[newlib-cygwin] Align libgloss/arm and libc/sys/arm sources: Fix GetCmdLine semihosting directives

[newlib-cygwin] Align libgloss/arm and libc/sys/arm sources: Fix GetCmdLine semihosting directives

[Richard Earnshaw]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=37e80fbb1c329ab39d154a78fa6d99f28d220dfe

commit 37e80fbb1c329ab39d154a78fa6d99f28d220dfe
Author: Alexander Fedotov <alfedotov@gmail.com>
Date:   Fri Aug 2 07:33:43 2019 -0500

    Align libgloss/arm and libc/sys/arm sources: Fix GetCmdLine semihosting directives
    
    Applied changes from the commit 9b11672:
    
    	When simulating arm code, the target program startup code (crt0) uses
    	semihosting invocations to get the command line from the simulator. The
    	simulator returns the command line and its size into the area passed in
    	parameter. (ARM 32-bit specifications :
    	http://infocenter.arm.com/help/topic/com.arm.doc.dui0058d/DUI0058.pdf
    	chapter "5.4.19 SYS_GET_CMDLINE").
    
    	The memory area pointed by the semihosting register argument is located
    	in .text section (usually not writtable (RX)).
    
    	If we run this code on a simulator that respects this rights properties
    	(qemu user-mode for instance), the command line will not be written to
    	the .text program memory, in particular the length of the string. The
    	program runs with an empty command line. This problem hasn't been seen
    	earlier probably because qemu user-mode is not so much used, but this can
    	happen with another simulator that refuse to write in a read-only segment.
    
    	With this modification, the command line can be correctly passed to the
    	target program.
    
    	Changes:
    	- newlib/libc/sys/arm/crt0.S : Arguments passed to the
    	AngelSWI_Reason_GetCmdLine semihosting invocation are placed into .data
    	section instead of .text

Diff:
---
 newlib/libc/sys/arm/crt0.S | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/newlib/libc/sys/arm/crt0.S b/newlib/libc/sys/arm/crt0.S
index 9c26242..40bbc3d 100644
--- a/newlib/libc/sys/arm/crt0.S
+++ b/newlib/libc/sys/arm/crt0.S
@@ -393,13 +393,14 @@ __change_mode:
 	movs	r1, r0
 #else
 	movs	r0, #AngelSWI_Reason_GetCmdLine
-	adr	r1, .LC30	/* Space for command line.  */
+	ldr	r1, .LC30	/* Space for command line.  */
 #ifdef THUMB_VXM
 	bkpt	AngelSWI
 #else
  	AngelSWIAsm	AngelSWI
 #endif
 	ldr	r1, .LC30
+	ldr	r1, [r1]
 #endif
 	/*  Parse string at r1.  */
 	movs	r0, #0		/* Count of arguments so far.  */
@@ -586,8 +587,7 @@ change_back:
 #endif
 #ifdef ARM_RDI_MONITOR
 .LC30:
-	.word	CommandLine
-	.word	255
+	.word	AngelSWIArgs
 .LC31:
 	.word	__end__
 
@@ -600,6 +600,9 @@ HeapLimit:	.word	0
 __stack_base__:	.word	0
 StackLimit:	.word	0
 CommandLine:	.space	256,0	/*  Maximum length of 255 chars handled.  */
+AngelSWIArgs:
+	.word	CommandLine
+	.word	255
 #endif
 	
 #ifdef __pe__