powerpc/ptrace: Fix build with gcc 4.6 (e69b742a) · Commits · 戴 / test

gcc (rightfully) complains that we are accessing beyond the end of the fpr array (we do, to access the fpscr). The only sane thing to do (whether anything in that code can be called remotely sane is debatable) is to special case fpscr and handle it as a separate statement. I initially tried to do it it by making the array access conditional to index < PT_FPSCR and using a 3rd else leg but for some reason gcc was unable to understand it and still spewed the warning. So I ended up with something a tad more intricated but it seems to build on 32-bit and on 64-bit with and without VSX. Signed-off-by:

Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/kernel/ptrace.c

+14 −4

Original line number	Diff line number	Diff line
		@@ -1497,9 +1497,14 @@ long arch_ptrace(struct task_struct *child, long request,
		if (index < PT_FPR0) {
		tmp = ptrace_get_reg(child, (int) index);
		} else {
		unsigned int fpidx = index - PT_FPR0;

		flush_fp_to_thread(child);
		if (fpidx < (PT_FPSCR - PT_FPR0))
		tmp = ((unsigned long *)child->thread.fpr)
		[TS_FPRWIDTH * (index - PT_FPR0)];
		[fpidx * TS_FPRWIDTH];
		else
		tmp = child->thread.fpscr.val;
		}
		ret = put_user(tmp, datalp);
		break;
		@@ -1525,9 +1530,14 @@ long arch_ptrace(struct task_struct *child, long request,
		if (index < PT_FPR0) {
		ret = ptrace_put_reg(child, index, data);
		} else {
		unsigned int fpidx = index - PT_FPR0;

		flush_fp_to_thread(child);
		if (fpidx < (PT_FPSCR - PT_FPR0))
		((unsigned long *)child->thread.fpr)
		[TS_FPRWIDTH * (index - PT_FPR0)] = data;
		[fpidx * TS_FPRWIDTH] = data;
		else
		child->thread.fpscr.val = data;
		ret = 0;
		}
		break;

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