On Wed, 8 Dec 2010, Dave Martin wrote: > Hi, > > On Tue, Dec 7, 2010 at 7:15 PM, Nicolas Pitre <nicolas.pitre@xxxxxxxxxx> wrote: > > On Tue, 7 Dec 2010, Dave Martin wrote: > > > >> On Tue, Dec 7, 2010 at 2:53 PM, Dave Martin <dave.martin@xxxxxxxxxx> wrote: > >> [...] > >> > Note that converting to C doesn't mean that code which attempts to > >> > copy function bodies will work: you still need to handle the fact that > >> > if f() is a C function symbol, then the value of the symbol f is > >> > actually the function's base address + 1. See my changes in sram.c, > >> > >> To clarify, this applies *if* f is a Thumb symbol. > > > > To make it generic, a new macro could be used: > > > > #define SYM_ADDR(x) ((void *)((long)(x) & ~1L)) > > Could do ... I wasn't sure if it was useful for just this one case, > but I guess we may encounter others. And it would make the code a lot > less messy... That also makes the code self documenting. > if so, a macro for exracting just the Thumb bit, and a macro for > rebasing a symbol while preserving the Thumb bit could also be useful. > > #define SYM_STATE(x) ((long)(x) & 1) > #define SYM_REBASE(new_addr, sym) ((void *)((long)SYM_ADDR(new_addr) | > SYM_STATE(sym))) > > The relationship could be a bit clearer if we use the name SYM_BASE > instead of SYM_ADDR. > > With these, the affected code becomes something like: > > memcpy(buffer, SYM_BASE(f), size_of_f); > new_f = SYM_REBASE(f, buffer); > > What do you think? Looks fine to me. > Is there a recommended type for a pointer-sized integer? I notice > linux/types.h defines uintptr_t (as unsigned long). If uintptr_t is already defined then it is probably a good idea to just use it. Nicolas
