On Wednesday 18 January 2012 04:02:32 Srikar Dronamraju wrote:
> > Can we use existing SET_IP() instead of set_instruction_pointer() ?
>
> Oleg had already commented about this in one his uprobes reviews.
>
> The GET_IP/SET_IP available in include/asm-generic/ptrace.h doesnt work
> on all archs. Atleast it doesnt work on powerpc when I tried it.
so migrate the arches you need over to it.
> Also most archs define instruction_pointer(). So I thought (rather Peter
> Zijlstra suggested the name set_instruction_pointer())
> set_instruction_pointer was a better bet than SET_IP. I
asm-generic/ptrace.h already has instruction_pointer_set()
> Also I dont see any usage for SET_IP/GET_IP.
i think you mean "users" here ? the usage should be fairly obvious. both
macros are used by asm-generic/ptrace.h internally, but (currently) rarely
defined by arches themselves (by design). the funcs that are based on these
GET/SET helpers though do get used in many places.
simply grep arch/*/include/asm/ptrace.h
> May be we should have something like this in
> include/asm-generic/ptrace.h
>
> #ifdef instruction_pointer
> #define GET_IP(regs) (instruction_pointer(regs))
> #define set_instruction_pointer(regs, val) (instruction_pointer(regs) =
> (val))
> #define SET_IP(regs, val) (set_instruction_pointer(regs,val))
> #endif
>
what you propose here won't work on all arches which is the whole point of
{G,S}ET_IP in the first place. i proposed a similar idea before and was shot
down for exactly that reason. look at ia64 for an obvious example.
> or should we do away with GET_IP/SET_IP esp since there are no many
> users?
no, the point is to migrate to asm-generic/ptrace.h, not away from it.
-mike
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