From: chaoskagami <chaos.kagami@gmail.com>
Date: Wed, 22 Jun 2016 04:46:32 +0000 (-0400)
Subject: Implement argc, argv[0] passing and detection of own path as PoC
X-Git-Tag: v0.2.0~58
X-Git-Url: https://chaos.moe/g/?a=commitdiff_plain;h=3635db44b0b38d5bc22559a4063d454a33d9d7ac;p=corbenik%2Fcorbenik.git

Implement argc, argv[0] passing and detection of own path as PoC
---

diff --git a/external/bits/chain.s b/external/bits/chain.s
index 5f57089..073f402 100644
--- a/external/bits/chain.s
+++ b/external/bits/chain.s
@@ -16,7 +16,6 @@
 
 .syntax unified
 .section .text
-.global copy
 copy:
     ldr r3, value
     add r1, r0, r1
@@ -51,9 +50,17 @@ boot:
         cmp r2, #4
         bcc flush_dcache
 
+    // Reload argc and argv.
+    ldr r0, argc
+    ldr r1, argv
+
     // Actually boot payload.
     ldr r3, offset
     bx r3
 
+.align 4
+
 value:  .int 0x23efffff
 offset: .int 0x23f00000
+argc:   .ascii "ARGC"
+argv:   .ascii "ARGV"
diff --git a/host/copy.sh b/host/copy.sh
index 7ff450b..1b1960d 100755
--- a/host/copy.sh
+++ b/host/copy.sh
@@ -8,15 +8,12 @@ dev=/dev/sdb
 
 mnt=/mnt/ext1
 
-mount ${dev}1 $mnt || exit 0
-cp out/arm9loaderhax.bin $mnt/arm9payload.bin || exit 0
-cp out/arm9loaderhax.bin $mnt/anim/boot/a.bin || exit 0
-cp out/arm9loaderhax.bin $mnt/anim/boot/l.bin || exit 0
-cp out/arm9loaderhax.bin $mnt/anim/boot/r.bin || exit 0
-cp out/arm9loaderhax.bin $mnt/anim/boot/none.bin || exit 0
+mount -t vfat ${dev}1 $mnt || exit 0
+cp out/arm9loaderhax.bin $mnt/arm9loaderhax.bin || exit 0
 rm -rf $mnt/corbenik
 cp -r out/corbenik $mnt/ || exit 0
 cp -r input/corbenik $mnt/ || exit 0
+cp out/arm9loaderhax.bin $mnt/corbenik/chain/Corbenik || exit 0
 umount $mnt || exit 0
 sync || exit 0
 eject ${dev} || exit 0
diff --git a/source/chain.c b/source/chain.c
index 2627d66..db80493 100644
--- a/source/chain.c
+++ b/source/chain.c
@@ -22,7 +22,7 @@ void chainload_file(char* chain_file_data) {
     char code_file[] = PATH_BITS "/chain.bin";
 
     uint8_t* bootstrap = (uint8_t*)0x24F00000;
-    uint32_t size = 0;
+    uint32_t size = 0, b_size = 0;
     uint8_t* chain_data;
 
     FILE* f = fopen(code_file, "r");
@@ -31,11 +31,11 @@ void chainload_file(char* chain_file_data) {
         abort("Missing chainloader.\n");
     }
 
-    size = fsize(f);
-    fread(bootstrap, 1, size, f);
+    b_size = fsize(f);
+    fread(bootstrap, 1, b_size, f);
     fclose(f);
 
-    chain_data = bootstrap + size;
+    chain_data = bootstrap + b_size;
 
     f = fopen(chain_file, "r");
     if (!f) {
@@ -47,9 +47,27 @@ void chainload_file(char* chain_file_data) {
     fread(chain_data, 1, size, f);
     fclose(f);
 
+    fprintf(stderr, "Setting argc, argv...\n");
+
+    size = size - (size % 4) + 4;
+
+    uint32_t* off = (uint32_t*) &chain_data[size];
+
+    off[0] = (uint32_t)off + 4; // char**
+    off[1] = (uint32_t)off + 8; // char*
+
+    char* arg0 = (char*)&off[1];
+    memcpy(arg0, chain_file, strlen(chain_file) + 1);
+
+    uint32_t* argc_off = (uint32_t*)memfind(bootstrap, b_size, "ARGC", 4);
+    uint32_t* argv_off = (uint32_t*)memfind(bootstrap, b_size, "ARGV", 4);
+
+    argc_off[0] = 1;
+    argv_off[0] = (uint32_t)off;
+
     fprintf(stderr, "Chaining to copy payload...\n");
 
-    ((void(*)())0x24F00000)(chain_data, size);
+    ((void(*)(void*, uint32_t))0x24F00000)(chain_data, size + 256 + 8); // Size of payload + argv.
 }
 
 // This function is based on PathDeleteWorker from GodMode9.
diff --git a/source/main.c b/source/main.c
index 00fd14d..9788ded 100644
--- a/source/main.c
+++ b/source/main.c
@@ -13,7 +13,7 @@ int doing_autoboot = 0;
 void shut_up();
 
 int
-main()
+main(int argc, char** argv)
 {
     if (PDN_MPCORE_CFG == 7)
         is_n3ds = 1; // Enable n3ds specific options.
@@ -28,6 +28,11 @@ main()
         abort("Failed to mount SD card.\n");
     }
 
+    if (argc >= 1 && argc < 2) {
+        // Valid argc passed.
+        fprintf(stderr, "Chainloaded. Path: %s\n", argv[0]);
+    }
+
     load_config(); // Load configuration.
 
     if (CFG_BOOTENV == 7) {
diff --git a/source/start.s b/source/start.s
index bc0b91b..04e29d1 100644
--- a/source/start.s
+++ b/source/start.s
@@ -2,34 +2,42 @@
 .align 4
 .global _start
 _start:
+    ldr r2, =argc
+    str r0, [r2]
+
+    ldr r2, =argv
+    str r1, [r2]
+
     b mpu
 
-    nop
+argc: .int 0x00000000
+argv: .int 0x00000000
+
 mpu:
-    @ Change the stack pointer
+    // Change the stack pointer
     mov sp, #0x27000000
 
-    @ Disable caches / mpu
-    mrc p15, 0, r4, c1, c0, 0  @ read control register
-    bic r4, #(1<<12)           @ - instruction cache disable
-    bic r4, #(1<<2)            @ - data cache disable
-    bic r4, #(1<<0)            @ - mpu disable
-    mcr p15, 0, r4, c1, c0, 0  @ write control register
+    // Disable caches / mpu
+    mrc p15, 0, r4, c1, c0, 0  // read control register
+    bic r4, #(1<<12)           // - instruction cache disable
+    bic r4, #(1<<2)            // - data cache disable
+    bic r4, #(1<<0)            // - mpu disable
+    mcr p15, 0, r4, c1, c0, 0  // write control register
 
-    @ Give read/write access to all the memory regions
+    // Give read/write access to all the memory regions
     ldr r5, =0x33333333
-    mcr p15, 0, r5, c5, c0, 2 @ write data access
-    mcr p15, 0, r5, c5, c0, 3 @ write instruction access
+    mcr p15, 0, r5, c5, c0, 2 // write data access
+    mcr p15, 0, r5, c5, c0, 3 // write instruction access
 
-    @ Sets MPU permissions and cache settings
-    ldr r0, =0xFFFF001D	@ ffff0000 32k
-    ldr r1, =0x01FF801D	@ 01ff8000 32k
-    ldr r2, =0x08000027	@ 08000000 1M
-    ldr r3, =0x10000021	@ 10000000 128k
-    ldr r4, =0x10100025	@ 10100000 512k
-    ldr r5, =0x20000035	@ 20000000 128M
-    ldr r6, =0x1FF00027	@ 1FF00000 1M
-    ldr r7, =0x1800002D	@ 18000000 8M
+    // Sets MPU permissions and cache settings
+    ldr r0, =0xFFFF001D	// ffff0000 32k
+    ldr r1, =0x01FF801D	// 01ff8000 32k
+    ldr r2, =0x08000027	// 08000000 1M
+    ldr r3, =0x10000021	// 10000000 128k
+    ldr r4, =0x10100025	// 10100000 512k
+    ldr r5, =0x20000035	// 20000000 128M
+    ldr r6, =0x1FF00027	// 1FF00000 1M
+    ldr r7, =0x1800002D	// 18000000 8M
     mov r10, #0x25
     mov r11, #0x25
     mov r12, #0x25
@@ -41,29 +49,32 @@ mpu:
     mcr p15, 0, r5, c6, c5, 0
     mcr p15, 0, r6, c6, c6, 0
     mcr p15, 0, r7, c6, c7, 0
-    mcr p15, 0, r10, c3, c0, 0	@ Write bufferable 0, 2, 5
-    mcr p15, 0, r11, c2, c0, 0	@ Data cacheable 0, 2, 5
-    mcr p15, 0, r12, c2, c0, 1	@ Inst cacheable 0, 2, 5
+    mcr p15, 0, r10, c3, c0, 0	// Write bufferable 0, 2, 5
+    mcr p15, 0, r11, c2, c0, 0	// Data cacheable 0, 2, 5
+    mcr p15, 0, r12, c2, c0, 1	// Inst cacheable 0, 2, 5
 
-    @ Enable caches
-    mrc p15, 0, r4, c1, c0, 0  @ read control register
-    orr r4, r4, #(1<<18)       @ - itcm enable
-    orr r4, r4, #(1<<12)       @ - instruction cache enable
-    orr r4, r4, #(1<<2)        @ - data cache enable
-    orr r4, r4, #(1<<0)        @ - mpu enable
-    mcr p15, 0, r4, c1, c0, 0  @ write control register
+    // Enable caches
+    mrc p15, 0, r4, c1, c0, 0  // read control register
+    orr r4, r4, #(1<<18)       // - itcm enable
+    orr r4, r4, #(1<<12)       // - instruction cache enable
+    orr r4, r4, #(1<<2)        // - data cache enable
+    orr r4, r4, #(1<<0)        // - mpu enable
+    mcr p15, 0, r4, c1, c0, 0  // write control register
 
-    @ Flush caches
+    // Flush caches
     mov r5, #0
-    mcr p15, 0, r5, c7, c5, 0  @ flush I-cache
-    mcr p15, 0, r5, c7, c6, 0  @ flush D-cache
-    mcr p15, 0, r5, c7, c10, 4 @ drain write buffer
+    mcr p15, 0, r5, c7, c5, 0  // flush I-cache
+    mcr p15, 0, r5, c7, c6, 0  // flush D-cache
+    mcr p15, 0, r5, c7, c10, 4 // drain write buffer
 
-    @ Fixes mounting of SDMC
+    // Fixes mounting of SDMC
 	ldr r0, =0x10000020
 	mov r1, #0x340
 	str r1, [r0]
 
+    ldr r0, argc
+    ldr r1, argv
+
     bl main
 
 .die: