On Thu, Jun 10, 2021 at 02:19:05PM +0100, Mark Brown wrote:

On Wed, Jun 09, 2021 at 04:17:13PM +0100, Dave Martin wrote:

quoted

On Fri, Jun 04, 2021 at 12:24:49PM +0100, Mark Brown wrote:

quoted

quoted

-		if (system_supports_bti() && has_interp == is_interp &&
-		    (*p & GNU_PROPERTY_AARCH64_FEATURE_1_BTI))
-			arch->flags |= ARM64_ELF_BTI;
+		if (system_supports_bti() &&
+		    (*p & GNU_PROPERTY_AARCH64_FEATURE_1_BTI)) {
+			if (is_interp) {
+				arch->flags |= ARM64_ELF_INTERP_BTI;
+			} else {
+				arch->flags |= ARM64_ELF_EXEC_BTI;
+			}

quoted

Nit: surplus curlies? (coding-style.rst does actually say to drop them
when all branches of an if are single-statement one-liners -- I had
presumed I was just being pedantic...)

I really think this hurts readability with the nested if inside
another if with a multi-line condition.

So long as there is a reason rather than it being purely an accident of
editing, that's fine.

(Though if the nested if can be flattened so that this becomes a non-
issue, that's good too :)

quoted

quoted

-	if (prot & PROT_EXEC)
-		prot |= PROT_BTI;
+		if (state->flags & ARM64_ELF_EXEC_BTI && !is_interp)
+			prot |= PROT_BTI;
+	}

quoted

Is it worth adding () around the bitwise-& expressions?  I'm always a
little uneasy about the operator precedence of binary &, although
without looking it up I think you're correct.

Sure.  I'm fairly sure the compiler would've complained about
this case if it were ambiguous, I'm vaguely surprised it didn't
already.

I was vaguely surprised too -- though I didn't try to compile this
myself yet.  Anyway, not a huge deal.  Adding a helper to generate the
appropriate mask would make this issue go away in any case, but so long
as you're confident this is being evaluated as intended I can take your
word for it.

quoted

Feel free to adopt if this appeals to you, otherwise I'm also fine with
your version.)

I'll see what I think when I get back to looking at this
properly.

Ack -- again, this was just a suggestion.  I can also live with your
original code if you ultimately decide to stick with that.

Cheers
---Dave

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel