Re: [RFC V2 6/6] mm: Drop pxd_ERROR()

On Wed, Aug 12, 2026 at 01:33:14PM +0200, David Hildenbrand (Arm) wrote:

On 8/11/26 06:21, Anshuman Khandual wrote:

quoted

pxd_ERROR() has been used in generic mm just to print the page table entry
in pxd_clear_bad() before clearing those out with pxd_clear() later. These
pxd_ERROR() macros have been provided by all platforms which basically did
the same thing.

Make pxd_clear_bad() use recently added ptval_to_str() instead for printing
page table entries thus completely dropping dependency on platform provided
pxd_ERROR() macros which can then be dropped off. First move all required
helpers in core MM into a header file which could then be used else where.

It might make sense to split this patch further up to ease review:

Patch 1) provide ptval_to_str() a header.

Patch 2) Stop using pxd_ERROR() and friends in common code, converting to
pteval_to_str()

Patch 3) Remove now unused pxd_ERROR() and friends from arch code.

Sure but the intiial platform changes which now use ptval_to_str() as well
will probably come after the Patch (2) but before the Patch (3).

...

quoted

+static inline void
+ptval_bytes_to_hex_str(char *buf, size_t buf_size, const void *entry, size_t entry_size)
+{
+	if (WARN_ON_ONCE(buf_size < entry_size * 2 + 1)) {
+		snprintf(buf, buf_size, "overflow");
+		return;
+	}
+
+	switch (entry_size) {
+	case sizeof(u32):
+		snprintf(buf, buf_size, "%08x", *(const u32 *)entry);
+		break;
+	case sizeof(u64):
+		snprintf(buf, buf_size, "%016llx", *(const u64 *)entry);
+		break;
+#if defined(__SIZEOF_INT128__)
+	case sizeof(u128):
+		snprintf(buf, buf_size, "%016llx%016llx",
+			 (unsigned long long)(*(const u128 *)entry >> 64),
+			 (unsigned long long)*(const u128 *)entry);
+		break;
+#endif
+	default:
+		snprintf(buf, buf_size, "unsupported");
+		break;
+	}
+}

Why not leave ptval_bytes_to_hex_str() in the C file for less churn for now?

Agreed - will change.

-- 
Cheers,

David

Thanks for the review.