below / hellosilicon Goto Github PK

Embedded platforms don't do static. However, if you're still curious here's how you can convince Xcode to make those files:

diff --git a/AsMain/main.s b/AsMain/main.s
index 953236a..61760cd 100644
--- a/AsMain/main.s
+++ b/AsMain/main.s
@@ -6,12 +6,11 @@
 // X16 - Mach function number
 //
 
-.global _main	            // Provide program starting address to linker
+.global start	            // Provide program starting address to linker
 .align 2
-
 // Setup the parameters to print hello world
 // and then call Linux to do it.
-_main: mov	X0, #1	    // 1 = StdOut
+start: mov	X0, #1	    // 1 = StdOut
     adr	X1, helloworld // string to print
 	mov	X2, #13	    // length of our string
 	mov	X16, #4	    // linux write system call
diff --git a/MacAs.xcodeproj/project.pbxproj b/MacAs.xcodeproj/project.pbxproj
index 11b501e..f95d6bd 100644
--- a/MacAs.xcodeproj/project.pbxproj
+++ b/MacAs.xcodeproj/project.pbxproj
@@ -318,6 +318,8 @@
 			isa = XCBuildConfiguration;
 			buildSettings = {
 				CODE_SIGN_STYLE = Automatic;
+				LINK_WITH_STANDARD_LIBRARIES = NO;
+				OTHER_LDFLAGS = "-static";
 				PRODUCT_NAME = "$(TARGET_NAME)";
 			};
 			name = Debug;
@@ -326,6 +328,8 @@
 			isa = XCBuildConfiguration;
 			buildSettings = {
 				CODE_SIGN_STYLE = Automatic;
+				LINK_WITH_STANDARD_LIBRARIES = NO;
+				OTHER_LDFLAGS = "-static";
 				PRODUCT_NAME = "$(TARGET_NAME)";
 			};
 			name = Release;

If you put an underscore in front of main in both places and give up on static linking:

If you look at the book page 100-101, you will find that 0x1234FEDC4F5D6E3A is the correct answer. Please remove the incorrect fix. Removing the initialization of the output string makes the program completely useless.

I'm hoping you can possibly answer this question???

I've been working thru the book and your code changes in order for everything to work on the Machine We Must Not Speak About.

I'm trying to extend one of the Chapter 4 exercises and access the command line argument(s) (argc & argv) within my assembly code. I've searched high and low and just can't find anything that applies (or works).

Could you possibly provide any clues/hints on how to access the command line arguments (argv and argc) within the assembly program.

This very simple program is working fine but if you read the TODO, in the attached code, what I'm trying to do should make sense.

case.txt

Thanks much!

As the title says. The original code has this too; the kernel doesn't care about null termination.

Hi,
Is it possible to build your examples into 32-bit binary and run on Apple Silicon Mac? If yes, what's the build command? Thanks!

To be clear, I haven't used the setup in HelloSilicon, I'm just using Xcode out of the box. Still, this might be relevant here as well.
One caveat I've come across is that GAS generates local symbols for labels starting with the letter l. Thus, labels such as 'loop' are completely ignored by the debugger and breakpoint and single stepping behavior becomes weird. For example, setting a breakpoint anywhere in the loop will pause execution only at the next label in program order (say, cont in upper.s). Also, single stepping and hitting a branch back to loop (e.g. B.NE loop) doesn't get back there, but again hits the next label. Just mentioning this, since many examples in the book have loops.

I really appreciate this repository, and this isn't an issue with it as such, but I wanted to ask if anyone here can provide an actual documentation page for the assembler apple uses. It seems the mac OS X Assembler guide (old copy at http://personal.denison.edu/~bressoud/cs281-s07/Assembler.pdf )is out of date, and there isn't a meaningful guide for clang llvm assmbler (I guess, that's because it's a framework, not an assembler with macros and directives).

I sortof managed to muddle through some of the problems, but there are differences between apple's old documentation and the gas manual. E.g. macros - they can take named parameters. But you can't redefine symbols with .set (which is sometimes quite useful). I'd be great to have an authoritative manual, or alternatives to the apple assembler. E.g., is there a yasm etc that can be used ? I asked around in other places, but not much success yet.

I'm hesitant to make this an issue here, as this isn't y'all's fault. However, it seems y'all had to figure some of this out and it would be great to share any expertise you might have. If this is an unreasonable imposition, please feel free to close this without a comment.

Many thanks in advance.

I tried to adapt the openat call to Darwin, but it returns 9, regardless of the input file (i.e. even when I would be expecting an error).

I have disassembled libsystem_kernel.dylib, and didn't really get wiser:

   15548:       b7 13 40 b9     ldr     w23, [x29, #16]
   1554c:       e3 3e 00 12     and     w3, w23, #0xffff
   15550:       e0 03 15 aa     mov     x0, x21
   15554:       e1 03 14 aa     mov     x1, x20
   15558:       e2 03 13 aa     mov     x2, x19
   1555c:       27 b7 ff 97     bl      ___openat

___openat:      
    31f8:       f0 39 80 d2     mov     x16, #463 
    31fc:       01 10 00 d4     svc     #0x80
    3200:       e3 00 00 54     b.lo    0x321c

I can't really see a big difference in my call:

If anyone has an idea …

I cloned the repo, did cd HelloSilicon/Chapter\ 02, ran make then ran these commands:

objdump -d movexamps
objdump -d -M no-aliases movexamps

objdump -d --macho movexamps
objdump -d --macho -M no-aliases movexamps

These 3

objdump -d movexamps
objdump -d --macho movexamps
objdump -d --macho -M no-aliases movexamps

produce the same disassembly:

$ objdump -d movexamps

movexamps:	file format mach-o arm64

Disassembly of section __TEXT,__text:

0000000100003f7c <_start>:
100003f7c: 42 c7 8d d2 	mov	x2, #28218
100003f80: a2 eb a9 f2 	movk	x2, #20317, lsl #16
100003f84: 82 db df f2 	movk	x2, #65244, lsl #32
100003f88: 82 46 e2 f2 	movk	x2, #4660, lsl #48
100003f8c: e1 03 02 2a 	mov	w1, w2
100003f90: 41 f8 7f d3 	lsl	x1, x2, #1
100003f94: 41 fc 41 d3 	lsr	x1, x2, #1
100003f98: 41 fc 41 93 	asr	x1, x2, #1
100003f9c: 41 04 c2 93 	ror	x1, x2, #1
100003fa0: 01 60 b5 d2 	mov	x1, #2868903936
100003fa4: a1 05 80 12 	mov	w1, #-46
100003fa8: 21 00 80 12 	mov	w1, #-2
100003fac: 00 00 80 d2 	mov	x0, #0
100003fb0: 30 00 80 d2 	mov	x16, #1
100003fb4: 01 10 00 d4 	svc	#0x80
$ objdump -d --macho movexamps
movexamps:
(__TEXT,__text) section
_start:
100003f7c:	42 c7 8d d2	mov	x2, #28218
100003f80:	a2 eb a9 f2	movk	x2, #20317, lsl #16
100003f84:	82 db df f2	movk	x2, #65244, lsl #32
100003f88:	82 46 e2 f2	movk	x2, #4660, lsl #48
100003f8c:	e1 03 02 2a	mov	w1, w2
100003f90:	41 f8 7f d3	lsl	x1, x2, #1
100003f94:	41 fc 41 d3	lsr	x1, x2, #1
100003f98:	41 fc 41 93	asr	x1, x2, #1
100003f9c:	41 04 c2 93	ror	x1, x2, #1
100003fa0:	01 60 b5 d2	mov	x1, #2868903936
100003fa4:	a1 05 80 12	mov	w1, #-46
100003fa8:	21 00 80 12	mov	w1, #-2
100003fac:	00 00 80 d2	mov	x0, #0
100003fb0:	30 00 80 d2	mov	x16, #1
100003fb4:	01 10 00 d4	svc	#0x80
$ objdump -d --macho -M no-aliases movexamps
movexamps:
(__TEXT,__text) section
_start:
100003f7c:	42 c7 8d d2	mov	x2, #28218
100003f80:	a2 eb a9 f2	movk	x2, #20317, lsl #16
100003f84:	82 db df f2	movk	x2, #65244, lsl #32
100003f88:	82 46 e2 f2	movk	x2, #4660, lsl #48
100003f8c:	e1 03 02 2a	mov	w1, w2
100003f90:	41 f8 7f d3	lsl	x1, x2, #1
100003f94:	41 fc 41 d3	lsr	x1, x2, #1
100003f98:	41 fc 41 93	asr	x1, x2, #1
100003f9c:	41 04 c2 93	ror	x1, x2, #1
100003fa0:	01 60 b5 d2	mov	x1, #2868903936
100003fa4:	a1 05 80 12	mov	w1, #-46
100003fa8:	21 00 80 12	mov	w1, #-2
100003fac:	00 00 80 d2	mov	x0, #0
100003fb0:	30 00 80 d2	mov	x16, #1
100003fb4:	01 10 00 d4	svc	#0x80
$ 

Only -M no-aliases without --macho changes any instructions

$ objdump -d -M no-aliases movexamps

movexamps:	file format mach-o arm64

Disassembly of section __TEXT,__text:

0000000100003f7c <_start>:
100003f7c: 42 c7 8d d2 	mov	x2, #28218
100003f80: a2 eb a9 f2 	movk	x2, #20317, lsl #16
100003f84: 82 db df f2 	movk	x2, #65244, lsl #32
100003f88: 82 46 e2 f2 	movk	x2, #4660, lsl #48
100003f8c: e1 03 02 2a 	orr	w1, wzr, w2
100003f90: 41 f8 7f d3 	lsl	x1, x2, #1
100003f94: 41 fc 41 d3 	lsr	x1, x2, #1
100003f98: 41 fc 41 93 	asr	x1, x2, #1
100003f9c: 41 04 c2 93 	extr	x1, x2, x2, #1
100003fa0: 01 60 b5 d2 	mov	x1, #2868903936
100003fa4: a1 05 80 12 	mov	w1, #-46
100003fa8: 21 00 80 12 	mov	w1, #-2
100003fac: 00 00 80 d2 	mov	x0, #0
100003fb0: 30 00 80 d2 	mov	x16, #1
100003fb4: 01 10 00 d4 	svc	#0x80

Although it only changes mov w1, w2 -> orr w1, wzr, w2 and ror x1, x2, #1 -> extr x1, x2, x2, #1. I was promised that

but it stays the same

100003fa4: a1 05 80 12 	mov	w1, #-46
100003fa8: 21 00 80 12 	mov	w1, #-2

I'm on an M1 Macbook Air, macOS 13.2.1, Xcode version 14.1 (14B47b)

$ as --version
Apple clang version 14.0.0 (clang-1400.0.29.202)
Target: arm64-apple-darwin22.3.0
Thread model: posix
InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin
$ objdump --version
Apple LLVM version 14.0.0 (clang-1400.0.29.202)
  Optimized build.
  Default target: arm64-apple-darwin22.3.0
  Host CPU: apple-a12
[...]
$ softwareupdate --list
Software Update Tool

Finding available software
No new software available.

Well...I'm back.....this time with a problem (self-inflicted wound?)

I've been moving merrily along through your "Hello Silicon" project...learning tons (and having a blast).
Along the way I've been keeping my "MWMNSA" up-to-date with the OS betas and the Xcode betas.

My problem started this morning when I (foolishly?) installed the publicly available version of Big Sur - 11.0.1

Now all my projects fail to compile/link successfully (actually the failure is during the link phase).
Here is a sample of the error I'm getting

jeffrosengarden@MacMiniDTK Chapter 4 % make case
ld -o case -lSystem -syslibroot xcrun -sdk macosx --show-sdk-path -e _start -arch arm64 case.o
ld: warning: ignoring file /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.15.sdk/usr/lib/libSystem.tbd, missing required architecture arm64 in file /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.15.sdk/usr/lib/libSystem.tbd
ld: dynamic main executables must link with libSystem.dylib for architecture arm64
make: *** [case] Error 1

I'm not sure what to do here. Any help/advice would be greatly appreciated.

Thanks much!

I've just started reading the book and when I got to the HelloWorld I noticed that the approach for doing system calls is different.

Since the repo went to trouble of stating where the terminal is (😅), I think a brief explanation of the differences would be important.

On the book (Linux):

...
_start: mov     X0, #1          // 1 = StdOut
     ldr        X1, =helloworld // string to print
     mov        X2, #13         // length of our string
     mov        X8, #64         // Linux write system call
     svc        0               // Call Linux to output the string
...

On the HelloSillicon repo (Mac):

...
_start: mov	X0, #1		// 1 = StdOut
	adr	X1, helloworld 	// string to print
	mov	X2, #13	    	// length of our string
	mov	X16, #4		// Unix write system call
	svc	#0x80		// Call kernel to output the string
...

For starters, why the system call is different: The function number is different (64 and 4) due to each system having different conventions. The table for the Darwin (Apple) system calls can be found at the following link:Darwin System Calls.

This is however one specific version (the most recent at time of writing). Newer versions can be found at here.

Also due to system conventions, the address for storing the function numbers is different.
While on Linux is on X8, in Apple Sillicon is X16.

And for calling the interruption as well, while on Linux is 0, on Apple Sillicon is 0x80.

While the distance code works, the matrixmultneon code does not, and building it leads to the following error:

<instantiation>:1:24: error: invalid operand for instruction
MUL V6.4H, V0.4H, V3.4H[0]
                        ^

The book says:

MUL V6.4H, V0.4H, V3.4H[0]
This is multiplying each lane in V0 by the scalar contained in a specific lane of V3. This shows how we typically access a value in a specific lane by appending [lane number] to the end of the register specifier—counting lanes from zero.

Adding -arch arm64e does not change anything.

Maybe @steipete has an idea?

"The stand-alone system assemblers for i386, x86_64, and arm are deprecated and may be removed in a future Xcode release. Using the as command with the -Q flag shows a warning that instructs you to transition to Clang’s integrated assembler and the -q flag. The as(1) driver will remain, as a standard way to invoke Clang’s integrated assembler, as well as any assemblers installed by the developer. (61299833)"

Hi, I'm really new to this row level world 🙏 and have an issue.

I'm not able to use the command with options, objdump -s -d -M no-aliases filename.o, and it says "Unrecognized disassembler option: no-aliases"

I don't know why, can't I use that option on m1?

thank you, in advance.

Lines 21–23 are not required or were added by mistake, causing the program to output an incorrect string.
If we remove these three lines, the program works as expected.

Expected:
0x123456789ABCDEFG
Actual:
0x1234FEDC4F5D6E3A

I am very new to assembly; please let me know if I'm wrong somewhere.