linux-kernel - Re: [git pull] kgdb light, v5

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Date:	Sun, 10 Feb 2008 10:59:58 -0800
From:	"Ray Lee" <ray-lk@...rabbit.org>
To:	"Jan Kiszka" <jan.kiszka@....de>
Cc:	"Ingo Molnar" <mingo@...e.hu>, "Sam Ravnborg" <sam@...nborg.org>,
	linux-kernel@...r.kernel.org,
	"Linus Torvalds" <torvalds@...ux-foundation.org>,
	"Andrew Morton" <akpm@....com.au>,
	"Thomas Gleixner" <tglx@...utronix.de>,
	"Jason Wessel" <jason.wessel@...driver.com>
Subject: Re: [git pull] kgdb light, v5

On Feb 10, 2008 9:39 AM, Jan Kiszka <jan.kiszka@....de> wrote:
> Ray Lee wrote:
> > unsigned int void u64_to_hex(u64 val, unsigned char *buf)
> > {
> >          int i;
> >          for (i=15; i>=0; i--) {
> >                   buf[i] = hexchars[ val & 0x0f ];
> >                   val >>= 4;
> >          }
> >          return 16;
> > }
> > ...
> >          buf += u64_to_hex(cpu_to_be64(tmp_ll), buf);
> >
> > be clearer both visually, and code-as-intent? (And equivalent helpers
> > for u32, u16 -- though they could all be rolled into one.)
>
> Yes, will come, I just produced some ETOOMANYCHANGESATONCE issue while
> improving this. The code goes down by more than 150 lines!

Thanks for responding. I'd mentioned it twice already and gotten no
response, so wasn't sure if my microphone was on :-).

If you're feeling energetic, the same sort of cleanup can be done against:

+#ifdef __BIG_ENDIAN
+               tmp_s |= hex(*buf++) << 12;
+               tmp_s |= hex(*buf++) << 8;
+               tmp_s |= hex(*buf++) << 4;
+               tmp_s |= hex(*buf++);
+#else
+               tmp_s |= hex(*buf++) << 4;
+               tmp_s |= hex(*buf++);
+               tmp_s |= hex(*buf++) << 12;
+               tmp_s |= hex(*buf++) << 8;
+#endif
+               if (probe_kernel_write(mem, tmp_s))
+                       return ERR_PTR(-EINVAL);
+
+               mem += 2;
+       } else if ((count == 4) && (((long)mem & 3) == 0)) {
+               u32 tmp_l = 0;
+
+#ifdef __BIG_ENDIAN
+               tmp_l |= hex(*buf++) << 28;
+               tmp_l |= hex(*buf++) << 24;
+               tmp_l |= hex(*buf++) << 20;
+               tmp_l |= hex(*buf++) << 16;
+               tmp_l |= hex(*buf++) << 12;
+               tmp_l |= hex(*buf++) << 8;
+               tmp_l |= hex(*buf++) << 4;
+               tmp_l |= hex(*buf++);
+#else
+               tmp_l |= hex(*buf++) << 4;
+               tmp_l |= hex(*buf++);
+               tmp_l |= hex(*buf++) << 12;
+               tmp_l |= hex(*buf++) << 8;
+               tmp_l |= hex(*buf++) << 20;
+               tmp_l |= hex(*buf++) << 16;
+               tmp_l |= hex(*buf++) << 28;
+               tmp_l |= hex(*buf++) << 24;
+#endif
+               if (probe_kernel_write(mem, tmp_l))
+                       return ERR_PTR(-EINVAL);
+               mem += 4;

As in, write a helper to parse a hex16, hex32, hex64, then do a
be[16|32|64]_to_cpu, and probe_kernel_write the result.

u64 hex_to_u64(unsigned char *buf)
{
        int i;
        u64 val = 0;

        for (i=0; i<16; i++)
                val = val<<4 | hex(buf[i]);   /* or *buf++, take your pick */
        return val;
}

...

        if (probe_kernel_write(mem, be64_to_cpu(hex_to_u64(unsigned char *buf)))
                return ERR_PTR(-EINVAL));
        mem += 4;
        buf += 16;

Or, you know, something like that.
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