diff --git a/crypto/test/abi_test.h b/crypto/test/abi_test.h
index 0d685ed..44547f8 100644
--- a/crypto/test/abi_test.h
+++ b/crypto/test/abi_test.h
@@ -109,14 +109,12 @@
 // References:
 // AAPCS: http://infocenter.arm.com/help/topic/com.arm.doc.ihi0042f/IHI0042F_aapcs.pdf
 // iOS32: https://developer.apple.com/library/archive/documentation/Xcode/Conceptual/iPhoneOSABIReference/Articles/ARMv6FunctionCallingConventions.html
+// Linux: http://sourcery.mentor.com/sgpp/lite/arm/portal/kbattach142/arm_gnu_linux_%20abi.pdf
 //
-// ARM specifies a common calling convention, except r9 is left to the
-// platform. Linux and iOS differ in handling of r9. iOS's behavior is defined
-// below. We found no clear reference for Linux but observed behavior from
-// LLVM. iOS 3+ treats r9 as caller-saved, while Linux treats it as
-// callee-saved. Most of our assembly treats it as callee-saved to be uniform,
-// but we match the platform to avoid false positives when testing
-// compiler-generated output.
+// ARM specifies a common calling convention, except r9 is left to the platform.
+// Linux treats r9 as callee-saved, while iOS 3+ treats it as caller-saved. Most
+// of our assembly treats it as callee-saved to be uniform, but we match the
+// platform to avoid false positives when testing compiler-generated output.
 #define LOOP_CALLER_STATE_REGISTERS_PRE_R9() \
   CALLER_STATE_REGISTER(uint64_t, d8)        \
   CALLER_STATE_REGISTER(uint64_t, d9)        \
diff --git a/crypto/test/asm/trampoline-armv4.pl b/crypto/test/asm/trampoline-armv4.pl
index bfa67e4..30f510e 100755
--- a/crypto/test/asm/trampoline-armv4.pl
+++ b/crypto/test/asm/trampoline-armv4.pl
@@ -27,6 +27,7 @@
 # AAPCS: http://infocenter.arm.com/help/topic/com.arm.doc.ihi0042f/IHI0042F_aapcs.pdf
 # iOS ARMv6: https://developer.apple.com/library/archive/documentation/Xcode/Conceptual/iPhoneOSABIReference/Articles/ARMv6FunctionCallingConventions.html
 # iOS ARMv7: https://developer.apple.com/library/archive/documentation/Xcode/Conceptual/iPhoneOSABIReference/Articles/ARMv7FunctionCallingConventions.html
+# Linux: http://sourcery.mentor.com/sgpp/lite/arm/portal/kbattach142/arm_gnu_linux_%20abi.pdf
 
 use strict;
 
@@ -70,10 +71,10 @@
 	stmdb	sp!, {r0-r11,lr}
 
 	@ Reserve stack space for six (10-4) stack parameters, plus an extra 4
-	@ bytes to keep it 8-byte-aligned (see APCS, section 5.3).
+	@ bytes to keep it 8-byte-aligned (see AAPCS, section 5.3).
 	sub     sp, sp, #28
 
-	@ Every register in APCS is either non-volatile or a parameter (except
+	@ Every register in AAPCS is either non-volatile or a parameter (except
 	@ r9 on iOS), so this code, by the actual call, loses all its scratch
 	@ registers. First fill in stack parameters while there are registers
 	@ to spare.