From bc294838cc3443a2fbec58f8936ad4bd0a0b3055 Mon Sep 17 00:00:00 2001 From: Sven Schnelle Date: Thu, 14 Oct 2021 21:49:16 +0200 Subject: [PATCH] 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. 2800035d03e00000 0000000040c21ac8 CC_ERR_CHECK_TOC 2800035d00e00000 0000000040c21ad0 CC_ERR_CHECK_TOC 2800035d02e00000 0000000040c21ac8 CC_ERR_CHECK_TOC 2800035d01e00000 0000000040c21ad0 CC_ERR_CHECK_TOC 37000f7303e00000 2000000000000000 CC_ERR_CPU_CHECK_SUMMARY 37000f7300e00000 2000000000000000 CC_ERR_CPU_CHECK_SUMMARY 37000f7302e00000 2000000000000000 CC_ERR_CPU_CHECK_SUMMARY 37000f7301e00000 2000000000000000 CC_ERR_CPU_CHECK_SUMMARY 4300100803e00000 c0000000001d26cc CC_MC_BR_TO_OS_TOC 4300100800e00000 c0000000001d26cc CC_MC_BR_TO_OS_TOC 4300100802e00000 c0000000001d26cc CC_MC_BR_TO_OS_TOC 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 Signed-off-by: Helge Deller --- 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 906187a412ec..3296fcb90019 100644 --- a/arch/parisc/Kconfig +++ b/arch/parisc/Kconfig @@ -291,6 +291,20 @@ 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, say 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 290471ef5bac..f57944d3284b 100644 --- a/arch/parisc/include/asm/processor.h +++ b/arch/parisc/include/asm/processor.h @@ -295,6 +295,10 @@ 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 +#include +#include +#include +#include +#include + +#include +#include + +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 +#include +#include +#include + + .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)