linux/arch/parisc/kernel/toc_asm.S
Sven Schnelle bc294838cc parisc: add support for TOC (transfer of control)
Almost all PA-RISC machines have either a button that
is labeled with 'TOC' or a BMC function to trigger a TOC.
TOC is a non-maskable interrupt that is sent to the processor.
This can be used for diagnostic purposes like obtaining a
stack trace/register dump or to enter KDB/KGDB.

As an example, on my c8000, TOC can be used with:

CONFIG_KGDB=y
CONFIG_KGDB_KDB=y

and the 'kgdboc=ttyS0,115200' appended to the command line.

Press ^[( on serial console, which will enter the BMC command line,
and enter 'TOC s':

root@(none):/# (
cli>TOC s
Sending TOC/INIT.
<Cpu3> 2800035d03e00000  0000000040c21ac8  CC_ERR_CHECK_TOC
<Cpu0> 2800035d00e00000  0000000040c21ad0  CC_ERR_CHECK_TOC
<Cpu2> 2800035d02e00000  0000000040c21ac8  CC_ERR_CHECK_TOC
<Cpu1> 2800035d01e00000  0000000040c21ad0  CC_ERR_CHECK_TOC
<Cpu3> 37000f7303e00000  2000000000000000  CC_ERR_CPU_CHECK_SUMMARY
<Cpu0> 37000f7300e00000  2000000000000000  CC_ERR_CPU_CHECK_SUMMARY
<Cpu2> 37000f7302e00000  2000000000000000  CC_ERR_CPU_CHECK_SUMMARY
<Cpu1> 37000f7301e00000  2000000000000000  CC_ERR_CPU_CHECK_SUMMARY
<Cpu3> 4300100803e00000  c0000000001d26cc  CC_MC_BR_TO_OS_TOC
<Cpu0> 4300100800e00000  c0000000001d26cc  CC_MC_BR_TO_OS_TOC
<Cpu2> 4300100802e00000  c0000000001d26cc  CC_MC_BR_TO_OS_TOC
<Cpu1> 4300100801e00000  c0000000001d26cc  CC_MC_BR_TO_OS_TOC

Entering kdb (current=0x00000000411cef80, pid 0) on processor 0 due to NonMaskable Interrupt @ 0x40c21ad0
[0]kdb>

Signed-off-by: Sven Schnelle <svens@stackframe.org>
Signed-off-by: Helge Deller <deller@gmx.de>
2021-11-01 07:35:59 +01:00

89 lines
1.6 KiB
ArmAsm

/* SPDX-License-Identifier: GPL-2.0-or-later */
/* TOC (Transfer of Control) handler. */
.level 1.1
#include <asm/assembly.h>
#include <asm/psw.h>
#include <linux/threads.h>
#include <linux/linkage.h>
.text
.import toc_intr,code
.import toc_lock,data
.align 16
ENTRY_CFI(toc_handler)
/*
* synchronize CPUs and obtain offset
* for stack setup.
*/
load32 PA(toc_lock),%r1
0: ldcw,co 0(%r1),%r2
cmpib,= 0,%r2,0b
nop
addi 1,%r2,%r4
stw %r4,0(%r1)
addi -1,%r2,%r4
load32 PA(toc_stack),%sp
/*
* deposit CPU number into stack address,
* so every CPU will have its own stack.
*/
SHLREG %r4,14,%r4
add %r4,%sp,%sp
/*
* setup pt_regs on stack and save the
* floating point registers. PIM_TOC doesn't
* save fp registers, so we're doing it here.
*/
copy %sp,%arg0
ldo PT_SZ_ALGN(%sp), %sp
/* clear pt_regs */
copy %arg0,%r1
0: cmpb,<<,n %r1,%sp,0b
stw,ma %r0,4(%r1)
ldo PT_FR0(%arg0),%r25
save_fp %r25
/* go virtual */
load32 PA(swapper_pg_dir),%r4
mtctl %r4,%cr24
mtctl %r4,%cr25
/* Clear sr4-sr7 */
mtsp %r0, %sr4
mtsp %r0, %sr5
mtsp %r0, %sr6
mtsp %r0, %sr7
tovirt_r1 %sp
tovirt_r1 %arg0
virt_map
loadgp
#ifdef CONFIG_64BIT
ldo -16(%sp),%r29
#endif
load32 toc_intr,%r1
be 0(%sr7,%r1)
nop
ENDPROC_CFI(toc_handler)
/*
* keep this checksum here, as it is part of the toc_handler
* spanned by toc_handler_size (all words in toc_handler are
* added in PDC and the sum must equal to zero.
*/
SYM_DATA(toc_handler_csum, .long 0)
SYM_DATA(toc_handler_size, .long . - toc_handler)
__PAGE_ALIGNED_BSS
.align 64
SYM_DATA(toc_stack, .block 16384*NR_CPUS)