Messages in this thread Patch in this message | | | Date | Thu, 13 Mar 2014 11:20:20 +0000 | From | Catalin Marinas <> | Subject | Re: [RFC PATCH] arm64: Fix __addr_ok and __range_ok macros |
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On Wed, Mar 05, 2014 at 10:41:28PM +0000, Christopher Covington wrote: > --- a/arch/arm64/include/asm/uaccess.h > +++ b/arch/arm64/include/asm/uaccess.h > @@ -66,12 +66,12 @@ static inline void set_fs(mm_segment_t fs) > #define segment_eq(a,b) ((a) == (b)) > > /* > - * Return 1 if addr < current->addr_limit, 0 otherwise. > + * Return 1 if addr <= current->addr_limit, 0 otherwise. > */ > #define __addr_ok(addr) \ > ({ \ > unsigned long flag; \ > - asm("cmp %1, %0; cset %0, lo" \ > + asm("cmp %1, %0; cset %0, ls" \ > : "=&r" (flag) \ > : "r" (addr), "0" (current_thread_info()->addr_limit) \ > : "cc"); \
As Will said, this doesn't look right. Why do you need TASK_SIZE_64 to be valid?
> @@ -83,7 +83,7 @@ static inline void set_fs(mm_segment_t fs) > * Returns 1 if the range is valid, 0 otherwise. > * > * This is equivalent to the following test: > - * (u65)addr + (u65)size < (u65)current->addr_limit > + * (u65)addr + (u65)size <= current->addr_limit > * > * This needs 65-bit arithmetic. > */ > @@ -91,7 +91,7 @@ static inline void set_fs(mm_segment_t fs) > ({ \ > unsigned long flag, roksum; \ > __chk_user_ptr(addr); \ > - asm("adds %1, %1, %3; ccmp %1, %4, #2, cc; cset %0, cc" \ > + asm("adds %1, %1, %3; ccmp %1, %4, #3, cc; cset %0, ls" \ > : "=&r" (flag), "=&r" (roksum) \ > : "1" (addr), "Ir" (size), \ > "r" (current_thread_info()->addr_limit) \
Just trying to understand: if adds does not set the C flag, we go on and do the ccmp. If addr + size <= addr_limit, "cset ls" sets the flag variable. If addr + size actually sets the C flag, we need to make sure that "cset ls" doesn't trigger, which would mean to set C flag and clear Z flag. So why do you change the ccmp flags from #2 to #3? It looks to me like #2 is enough.
-- Catalin
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