linux/arch/blackfin/mach-common/head.S
Graf Yang 01b9f4b0ed Blackfin: improve double fault debug handling
Since the hardware only provides reporting for the last exception handled,
and the values are valid only when executing the exception handler, we
need to save the context for reporting at a later point.  While we do this
for one exception, it doesn't work properly when handling a second one as
the original exception is clobbered by the double fault.  So when double
fault debugging is enabled, create a dedicated shadow of these values and
save/restore out of there.  Now the crash report properly displays the
first exception as well as the second one.

Signed-off-by: Graf Yang <graf.yang@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
2009-09-16 21:31:57 -04:00

274 lines
5.1 KiB
ArmAsm

/*
* Common Blackfin startup code
*
* Copyright 2004-2008 Analog Devices Inc.
*
* Enter bugs at http://blackfin.uclinux.org/
*
* Licensed under the GPL-2 or later.
*/
#include <linux/linkage.h>
#include <linux/init.h>
#include <asm/blackfin.h>
#include <asm/thread_info.h>
#include <asm/trace.h>
#include <asm/asm-offsets.h>
__INIT
ENTRY(__init_clear_bss)
r2 = r2 - r1;
cc = r2 == 0;
if cc jump .L_bss_done;
r2 >>= 2;
p1 = r1;
p2 = r2;
lsetup (1f, 1f) lc0 = p2;
1: [p1++] = r0;
.L_bss_done:
rts;
ENDPROC(__init_clear_bss)
ENTRY(__start)
/* R0: argument of command line string, passed from uboot, save it */
R7 = R0;
/* Enable Cycle Counter and Nesting Of Interrupts */
#ifdef CONFIG_BFIN_SCRATCH_REG_CYCLES
R0 = SYSCFG_SNEN;
#else
R0 = SYSCFG_SNEN | SYSCFG_CCEN;
#endif
SYSCFG = R0;
R0 = 0;
/* Clear Out All the data and pointer Registers */
R1 = R0;
R2 = R0;
R3 = R0;
R4 = R0;
R5 = R0;
R6 = R0;
P0 = R0;
P1 = R0;
P2 = R0;
P3 = R0;
P4 = R0;
P5 = R0;
LC0 = r0;
LC1 = r0;
L0 = r0;
L1 = r0;
L2 = r0;
L3 = r0;
/* Clear Out All the DAG Registers */
B0 = r0;
B1 = r0;
B2 = r0;
B3 = r0;
I0 = r0;
I1 = r0;
I2 = r0;
I3 = r0;
M0 = r0;
M1 = r0;
M2 = r0;
M3 = r0;
/*
* Clear ITEST_COMMAND and DTEST_COMMAND registers,
* Leaving these as non-zero can confuse the emulator
*/
p0.L = LO(DTEST_COMMAND);
p0.H = HI(DTEST_COMMAND);
[p0] = R0;
[p0 + (ITEST_COMMAND - DTEST_COMMAND)] = R0;
CSYNC;
trace_buffer_init(p0,r0);
P0 = R1;
R0 = R1;
/* Turn off the icache */
p0.l = LO(IMEM_CONTROL);
p0.h = HI(IMEM_CONTROL);
R1 = [p0];
R0 = ~ENICPLB;
R0 = R0 & R1;
[p0] = R0;
SSYNC;
/* Turn off the dcache */
p0.l = LO(DMEM_CONTROL);
p0.h = HI(DMEM_CONTROL);
R1 = [p0];
R0 = ~ENDCPLB;
R0 = R0 & R1;
[p0] = R0;
SSYNC;
/* in case of double faults, save a few things */
p0.l = _init_retx;
p0.h = _init_retx;
R0 = RETX;
[P0] = R0;
#ifdef CONFIG_DEBUG_DOUBLEFAULT
/* Only save these if we are storing them,
* This happens here, since L1 gets clobbered
* below
*/
GET_PDA(p0, r0);
r6 = [p0 + PDA_DF_RETX];
p1.l = _init_saved_retx;
p1.h = _init_saved_retx;
[p1] = r6;
r6 = [p0 + PDA_DF_DCPLB];
p1.l = _init_saved_dcplb_fault_addr;
p1.h = _init_saved_dcplb_fault_addr;
[p1] = r6;
r6 = [p0 + PDA_DF_ICPLB];
p1.l = _init_saved_icplb_fault_addr;
p1.h = _init_saved_icplb_fault_addr;
[p1] = r6;
r6 = [p0 + PDA_DF_SEQSTAT];
p1.l = _init_saved_seqstat;
p1.h = _init_saved_seqstat;
[p1] = r6;
#endif
/* Initialize stack pointer */
sp.l = _init_thread_union;
sp.h = _init_thread_union;
fp = sp;
usp = sp;
#ifdef CONFIG_EARLY_PRINTK
call _init_early_exception_vectors;
r0 = (EVT_IVHW | EVT_IRPTEN | EVT_EVX | EVT_NMI | EVT_RST | EVT_EMU);
sti r0;
#endif
r0 = 0 (x);
/* Zero out all of the fun bss regions */
#if L1_DATA_A_LENGTH > 0
r1.l = __sbss_l1;
r1.h = __sbss_l1;
r2.l = __ebss_l1;
r2.h = __ebss_l1;
call __init_clear_bss
#endif
#if L1_DATA_B_LENGTH > 0
r1.l = __sbss_b_l1;
r1.h = __sbss_b_l1;
r2.l = __ebss_b_l1;
r2.h = __ebss_b_l1;
call __init_clear_bss
#endif
#if L2_LENGTH > 0
r1.l = __sbss_l2;
r1.h = __sbss_l2;
r2.l = __ebss_l2;
r2.h = __ebss_l2;
call __init_clear_bss
#endif
r1.l = ___bss_start;
r1.h = ___bss_start;
r2.l = ___bss_stop;
r2.h = ___bss_stop;
call __init_clear_bss
/* Put The Code for PLL Programming and SDRAM Programming in L1 ISRAM */
call _bfin_relocate_l1_mem;
#ifdef CONFIG_BFIN_KERNEL_CLOCK
/* Only use on-chip scratch space for stack when absolutely required
* to avoid Anomaly 05000227 ... we know the init_clocks() func only
* uses L1 text and stack space and no other memory region.
*/
# define KERNEL_CLOCK_STACK (L1_SCRATCH_START + L1_SCRATCH_LENGTH - 12)
sp.l = lo(KERNEL_CLOCK_STACK);
sp.h = hi(KERNEL_CLOCK_STACK);
call _init_clocks;
sp = usp; /* usp hasnt been touched, so restore from there */
#endif
/* This section keeps the processor in supervisor mode
* during kernel boot. Switches to user mode at end of boot.
* See page 3-9 of Hardware Reference manual for documentation.
*/
/* EVT15 = _real_start */
p0.l = lo(EVT15);
p0.h = hi(EVT15);
p1.l = _real_start;
p1.h = _real_start;
[p0] = p1;
csync;
#ifdef CONFIG_EARLY_PRINTK
r0 = (EVT_IVG15 | EVT_IVHW | EVT_IRPTEN | EVT_EVX | EVT_NMI | EVT_RST | EVT_EMU) (z);
#else
r0 = EVT_IVG15 (z);
#endif
sti r0;
raise 15;
#ifdef CONFIG_EARLY_PRINTK
p0.l = _early_trap;
p0.h = _early_trap;
#else
p0.l = .LWAIT_HERE;
p0.h = .LWAIT_HERE;
#endif
reti = p0;
#if ANOMALY_05000281
nop; nop; nop;
#endif
rti;
.LWAIT_HERE:
jump .LWAIT_HERE;
ENDPROC(__start)
/* A little BF561 glue ... */
#ifndef WDOG_CTL
# define WDOG_CTL WDOGA_CTL
#endif
ENTRY(_real_start)
/* Enable nested interrupts */
[--sp] = reti;
/* watchdog off for now */
p0.l = lo(WDOG_CTL);
p0.h = hi(WDOG_CTL);
r0 = 0xAD6(z);
w[p0] = r0;
ssync;
/* Pass the u-boot arguments to the global value command line */
R0 = R7;
call _cmdline_init;
/* Load the current thread pointer and stack */
p1 = THREAD_SIZE + 4 (z); /* +4 is for reti loading */
sp = sp + p1;
usp = sp;
fp = sp;
sp += -12;
call _init_pda
sp += 12;
jump.l _start_kernel;
ENDPROC(_real_start)
__FINIT