commit e0bb1f956f75c84500278ab4cc482f833acc413f
author David Brown <david.brown@linaro.org> Tue Oct 01 15:57:01 2019 -0600
committer David Brown <davidb@davidb.org> Wed Oct 02 10:17:22 2019 -0700
tree cbe09cf17e6f1d38ded88645c764e1346b81edd7
parent 510fddb8e06d76e2442b2a4603d3e1cbefe28be4

Change BOOT_MAX_ALIGN to #define

BOOT_MAX_ALIGN is defined as

    extern const uint32_t BOOT_MAX_ALIGN;

and is assigned a value in a single file.  This causes extra work when
this is used as the size of a local variable in a function.

The value was made a constant in order for the simulator to be able to
access the value.  Instead of making it a "real" constant, keep it as a
define, unifying the value of FLASH_MAX_ALIGN and this one, and provide
an accessor function for the test code to be able to access this value.

This causes a minor improvement in the code generated in
`boot_write_status`, but more importantly, eliminates a VLA from the
code, which increases the possible compilers supported by MCUboot.

Signed-off-by: David Brown <david.brown@linaro.org>

boot/bootutil/include/bootutil/bootutil.h

diff --git a/boot/bootutil/include/bootutil/bootutil.h b/boot/bootutil/include/bootutil/bootutil.h
index 5d48124..92a9efc 100644
--- a/boot/bootutil/include/bootutil/bootutil.h
+++ b/boot/bootutil/include/bootutil/bootutil.h
@@ -50,8 +50,7 @@
 /** Swapping encountered an unrecoverable error */
 #define BOOT_SWAP_TYPE_PANIC    0xff
 
-#define MAX_FLASH_ALIGN         8
-extern const uint32_t BOOT_MAX_ALIGN;
+#define BOOT_MAX_ALIGN          8
 
 struct image_header;
 /**
@@ -75,11 +74,11 @@
  */
 struct image_trailer {
     uint8_t swap_type;
-    uint8_t pad1[MAX_FLASH_ALIGN - 1];
+    uint8_t pad1[BOOT_MAX_ALIGN - 1];
     uint8_t copy_done;
-    uint8_t pad2[MAX_FLASH_ALIGN - 1];
+    uint8_t pad2[BOOT_MAX_ALIGN - 1];
     uint8_t image_ok;
-    uint8_t pad3[MAX_FLASH_ALIGN - 1];
+    uint8_t pad3[BOOT_MAX_ALIGN - 1];
     uint8_t magic[16];
 };
 

boot/bootutil/src/bootutil_misc.c

diff --git a/boot/bootutil/src/bootutil_misc.c b/boot/bootutil/src/bootutil_misc.c
index 711dbe6..ee89444 100644
--- a/boot/bootutil/src/bootutil_misc.c
+++ b/boot/bootutil/src/bootutil_misc.c
@@ -53,7 +53,6 @@
     (sizeof boot_img_magic / sizeof boot_img_magic[0])
 
 const uint32_t BOOT_MAGIC_SZ = sizeof boot_img_magic;
-const uint32_t BOOT_MAX_ALIGN = MAX_FLASH_ALIGN;
 
 struct boot_swap_table {
     uint8_t magic_primary_slot;

sim/mcuboot-sys/csupport/run.c

diff --git a/sim/mcuboot-sys/csupport/run.c b/sim/mcuboot-sys/csupport/run.c
index d355c6e..dd63d55 100644
--- a/sim/mcuboot-sys/csupport/run.c
+++ b/sim/mcuboot-sys/csupport/run.c
@@ -449,3 +449,8 @@
         }
     }
 }
+
+uint32_t boot_max_align(void)
+{
+    return BOOT_MAX_ALIGN;
+}

sim/mcuboot-sys/src/c.rs

diff --git a/sim/mcuboot-sys/src/c.rs b/sim/mcuboot-sys/src/c.rs
index 6f92c34..3d2f3ea 100644
--- a/sim/mcuboot-sys/src/c.rs
+++ b/sim/mcuboot-sys/src/c.rs
@@ -45,7 +45,7 @@
 }
 
 pub fn boot_max_align() -> usize {
-    unsafe { raw::BOOT_MAX_ALIGN as usize }
+    unsafe { raw::boot_max_align() as usize }
 }
 
 pub fn rsa_oaep_encrypt(pubkey: &[u8], seckey: &[u8]) -> Result<[u8; 256], &'static str> {
@@ -84,7 +84,7 @@
         pub fn boot_trailer_sz(min_write_sz: u8) -> u32;
 
         pub static BOOT_MAGIC_SZ: u32;
-        pub static BOOT_MAX_ALIGN: u32;
+        pub fn boot_max_align() -> u32;
 
         pub fn rsa_oaep_encrypt_(pubkey: *const u8, pubkey_len: libc::c_uint,
                                  seckey: *const u8, seckey_len: libc::c_uint,