On Fri, 2012-11-16 at 14:25 -0800, H. Peter Anvin wrote: > It is a performance improvement. > > >> * kernel identity mapping to modify code. > >> */ > >> if (within(ip, (unsigned long)_text, (unsigned long)_etext)) > >> - ip = (unsigned long)__va(__pa(ip)); > >> + ip = (unsigned long)__va(__pa_symbol(ip)); > >> > >> return probe_kernel_write((void *)ip, new_code, MCOUNT_INSN_SIZE); > >> } > >> @@ -279,7 +279,7 @@ static int ftrace_write(unsigned long ip, const > >char *val, int size) > >> * kernel identity mapping to modify code. > >> */ > >> if (within(ip, (unsigned long)_text, (unsigned long)_etext)) > >> - ip = (unsigned long)__va(__pa(ip)); > >> + ip = (unsigned long)__va(__pa_symbol(ip)); > >> > >> return probe_kernel_write((void *)ip, val, size); > >> } >
#define __pa(x) __phys_addr((unsigned long)(x)) #define __pa_symbol(x) __pa(__phys_reloc_hide((unsigned long)(x))) I'm confused. __pa_symbol() just calls __pa() with some macro magic to its parameter. How is this a performance improvement? -- Steve -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
