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@xxxxxxxxxxxxxx>
---
arch/parisc/Kconfig | 14 ++++
arch/parisc/include/asm/processor.h | 4 +
arch/parisc/include/uapi/asm/pdc.h | 6 +-
arch/parisc/kernel/Makefile | 1 +
arch/parisc/kernel/toc.c | 111 ++++++++++++++++++++++++++++
arch/parisc/kernel/toc_asm.S | 88 ++++++++++++++++++++++
6 files changed, 222 insertions(+), 2 deletions(-)
create mode 100644 arch/parisc/kernel/toc.c
create mode 100644 arch/parisc/kernel/toc_asm.S
diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig
index 27a8b49af11f..97a889eaffe1 100644
--- a/arch/parisc/Kconfig
+++ b/arch/parisc/Kconfig
@@ -288,6 +288,20 @@ config SMP
If you don't know what to do here, say N.
+config TOC
+ bool "Support TOC switch"
+ default y if 64BIT || !SMP
+ help
+ Most PA-RISC machines have either a switch at the back of the machine
+ or a command in BMC to trigger a TOC interrupt. If you say Y here a
+ handler will be installed which will either show a backtrace on all
+ CPUs, or enter a possible configured debugger like kgdb/kdb.
+
+ Note that with this option enabled, the kernel will use an additional 16KB
+ per possible CPU as a special stack for the TOC handler.
+
+ If you don't want to debug the Kernel, so N.
+
config PARISC_CPU_TOPOLOGY
bool "Support cpu topology definition"
depends on SMP
diff --git a/arch/parisc/include/asm/processor.h b/arch/parisc/include/asm/processor.h
index eeb7da064289..1e9a4c986921 100644
--- a/arch/parisc/include/asm/processor.h
+++ b/arch/parisc/include/asm/processor.h
@@ -294,6 +294,10 @@ extern int _parisc_requires_coherency;
extern int running_on_qemu;
+extern void toc_handler(void);
+extern unsigned int toc_handler_size;
+extern unsigned int toc_handler_csum;
+
#endif /* __ASSEMBLY__ */
#endif /* __ASM_PARISC_PROCESSOR_H */
diff --git a/arch/parisc/include/uapi/asm/pdc.h b/arch/parisc/include/uapi/asm/pdc.h
index ad51df8ba952..acc633c15722 100644
--- a/arch/parisc/include/uapi/asm/pdc.h
+++ b/arch/parisc/include/uapi/asm/pdc.h
@@ -398,8 +398,10 @@ struct zeropage {
/* int (*vec_rendz)(void); */
unsigned int vec_rendz;
int vec_pow_fail_flen;
- int vec_pad[10];
-
+ int vec_pad0[3];
+ unsigned int vec_toc_hi;
+ int vec_pad1[6];
+
/* [0x040] reserved processor dependent */
int pad0[112];
diff --git a/arch/parisc/kernel/Makefile b/arch/parisc/kernel/Makefile
index 068d90950d93..ed0b87908d71 100644
--- a/arch/parisc/kernel/Makefile
+++ b/arch/parisc/kernel/Makefile
@@ -39,3 +39,4 @@ obj-$(CONFIG_KGDB) += kgdb.o
obj-$(CONFIG_KPROBES) += kprobes.o
obj-$(CONFIG_KEXEC_CORE) += kexec.o relocate_kernel.o
obj-$(CONFIG_KEXEC_FILE) += kexec_file.o
+obj-$(CONFIG_TOC) += toc.o toc_asm.o
diff --git a/arch/parisc/kernel/toc.c b/arch/parisc/kernel/toc.c
new file mode 100644
index 000000000000..18327611cf8f
--- /dev/null
+++ b/arch/parisc/kernel/toc.c
@@ -0,0 +1,111 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/kernel.h>
+#include <linux/kgdb.h>
+#include <linux/printk.h>
+#include <linux/sched/debug.h>
+#include <linux/delay.h>
+#include <linux/reboot.h>
+
+#include <asm/pdc.h>
+#include <asm/pdc_chassis.h>
+
+unsigned int __aligned(16) toc_lock = 1;
+
+static void toc20_to_pt_regs(struct pt_regs *regs, struct pdc_toc_pim_20 *toc)
+{
+ int i;
+
+ regs->gr[0] = (unsigned long)toc->cr[22];
+
+ for (i = 1; i < 32; i++)
+ regs->gr[i] = (unsigned long)toc->gr[i];
+
+ for (i = 0; i < 8; i++)
+ regs->sr[i] = (unsigned long)toc->sr[i];
+
+ regs->iasq[0] = (unsigned long)toc->cr[17];
+ regs->iasq[1] = (unsigned long)toc->iasq_back;
+ regs->iaoq[0] = (unsigned long)toc->cr[18];
+ regs->iaoq[1] = (unsigned long)toc->iaoq_back;
+
+ regs->sar = (unsigned long)toc->cr[11];
+ regs->iir = (unsigned long)toc->cr[19];
+ regs->isr = (unsigned long)toc->cr[20];
+ regs->ior = (unsigned long)toc->cr[21];
+}
+
+static void toc11_to_pt_regs(struct pt_regs *regs, struct pdc_toc_pim_11 *toc)
+{
+ int i;
+
+ regs->gr[0] = toc->cr[22];
+
+ for (i = 1; i < 32; i++)
+ regs->gr[i] = toc->gr[i];
+
+ for (i = 0; i < 8; i++)
+ regs->sr[i] = toc->sr[i];
+
+ regs->iasq[0] = toc->cr[17];
+ regs->iasq[1] = toc->iasq_back;
+ regs->iaoq[0] = toc->cr[18];
+ regs->iaoq[1] = toc->iaoq_back;
+
+ regs->sar = toc->cr[11];
+ regs->iir = toc->cr[19];
+ regs->isr = toc->cr[20];
+ regs->ior = toc->cr[21];
+}
+
+void notrace __noreturn __cold toc_intr(struct pt_regs *regs)
+{
+ struct pdc_toc_pim_20 pim_data20;
+ struct pdc_toc_pim_11 pim_data11;
+
+ nmi_enter();
+
+ if (boot_cpu_data.cpu_type >= pcxu) {
+ if (pdc_pim_toc20(&pim_data20))
+ panic("Failed to get PIM data");
+ toc20_to_pt_regs(regs, &pim_data20);
+ } else {
+ if (pdc_pim_toc11(&pim_data11))
+ panic("Failed to get PIM data");
+ toc11_to_pt_regs(regs, &pim_data11);
+ }
+
+#ifdef CONFIG_KGDB
+ if (atomic_read(&kgdb_active) != -1)
+ kgdb_nmicallback(raw_smp_processor_id(), regs);
+ kgdb_handle_exception(9, SIGTRAP, 0, regs);
+#endif
+ show_regs(regs);
+
+ /* give other CPUs time to show their backtrace */
+ mdelay(2000);
+ machine_restart("TOC");
+
+ /* should never reach this */
+ panic("TOC");
+}
+
+static __init int setup_toc(void)
+{
+ unsigned int csum = 0;
+ unsigned long toc_code = (unsigned long)dereference_function_descriptor(toc_handler);
+ int i;
+
+ PAGE0->vec_toc = __pa(toc_code) & 0xffffffff;
+#ifdef CONFIG_64BIT
+ PAGE0->vec_toc_hi = __pa(toc_code) >> 32;
+#endif
+ PAGE0->vec_toclen = toc_handler_size;
+
+ for (i = 0; i < toc_handler_size/4; i++)
+ csum += ((u32 *)toc_code)[i];
+ toc_handler_csum = -csum;
+ pr_info("TOC handler registered\n");
+ return 0;
+}
+early_initcall(setup_toc);
diff --git a/arch/parisc/kernel/toc_asm.S b/arch/parisc/kernel/toc_asm.S
new file mode 100644
index 000000000000..e94ba8044190
--- /dev/null
+++ b/arch/parisc/kernel/toc_asm.S
@@ -0,0 +1,88 @@
+/* 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)
--
2.33.0
