Messages in this thread | | | From | Andy Shevchenko <> | Date | Thu, 19 Mar 2020 15:35:03 +0200 | Subject | Re: [PATCH v11 4/8] powerpc/perf: consolidate valid_user_sp |
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On Thu, Mar 19, 2020 at 1:54 PM Michal Suchanek <msuchanek@suse.de> wrote: > > Merge the 32bit and 64bit version. > > Halve the check constants on 32bit. > > Use STACK_TOP since it is defined. > > Passing is_64 is now redundant since is_32bit_task() is used to > determine which callchain variant should be used. Use STACK_TOP and > is_32bit_task() directly. > > This removes a page from the valid 32bit area on 64bit: > #define TASK_SIZE_USER32 (0x0000000100000000UL - (1 * PAGE_SIZE)) > #define STACK_TOP_USER32 TASK_SIZE_USER32
...
> +static inline int valid_user_sp(unsigned long sp) > +{ > + bool is_64 = !is_32bit_task(); > + > + if (!sp || (sp & (is_64 ? 7 : 3)) || sp > STACK_TOP - (is_64 ? 32 : 16)) > + return 0; > + return 1; > +}
Perhaps better to read
if (!sp) return 0;
if (is_32bit_task()) { if (sp & 0x03) return 0; if (sp > STACK_TOP - 16) return 0; } else { ... }
return 1;
Other possibility:
unsigned long align = is_32bit_task() ? 3 : 7; unsigned long top = STACK_TOP - (is_32bit_task() ? 16 : 32);
return !(!sp || (sp & align) || sp > top);
-- With Best Regards, Andy Shevchenko
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