[PATCH] x86/purgatory: Return bool from verify_sha256_digest()

[PATCH] x86/purgatory: Return bool from verify_sha256_digest()

[Thorsten Blum]

Change the function's return type from int to bool and return the result
of memcmp() directly to simplify the code.  While at it, cast ->start to
const u8 * to better match the expected type.

Also inline the verify_sha256_digest() check and remove the redundant
local ret variable in purgatory().

Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
---
 arch/x86/purgatory/purgatory.c | 14 ++++----------
 1 file changed, 4 insertions(+), 10 deletions(-)

diff --git a/arch/x86/purgatory/purgatory.c b/arch/x86/purgatory/purgatory.c
index 655139dd0532..3ea8eb6af11f 100644
--- a/arch/x86/purgatory/purgatory.c
+++ b/arch/x86/purgatory/purgatory.c
@@ -21,7 +21,7 @@ u8 purgatory_sha256_digest[SHA256_DIGEST_SIZE] __section(".kexec-purgatory");
 
 struct kexec_sha_region purgatory_sha_regions[KEXEC_SEGMENT_MAX] __section(".kexec-purgatory");
 
-static int verify_sha256_digest(void)
+static bool verify_sha256_digest(void)
 {
 	struct kexec_sha_region *ptr, *end;
 	u8 digest[SHA256_DIGEST_SIZE];
@@ -31,22 +31,16 @@ static int verify_sha256_digest(void)
 	end = purgatory_sha_regions + ARRAY_SIZE(purgatory_sha_regions);
 
 	for (ptr = purgatory_sha_regions; ptr < end; ptr++)
-		sha256_update(&sctx, (uint8_t *)(ptr->start), ptr->len);
+		sha256_update(&sctx, (const u8 *)(ptr->start), ptr->len);
 
 	sha256_final(&sctx, digest);
 
-	if (memcmp(digest, purgatory_sha256_digest, sizeof(digest)))
-		return 1;
-
-	return 0;
+	return memcmp(digest, purgatory_sha256_digest, sizeof(digest)) == 0;
 }
 
 void purgatory(void)
 {
-	int ret;
-
-	ret = verify_sha256_digest();
-	if (ret) {
+	if (!verify_sha256_digest()) {
 		/* loop forever */
 		for (;;)
 			;

Re: [PATCH] x86/purgatory: Return bool from verify_sha256_digest()

[Ingo Molnar]

* Thorsten Blum <thorsten.blum@linux.dev> wrote:

> -	if (memcmp(digest, purgatory_sha256_digest, sizeof(digest)))
> -		return 1;
> -
> -	return 0;
> +	return memcmp(digest, purgatory_sha256_digest, sizeof(digest)) == 0;

Could you please write this as !memcmp()? The == 0 variant is
quite a bad pattern for such a long line, as it's far easier
to miss during review than a ! unary operator...

Just like here:

> +	if (!verify_sha256_digest()) {

Thanks,

	Ingo