From 325fc118fc6a2ad914947cc4ab9464ca5cf94815 Mon Sep 17 00:00:00 2001
From: Ralph Ronnquist <ralph.ronnquist@gmail.com>
Date: Tue, 29 Mar 2022 10:37:13 +1100
Subject: [PATCH] bbonev squeeze

---
 asm/reaper.asm | 80 ++++++++++++++++++++++++++------------------------
 1 file changed, 41 insertions(+), 39 deletions(-)

diff --git a/asm/reaper.asm b/asm/reaper.asm
index 0086a8f..c5dee49 100644
--- a/asm/reaper.asm
+++ b/asm/reaper.asm
@@ -6,41 +6,32 @@
 	format elf64 executable
 	entry main
 
-	;; A data segment
-	segment readable writable
+;;; Using mixed Data and Code segment for size squeeze
 
-	;; sigset_t set -- bit mask for sigprocmask
-set:	dq -1	; all bits set
-	
-;;; siginfo_t status -- all ignored
-status:	rept 16 { dq 0 }
-status$end:
-	
-;;; A code segment
-	segment readable executable
+	segment readable writable executable
 	
 ;;; Main entry point
 main:
 	;; if (getpid() != 1) exit 1;
-	mov rax, qword 39
+	xor rax, rax
+	mov al, 39
+	; rax=39
 	syscall
-	cmp rax, 1
-	je pid_1
-	
-	;; exit(1)
-	mov rdi, qword 1
-	mov rax, qword 60
-        syscall 		; exit program
+
+	dec rax
+	jnz exit	; exit(1)
 
 	;; Continue here for pid 1 only
 pid_1:
 	;; Block all signals
 	;; sigprocmask(SIG_BLOCK, &set, 0);
-	xor rdi, rdi		; SIG_BLOCK = 0
+	; rax is already 0
+	mov rdi, rax		; SIG_BLOCK = 0
 	lea rsi, [set]		; *set
-	xor rdx, rdx		; 0
-	xor r10, r10		; 0
-	mov rax, qword 14 	; sys_rt_sigprocmask
+	mov rdx, rax		; 0
+	mov r10, rax		; 0
+	mov al, 14			; sys_rt_sigprocmask
+	; rax=14, rdi=0, rsi=[set], rdx=0, r10=0
 	syscall
 
 	;; loop waiting for children, and reading their exit status
@@ -48,26 +39,37 @@ reaper:
 	;; first clear status area again
 	cld
 	xor rax, rax
-	lea rsi, [status$end]
 	lea rdi, [status]
-clear:	stosq
-	cmp rdi,rsi
-	jl clear
+	mov rdx, rdi
+	mov rcx, rax
+	mov cl, status$end-status
+	rep stosq
 	
 	;; waitid( idtype, id, *status, options )
-	xor rdi, rdi	  ;  idtype_t idtype = P_ALL = 0
-	xor rsi, rsi	  ; int id = 0
-	lea rdx, [status] ; siginfo_t* = &status
-	mov r10, 4	  ; int options = WEXITED = 4
-	mov rax, 247	  ; waitid
+	mov rdi, rax		; idtype_t idtype = P_ALL = 0
+	mov rsi, rax		; int id = 0
+	;rdx = [status]		; siginfo_t* = &status
+	mov al, 4			; int options = WEXITED = 4
+	mov r10, rax
+	mov al, 247			; waitid
+	; rax=247, rdi=0, rsi=0, rdx=[status], r10=4
 	syscall
 
-	cmp rax,-10	  ; -10 = ECHILD (no child processes)
-	jne reaper
-
+	add rax, 10 ; -10 = ECHILD (no child processes)
+	jnz reaper
+	
+exit:	; exit(1)
+	xor rax, rax
 	mov rdi, rax
-	mov rax, qword 60
-        syscall 	; exit program
+	inc rdi
+	mov al, 60
+	syscall 	; exit(1) program
 
-;;; The rest of memory is not executable
-	segment readable writable
+	;; sigset_t set -- bit mask for sigprocmask
+set:
+	dq -1	; all bits set
+	
+;;; siginfo_t status -- all ignored
+status:
+	rept 16 { dq ? }
+status$end:
-- 
2.39.2