic > > kernel/acpi/sleep.c: saved_magic = 0x12345678; > > kernel/acpi/sleep.c: saved_magic = 0x123456789abcdef0; > > kernel/acpi/sleep.h:extern long saved_magic; > > kernel/acpi/wakeup_32.S: movl %cs:saved_magic, %eax > > kernel/acpi/wakeup_32.S:ENTRY(saved_magic) .long 0 > > kernel/acpi/wakeup_64.S: movq saved_magic, %rax > > kernel/acpi/wakeup_64.S:ENTRY(saved_magic) .quad 0 > > > > > > wakeup_32.S: > > movl %cs:saved_magic, %eax > > cmpl $0x12345678, %eax > > > > wakeup_64.S: > > movq saved_magic, %rax > > movq $0x123456789abcdef0, %rdx > > > > So patch is obviously bogus. > > > > Sorry, I was confused by this sparse warning on 64 bit box: > > CHECK arch/x86/kernel/acpi/sleep.c > arch/x86/kernel/acpi/sleep.c:107:16: warning: constant 0x123456789abcdef0 is so big it is long > > atleast I found problem in sparse ;-)
Sparse tells you that the constant is so big it is long - correct. So rather than being implicit appending an L would make sparse happy.
So please use the constant 0x123456789abcdef0L and I think sparse is silenced. And code/functionality is the same.
Sam
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