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Added formatting
The stack pointer is set.
The stack pointer is set.
<syntaxhighlight lang="c">
// Set the stack pointer
// Set the stack pointer
*(u32 *)sp = 0x40008000;
*(u32 *)sp = 0x40008000;
// Infinite loop
// Infinite loop
deadlock();
deadlock();
</syntaxhighlight>
=== Main ===
=== Main ===
The bootloader poisons the exception vectors, cleans up memory (.bss and init_array), sets up hardware devices (including the security engine and fuses), does all the necessary checks, generates keys and finally decrypts and executes the next stage.
The bootloader poisons the exception vectors, cleans up memory (.bss and init_array), sets up hardware devices (including the security engine and fuses), does all the necessary checks, generates keys and finally decrypts and executes the next stage.
<syntaxhighlight lang="c">
// Poison all exception vectors
// Poison all exception vectors
*(u32 *)0x6000F200 = panic();
*(u32 *)0x6000F200 = panic();
return;
return;
</syntaxhighlight>
==== Panic ====
==== Panic ====
If a panic occurs, all sensitive memory contents are cleared, the security engine and fuse programming are disabled and the boot processor is left in a halted state.
If a panic occurs, all sensitive memory contents are cleared, the security engine and fuse programming are disabled and the boot processor is left in a halted state.
<syntaxhighlight lang="c">
// Clear all stack contents
// Clear all stack contents
clear_stack();
clear_stack();
while (true)
while (true)
*(u32 *)FLOW_CTLR_HALT_COP_EVENTS = (FLOW_MODE_STOP | HALT_COP_EVENT_JTAG);
*(u32 *)FLOW_CTLR_HALT_COP_EVENTS = (FLOW_MODE_STOP | HALT_COP_EVENT_JTAG);
</syntaxhighlight>
==== Anti-downgrade ====
==== Anti-downgrade ====
After disabling fuse programming, the bootloader configures the EMC and MEM/MC. It additionally disables QSPI resets and programs a special aperture designed for AHB redirected access to IRAM.
After disabling fuse programming, the bootloader configures the EMC and MEM/MC. It additionally disables QSPI resets and programs a special aperture designed for AHB redirected access to IRAM.
<syntaxhighlight lang="c">
u32 PERIPH_CLK_SOURCE_EMC = 0x6000619C;
u32 PERIPH_CLK_SOURCE_EMC = 0x6000619C;
u32 CLK_OUT_ENB_SET_H = 0x60006328;
u32 CLK_OUT_ENB_SET_H = 0x60006328;
return mc_iram_reg_ctrl_val;
return mc_iram_reg_ctrl_val;
</syntaxhighlight>
==== Key generation ====
==== Key generation ====
Depending on [[Fuses#FUSE_RESERVED_ODM4|FUSE_RESERVED_ODM4]] and [[Fuses#FUSE_SPARE_BIT_5|FUSE_SPARE_BIT_5]] different static seeds are selected for key generation.
Depending on [[Fuses#FUSE_RESERVED_ODM4|FUSE_RESERVED_ODM4]] and [[Fuses#FUSE_SPARE_BIT_5|FUSE_SPARE_BIT_5]] different static seeds are selected for key generation.
<syntaxhighlight lang="c">
// Initialize keyslots 0x0C and 0x0D as readable
// Initialize keyslots 0x0C and 0x0D as readable
init_keyslot(0x0C, 0x15);
init_keyslot(0x0C, 0x15);
return;
return;
</syntaxhighlight>
===== generate_retail_keys =====
===== generate_retail_keys =====
See the pseudocode bellow for the detailed process.
See the pseudocode bellow for the detailed process.
<syntaxhighlight lang="c">
u32 in_addr = 0;
u32 in_addr = 0;
u32 in_size = 0;
u32 in_size = 0;
return;
return;
</syntaxhighlight>
===== generate_debug_keys =====
===== generate_debug_keys =====
See the pseudocode bellow for the detailed process.
See the pseudocode bellow for the detailed process.
<syntaxhighlight lang="c">
u32 in_addr = 0;
u32 in_addr = 0;
u32 in_size = 0;
u32 in_size = 0;
return;
return;
</syntaxhighlight>
== PK11 Blob ==
== PK11 Blob ==
The encrypted blob is prepended with it's CTR and total image size. After checking the image's size against an hardcoded value (can change on firmware updates), the image is AES-CTR decrypted and the keyslot used for decryption is immediately cleared.
The encrypted blob is prepended with it's CTR and total image size. After checking the image's size against an hardcoded value (can change on firmware updates), the image is AES-CTR decrypted and the keyslot used for decryption is immediately cleared.
<syntaxhighlight lang="c">
// Maximum encrypted blob's size on firmware version 1.0.0
// Maximum encrypted blob's size on firmware version 1.0.0
u32 max_pk11_enc_blob_size = 0x29000;
u32 max_pk11_enc_blob_size = 0x29000;
return nx_boot_addr;
return nx_boot_addr;
</syntaxhighlight>
=== Header ===
=== Header ===