[coreboot-gerrit] Change in coreboot[master]: security/vboot: Add Kconfig symbol to set hashing block size

[Felix Held (Code Review)]

Felix Held has submitted this change. ( https://review.coreboot.org/c/coreboot/+/46901 )

Change subject: security/vboot: Add Kconfig symbol to set hashing block size
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security/vboot: Add Kconfig symbol to set hashing block size

Generally, this size probably doesn't matter very much, but in the
case of picasso's psp_verstage, the hash is being calculated by
hardware using relatively expensive system calls.  By increasing the
block size, we can save roughly 140ms of boot and resume time.

TEST=Build & boot see that boot time has decreased.
BRANCH=Zork
BUG=b:169217270 - Zork: SHA calculation in vboot takes too long

Signed-off-by: Martin Roth 
Change-Id: I68eecbbdfadcbf14288dc6e849397724fb66e0b2
Reviewed-on: https://review.coreboot.org/c/coreboot/+/46901
Tested-by: build bot (Jenkins) 
Reviewed-by: Furquan Shaikh 
Reviewed-by: Kangheui Won 
---
M src/security/vboot/Kconfig
M src/security/vboot/vboot_logic.c
2 files changed, 12 insertions(+), 3 deletions(-)

Approvals:
  build bot (Jenkins): Verified
  Furquan Shaikh: Looks good to me, approved
  Kangheui Won: Looks good to me, but someone else must approve

diff --git a/src/security/vboot/Kconfig b/src/security/vboot/Kconfig
index 094cbb9..e774478 100644
--- a/src/security/vboot/Kconfig
+++ b/src/security/vboot/Kconfig
@@ -369,6 +369,17 @@
    hex "Keyblock preamble flags"
    default 0x0

+config VBOOT_HASH_BLOCK_SIZE
+	hex
+	default 0x400
+	help
+	  Set the default hash size.  Generally 1k is reasonable, but in some
+	  cases it may improve hashing speed to increase the size.
+
+	  Note that this buffer is allocated in the stack.  Although the
+	  build should fail if the stack size is exceeded, it's something to
+	  be aware of when changing the size.
+
 endmenu # Keys
 endif # VBOOT
 endmenu # Verified Boot (vboot)
diff --git a/src/security/vboot/vboot_logic.c b/src/security/vboot/vboot_logic.c
index dbaa883..54c8224 100644
--- a/src/security/vboot/vboot_logic.c
+++ b/src/security/vboot/vboot_logic.c
@@ -19,8 +19,6 @@
 /* The max hash size to expect is for SHA512. */
 #define VBOOT_MAX_HASH_SIZE VB2_SHA512_DIGEST_SIZE

-#define TODO_BLOCK_SIZE 1024
-
 /* exports */

vb2_error_t vb2ex_read_resource(struct vb2_context *ctx,
@@ -144,7 +142,7 @@
 {
    uint64_t load_ts;
    uint32_t remaining;
-	uint8_t block[TODO_BLOCK_SIZE];
+	uint8_t block[CONFIG_VBOOT_HASH_BLOCK_SIZE];
    uint8_t hash_digest[VBOOT_MAX_HASH_SIZE];
    const size_t hash_digest_sz = sizeof(hash_digest);
    size_t block_size = sizeof(block);