commit 4610d4b7a6310f33d4efe1d7d829c54b641db2d6
author Dave Rodgman <dave.rodgman@arm.com> Mon Jan 30 09:26:48 2023 +0000
committer Dave Rodgman <dave.rodgman@arm.com> Mon Jan 30 09:26:48 2023 +0000
tree 700c64e1f5b50cf70f479c108aca6ce4981b443f
parent e28397a376bcf90f65f2e5e7f7df020fa89a8b5f

Inhibit compiler from optimising out const-time asm

Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>

library/constant_time.c

diff --git a/library/constant_time.c b/library/constant_time.c
index 7f4d509..b3bf874 100644
--- a/library/constant_time.c
+++ b/library/constant_time.c
@@ -72,9 +72,9 @@
      */
     uint32_t r;
 #if defined(__arm__) || defined(__thumb__) || defined(__thumb2__)
-    asm ("ldr %0, [%1]" : "=r" (r) : "r" (p) :);
+    asm volatile ("ldr %0, [%1]" : "=r" (r) : "r" (p) :);
 #elif defined(__aarch64__)
-    asm ("ldr %w0, [%1]" : "=r" (r) : "r" (p) :);
+    asm volatile ("ldr %w0, [%1]" : "=r" (r) : "r" (p) :);
 #endif
     return r;
 }