From ed31fb184b6eab62dfb9604203554531761d7ca9 Mon Sep 17 00:00:00 2001
From: John Reiser <jreiser@BitWagon.com>
Date: Sun, 9 Apr 2017 18:06:16 -0700
Subject: [PATCH] Replace crumb with b_info

	modified:   stub/src/arm.v4a-linux.elf-entry.S
	modified:   stub/src/arm.v4a-linux.elf-fold.S
---
 src/stub/src/arm.v4a-linux.elf-entry.S | 18 +++++++------
 src/stub/src/arm.v4a-linux.elf-fold.S  | 37 +++++++++++++++++++-------
 2 files changed, 37 insertions(+), 18 deletions(-)

diff --git a/src/stub/src/arm.v4a-linux.elf-entry.S b/src/stub/src/arm.v4a-linux.elf-entry.S
index a2acd563..c36a48b1 100644
--- a/src/stub/src/arm.v4a-linux.elf-entry.S
+++ b/src/stub/src/arm.v4a-linux.elf-entry.S
@@ -96,15 +96,14 @@ _start: .globl _start
         ldr r3,[r11,# sz_unc]
         sub r9,r12,r1  // &our_Elf32_Ehdr
         add r1,r1,r3  // sz_pack2 + cpr0.sz_unc
+        ldr r3,[r11,#o_binfo - cpr0]
         mov r0,r2  // ADRM
+        add r3,r3,r9  // &b_info for Elf32_Ehdr
         add r1,r1,# PAGE_SIZE
-  section LUNMP000
-        mov r3,#0<<12  // 0-page crumb
-  section LUNMP001
-        mov r3,#1<<12  // 1-page crumb
   section ELFMAINXu
-        stmdb sp!,{r0,r1,r2,r3,lr}  // ADRU,LENU,space for sz_unc,crumb,MFLG
+        stmdb sp!,{r0,r1,r2,r3,lr}  // ADRU,LENU,space for sz_unc,&b_info,MFLG
 SP_MFLG= 4*4
+D_b_info=3*4  // stack displacement to b_info
 D_sz_unc=2*4  // stack displacement to sz_unc
         mov r2,#PROT_READ | PROT_WRITE | PROT_EXEC
         ldr r3,[r12, #mflg - (start_params -4)]  // MAP_{PRIVATE|ANON}
@@ -144,9 +143,7 @@ copy:
         swi __ARM_NR_cacheflush
 #endif  /*}*/
 
-        ldr r9,[r12]  // sz_pack2
-        sub r9,r9,#sz_Elf32_Ehdr + 2*sz_Elf32_Phdr + sz_l_info + sz_p_info
-        sub r10,r12,r9  // &b_info
+        ldr r10,[sp,#D_b_info]
         add r10,r10,r4  // relocated &b_info
 
         ldr r0,[r11,# b_method ]  // 5th param (whole word: endian issues!)
@@ -162,6 +159,9 @@ D_stm1=2*4
         stmdb sp!,{TRACE_REGS}; mov r0,#3; bl trace
 #endif  /*}*/
         mov lr,pc; mov pc,r5  // decompress folded code [opcode 'blx' not in v4a]
+#if DEBUG  /*{*/
+        stmdb sp!,{TRACE_REGS}; mov r0,#4; bl trace
+#endif  /*}*/
         ldmia sp!,{r1, pc}  // discard 5th param; goto unfolded
 
 #if DEBUG  /*{*/
@@ -262,6 +262,8 @@ L71:
         /* IDENTSTR goes here */
 
   section ELFMAINZ
+o_binfo:
+        .long O_BINFO  // .int4
 cpr0: .globl cpr0
         /* { b_info={sz_unc, sz_cpr, {4 char}}, folded_loader...} */
 
diff --git a/src/stub/src/arm.v4a-linux.elf-fold.S b/src/stub/src/arm.v4a-linux.elf-fold.S
index f1061c98..8d91b789 100644
--- a/src/stub/src/arm.v4a-linux.elf-fold.S
+++ b/src/stub/src/arm.v4a-linux.elf-fold.S
@@ -49,6 +49,7 @@ O_RDONLY=       0
 
 PAGE_SHIFT= 12
 PAGE_SIZE = -(~0<<PAGE_SHIFT)
+PATHMAX=  4096
 
 #ifndef DEBUG  /*{*/
 #define DEBUG 0
@@ -61,13 +62,17 @@ PAGE_SIZE = -(~0<<PAGE_SHIFT)
 #define MAX_ELF_HDR 512
 
 fold_begin:
+#if DEBUG  //{
+#define TRACE_REGS r0-r12,r14,r15
+        stmdb sp!,{TRACE_REGS}; mov r0,#5; bl trace
+#endif  //}
 /* In:
    r10= &b_info of first compressed block (after move)
     r9= total size of compressed data
     r5= f_decompress
-    sp/ ADRU,LENU,sz_unc,crumb,MFLG,argc,argv...
+    sp/ ADRU,LENU,sz_unc,&b_info,MFLG,argc,argv...
 */
-        ldmia sp!,{r3,r4,r6,r7,r8,r11}  @ ADRU,LENU,sz_unc,crumb,MFLG,argc
+        ldmia sp!,{r3,r4,r6,r7,r8,r11}  @ ADRU,LENU,sz_unc,&b_info,MFLG,argc
         mov r0,sp  @ current stack pointer
 
         add r1,sp,r11,lsl #2  @ skip argv pointers
@@ -79,7 +84,10 @@ fold_begin:
         ldr r2,[r1],#8
         cmp r2,#0; bne .L20
 
-        sub r0,r1,#4096 @ buffer for readlink
+#if DEBUG  //{
+        stmdb sp!,{TRACE_REGS}; mov r0,#6; bl trace
+#endif  //}
+        sub r0,r1,#PATHMAX @ buffer for readlink
         sub r0,r0,#4  @ space for copy of space3eq
         sub r1,r1,sp  @ amount needed for argv,env,auxv
         mov r0,r0,lsr #2+ PAGE_SHIFT  @ 2+ because hardware might require
@@ -94,7 +102,10 @@ fold_begin:
         sub r0,r0,r2  @ new_argv with same 8-byte alignment as old_argv
         mov sp,r0
 
-        stmdb sp!,{r3,r4,r6,r7,r11}  @ ADRU,LENU,sz_unc,crumb,argc;  drop MFLG
+        stmdb sp!,{r3,r4,r6,r7,r11}  @ ADRU,LENU,sz_unc,&b_info,argc;  drop MFLG
+#if DEBUG  //{
+        stmdb sp!,{TRACE_REGS}; mov r0,#7; bl trace
+#endif  //}
 SP_sz_unc= 2*4
 SP_argc= 4*4
 
@@ -120,6 +131,9 @@ SP_argc= 4*4
         cmp r2,#0; bne .Laux
 
         str r0,[sp,#SP_sz_unc]  @ clobber sz_unc with 1+ &Elf32_auxv_t[AT_NULL@.a_type]
+#if DEBUG  //{
+        stmdb sp!,{TRACE_REGS}; mov r0,#8; bl trace
+#endif  //}
 
         add r1,r0,#1<<(2+ PAGE_SHIFT)  @ after the page
         str r1,[r4]  @ new env ptr
@@ -127,7 +141,7 @@ SP_argc= 4*4
         ldr r2,space3eq
         str r2,[r1],#4  @ "   =" of new env var
 
-        mov r2,#4096  @ buffer length
+        mov r2,#PATHMAX  @ buffer length
         adr r0,proc_self_exe
         sub r2,r2,#1  @ room for null terminator
         bl readlink; cmn r0,#4096; bcs 0f  @ error
@@ -170,7 +184,13 @@ SP_argc= 4*4
 #endif  /*}*/
         stmdb sp!,{r3,r4,r5,r6,r7,r8,r9,r10,r11,r12}
         ldmia sp!,{r0,r1,r2,r3}
+#if DEBUG  //{
+        stmdb sp!,{TRACE_REGS}; mov r0,#9; bl trace
+#endif  //}
         bl upx_main
+#if DEBUG  //{
+        stmdb sp!,{TRACE_REGS}; mov r0,#10; bl trace
+#endif  //}
         mov lr,r0  @ entry address
         add sp,sp,#(10-4)*4
         add sp,sp,#MAX_ELF_HDR + OVERHEAD  @ un-alloca
@@ -184,16 +204,13 @@ SP_argc= 4*4
         do_sys7t2 __ARM_NR_cacheflush  @ scribble r7
 #endif  //}
 
-        ldmia sp!,{r0,r1,r2,r3}  @ ADRU,LENU,1+ &Elf32_auxv_t[AT_NULL@.a_type],crumb
-        add r0,r0,r3  @ ADRU+=crumb
-        sub r1,r1,r3  @ LENU-=crumb
+        ldmia sp!,{r0,r1,r2,r3}  @ ADRU,LENU,1+ &Elf32_auxv_t[AT_NULL@.a_type],&b_info
 
 #if DEBUG  /*{*/
         ldr r3,[r2,#4 -2*4]  @ Elf32_auxv_t[AT_NULL@.a_type].a_val
         ldr r4,[r3,#0]  @ 1st instr
         ldr r5,[r3,#4]  @ 2nd instr
-#define TRACE_REGS r0-r12,r14,r15
-        stmdb sp!,{TRACE_REGS}; mov r0,#4; bl trace
+        stmdb sp!,{TRACE_REGS}; mov r0,#9; bl trace
 #endif  /*}*/
         mov r3,#0  @ clear registers: paranoia
         mov r4,#0