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boot: Move PIC challenge to 1BL low ROM, before 2BL RAM copy
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@haxar
haxar committed Oct 7, 2022
1 parent f1ad8cf commit f3b07c0
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Showing 4 changed files with 56 additions and 103 deletions.
12 changes: 3 additions & 9 deletions boot_rom/2bBootStartBios.c
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Original file line number Diff line number Diff line change
Expand Up @@ -261,12 +261,9 @@ void BootStartBiosLoader(void)
SHA1Input(&context,(void*)(PROGRAMM_Memory_2bl+20),bootloadersize-20);
SHA1Result(&context,SHA1_result);

if (memcmp(&bootloaderChecksum[0],&SHA1_result[0],20)==0) {
// HEHE, the Image we copy'd into ram is SHA-1 hash identical, this is Optimum
BootPerformPicChallengeResponseAction();

} else {
// Bad, the checksum does not match, but we can nothing do now, we wait until PIC kills us
if (memcmp(&bootloaderChecksum[0],&SHA1_result[0],20)) {
// Bad, the checksum does not match, we did not get a valid image copied to RAM, so we stop and display an error.
setLED("rrrr");
while(1);
}

Expand Down Expand Up @@ -358,9 +355,6 @@ void BootStartBiosLoader(void)
// We are not Longer here
}

// Bad, we did not get a valid im age to RAM, we stop and display a error
//setLED("rrrr");

setLED("oooo");

// I2CTransmitWord(0x10, 0x1901); // no reset on eject
Expand Down
9 changes: 5 additions & 4 deletions boot_rom/2bBootStartup.S
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Expand Up @@ -211,8 +211,12 @@

cld

// copy everything into RAM
// Set the stack pointer to give us a valid stack
movl $0x1ffff0, %esp

call pic_challenge_response

// Copy 2BL into RAM
mov $_ram_location, %edi
mov $_start_ramcopy, %esi
mov $(_size_ramcopy + 100), %ecx
Expand Down Expand Up @@ -309,9 +313,6 @@ reload_cs:
mov %eax, %fs
mov %eax, %gs

// Set the stack pointer to give us a valid stack
movl $0x1ffff0, %esp

// Clear out .bss
xor %eax, %eax
mov $BSS_SIZE_L, %ecx
Expand Down
89 changes: 30 additions & 59 deletions boot_rom/2bPicResponseAction.c
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Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,36 @@

#include "2bload.h"

void pic_challenge_response(void)
{
register u8 x1c, x1d, x1e, x1f;
register u8 b1, b2, b3, b4;
register int i;

smbus_set_addr(0x21); /* set PIC address; read command */
smbus_read_start(0x1c);
if (!smbus_cycle_completed()) return;
x1c = smbus_read_data();
x1d = smbus_read(0x1d);
x1e = smbus_read(0x1e);
x1f = smbus_read(0x1f);

b1 = 0x33;
b2 = 0xed;
b3 = x1c << 2;
b3 ^= x1d + 0x39;
b3 ^= x1e >> 2;
b3 ^= x1f + 0x63;
b4 = x1c + 0x0b;
b4 ^= x1d >> 2;
b4 ^= x1e + 0x1b;

for (i = 0; i < 4; b1 += b2 ^ b3, b2 += b1 ^ b4, ++i);

smbus_set_addr(0x20); /* set PIC address; write command */
smbus_write(0x20, b1);
smbus_write(0x21, b2);
}

// ---------------------------- I2C -----------------------------------------------------------
//
Expand Down Expand Up @@ -85,65 +115,6 @@ int I2CTransmitWord(u8 bPicAddressI2cFormat, u16 wDataToWrite)
return ERR_I2C_ERROR_BUS;
}

// ---------------------------- PIC challenge/response -----------------------------------------------------------
//
// given four bytes, returns a u16
// LSB of return is the 'first' byte, MSB is the 'second' response byte

u16 BootPicManipulation(
u8 bC,
u8 bD,
u8 bE,
u8 bF
) {
int n=4;
u8
b1 = 0x33,
b2 = 0xed,
b3 = ((bC<<2) ^ (bD +0x39) ^ (bE >>2) ^ (bF +0x63)),
b4 = ((bC+0x0b) ^ (bD>>2) ^ (bE +0x1b))
;

while(n--) {
b1 += b2 ^ b3;
b2 += b1 ^ b4;
}

return (u16) ((((u16)b2)<<8) | b1);
}

// actual business of getting I2C data from PIC and reissuing munged version
// returns zero if all okay, else error code

int BootPerformPicChallengeResponseAction()
{
u8 bC, bD, bE, bF;
int n;

n=I2CTransmitByteGetReturn( 0x10, 0x1c );
if(n<0) return n;
bC=n;
n=I2CTransmitByteGetReturn( 0x10, 0x1d );
if(n<0) return n;
bD=n;
n=I2CTransmitByteGetReturn( 0x10, 0x1e );
if(n<0) return n;
bE=n;
n=I2CTransmitByteGetReturn( 0x10, 0x1f );
if(n<0) return n;
bF=n;

{
u16 w=BootPicManipulation(bC, bD, bE, bF);

I2CTransmitWord( 0x10, 0x2000 | (w&0xff));
I2CTransmitWord( 0x10, 0x2100 | (w>>8) );
}

// continues as part of video setup....
return ERR_SUCCESS;
}

extern int I2cSetFrontpanelLed(u8 b)
{
I2CTransmitWord( 0x10, 0x800 | b); // sequencing thanks to Jarin the Penguin!
Expand Down
49 changes: 18 additions & 31 deletions boot_rom/2bload.h
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Original file line number Diff line number Diff line change
Expand Up @@ -14,23 +14,6 @@
#include "stdint.h"
#include "cromwell_types.h"


/////////////////////////////////
// LED-flashing codes
// or these together as argument to I2cSetFrontpanelLed

enum {
I2C_LED_RED0 = 0x80,
I2C_LED_RED1 = 0x40,
I2C_LED_RED2 = 0x20,
I2C_LED_RED3 = 0x10,
I2C_LED_GREEN0 = 0x08,
I2C_LED_GREEN1 = 0x04,
I2C_LED_GREEN2 = 0x02,
I2C_LED_GREEN3 = 0x01
};

///////////////////////////////
/* BIOS-wide error codes all have b31 set */

enum {
Expand All @@ -42,10 +25,7 @@ enum {
ERR_BOOT_PIC_ALG_BROKEN = 0x80000101 // PIC algorithm did not pass its self-test
};

//////// BootPerformPicChallengeResponseAction.c

/* ---------------------------- IO primitives -----------------------------------------------------------
*/
// ---------------------------- IO primitives -----------------------------------------------------------

static INLINE void IoOutputByte(u16 wAds, u8 bValue)
{
Expand Down Expand Up @@ -167,21 +147,27 @@ static INLINE u8 smbus_read(u8 cmd)
return smbus_read_data();
}

// boot process
int BootPerformPicChallengeResponseAction(void);
// LED control (see associated enum above)
int I2cSetFrontpanelLed(u8 b);
int I2cResetFrontpanelLed(void);

////////// 2bBootStartBios.c

/* 2bBootStartBios.c */
void BootSystemInitialization(void) __attribute__((section(".reset_vector.1bl"),aligned(16),naked));
void BootStartBiosLoader(void);

///////// BootPerformPicChallengeResponseAction.c

/* 2bPicResponseAction.c */
void pic_challenge_response(void) __attribute__((section(".low_rom"),aligned(16)));
int I2CTransmitWord(u8 bPicAddressI2cFormat, u16 wDataToWrite);
int I2CTransmitByteGetReturn(u8 bPicAddressI2cFormat, u8 bDataToWrite);
/* LED control; see associated enum as argument to I2cSetFrontpanelLed */
enum {
I2C_LED_RED0 = 0x80,
I2C_LED_RED1 = 0x40,
I2C_LED_RED2 = 0x20,
I2C_LED_RED3 = 0x10,
I2C_LED_GREEN0 = 0x08,
I2C_LED_GREEN1 = 0x04,
I2C_LED_GREEN2 = 0x02,
I2C_LED_GREEN3 = 0x01
};
int I2cSetFrontpanelLed(u8 b);
int I2cResetFrontpanelLed(void);

void *memcpy(void *dest, const void *src, size_t size);
void *memset(void *dest, int data, size_t size);
Expand All @@ -191,3 +177,4 @@ extern unsigned char *BufferIN;
extern int BufferINlen;
extern unsigned char *BufferOUT;
extern int BufferOUTPos;

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