From ebaeb5ae24379b5b635dc1d1fa6df904bc95b4d9 Mon Sep 17 00:00:00 2001 From: Mahesh Salgaonkar Date: Thu, 16 Feb 2012 01:14:45 +0000 Subject: fadump: Convert firmware-assisted cpu state dump data into elf notes. When registered for firmware assisted dump on powerpc, firmware preserves the registers for the active CPUs during a system crash. This patch reads the cpu register data stored in Firmware-assisted dump format (except for crashing cpu) and converts it into elf notes and updates the PT_NOTE program header accordingly. The exact register state for crashing cpu is saved to fadump crash info structure in scratch area during crash_fadump() and read during second kernel boot. Signed-off-by: Mahesh Salgaonkar Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/kernel/fadump.c | 314 ++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 312 insertions(+), 2 deletions(-) (limited to 'arch/powerpc/kernel/fadump.c') diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c index 63857e183de5..da68bdad194a 100644 --- a/arch/powerpc/kernel/fadump.c +++ b/arch/powerpc/kernel/fadump.c @@ -240,6 +240,7 @@ static unsigned long get_fadump_area_size(void) size += fw_dump.boot_memory_size; size += sizeof(struct fadump_crash_info_header); size += sizeof(struct elfhdr); /* ELF core header.*/ + size += sizeof(struct elf_phdr); /* place holder for cpu notes */ /* Program headers for crash memory regions. */ size += sizeof(struct elf_phdr) * (memblock_num_regions(memory) + 2); @@ -393,6 +394,285 @@ static void register_fw_dump(struct fadump_mem_struct *fdm) } } +void crash_fadump(struct pt_regs *regs, const char *str) +{ + struct fadump_crash_info_header *fdh = NULL; + + if (!fw_dump.dump_registered || !fw_dump.fadumphdr_addr) + return; + + fdh = __va(fw_dump.fadumphdr_addr); + crashing_cpu = smp_processor_id(); + fdh->crashing_cpu = crashing_cpu; + crash_save_vmcoreinfo(); + + if (regs) + fdh->regs = *regs; + else + ppc_save_regs(&fdh->regs); + + fdh->cpu_online_mask = *cpu_online_mask; + + /* Call ibm,os-term rtas call to trigger firmware assisted dump */ + rtas_os_term((char *)str); +} + +#define GPR_MASK 0xffffff0000000000 +static inline int fadump_gpr_index(u64 id) +{ + int i = -1; + char str[3]; + + if ((id & GPR_MASK) == REG_ID("GPR")) { + /* get the digits at the end */ + id &= ~GPR_MASK; + id >>= 24; + str[2] = '\0'; + str[1] = id & 0xff; + str[0] = (id >> 8) & 0xff; + sscanf(str, "%d", &i); + if (i > 31) + i = -1; + } + return i; +} + +static inline void fadump_set_regval(struct pt_regs *regs, u64 reg_id, + u64 reg_val) +{ + int i; + + i = fadump_gpr_index(reg_id); + if (i >= 0) + regs->gpr[i] = (unsigned long)reg_val; + else if (reg_id == REG_ID("NIA")) + regs->nip = (unsigned long)reg_val; + else if (reg_id == REG_ID("MSR")) + regs->msr = (unsigned long)reg_val; + else if (reg_id == REG_ID("CTR")) + regs->ctr = (unsigned long)reg_val; + else if (reg_id == REG_ID("LR")) + regs->link = (unsigned long)reg_val; + else if (reg_id == REG_ID("XER")) + regs->xer = (unsigned long)reg_val; + else if (reg_id == REG_ID("CR")) + regs->ccr = (unsigned long)reg_val; + else if (reg_id == REG_ID("DAR")) + regs->dar = (unsigned long)reg_val; + else if (reg_id == REG_ID("DSISR")) + regs->dsisr = (unsigned long)reg_val; +} + +static struct fadump_reg_entry* +fadump_read_registers(struct fadump_reg_entry *reg_entry, struct pt_regs *regs) +{ + memset(regs, 0, sizeof(struct pt_regs)); + + while (reg_entry->reg_id != REG_ID("CPUEND")) { + fadump_set_regval(regs, reg_entry->reg_id, + reg_entry->reg_value); + reg_entry++; + } + reg_entry++; + return reg_entry; +} + +static u32 *fadump_append_elf_note(u32 *buf, char *name, unsigned type, + void *data, size_t data_len) +{ + struct elf_note note; + + note.n_namesz = strlen(name) + 1; + note.n_descsz = data_len; + note.n_type = type; + memcpy(buf, ¬e, sizeof(note)); + buf += (sizeof(note) + 3)/4; + memcpy(buf, name, note.n_namesz); + buf += (note.n_namesz + 3)/4; + memcpy(buf, data, note.n_descsz); + buf += (note.n_descsz + 3)/4; + + return buf; +} + +static void fadump_final_note(u32 *buf) +{ + struct elf_note note; + + note.n_namesz = 0; + note.n_descsz = 0; + note.n_type = 0; + memcpy(buf, ¬e, sizeof(note)); +} + +static u32 *fadump_regs_to_elf_notes(u32 *buf, struct pt_regs *regs) +{ + struct elf_prstatus prstatus; + + memset(&prstatus, 0, sizeof(prstatus)); + /* + * FIXME: How do i get PID? Do I really need it? + * prstatus.pr_pid = ???? + */ + elf_core_copy_kernel_regs(&prstatus.pr_reg, regs); + buf = fadump_append_elf_note(buf, KEXEC_CORE_NOTE_NAME, NT_PRSTATUS, + &prstatus, sizeof(prstatus)); + return buf; +} + +static void fadump_update_elfcore_header(char *bufp) +{ + struct elfhdr *elf; + struct elf_phdr *phdr; + + elf = (struct elfhdr *)bufp; + bufp += sizeof(struct elfhdr); + + /* First note is a place holder for cpu notes info. */ + phdr = (struct elf_phdr *)bufp; + + if (phdr->p_type == PT_NOTE) { + phdr->p_paddr = fw_dump.cpu_notes_buf; + phdr->p_offset = phdr->p_paddr; + phdr->p_filesz = fw_dump.cpu_notes_buf_size; + phdr->p_memsz = fw_dump.cpu_notes_buf_size; + } + return; +} + +static void *fadump_cpu_notes_buf_alloc(unsigned long size) +{ + void *vaddr; + struct page *page; + unsigned long order, count, i; + + order = get_order(size); + vaddr = (void *)__get_free_pages(GFP_KERNEL|__GFP_ZERO, order); + if (!vaddr) + return NULL; + + count = 1 << order; + page = virt_to_page(vaddr); + for (i = 0; i < count; i++) + SetPageReserved(page + i); + return vaddr; +} + +static void fadump_cpu_notes_buf_free(unsigned long vaddr, unsigned long size) +{ + struct page *page; + unsigned long order, count, i; + + order = get_order(size); + count = 1 << order; + page = virt_to_page(vaddr); + for (i = 0; i < count; i++) + ClearPageReserved(page + i); + __free_pages(page, order); +} + +/* + * Read CPU state dump data and convert it into ELF notes. + * The CPU dump starts with magic number "REGSAVE". NumCpusOffset should be + * used to access the data to allow for additional fields to be added without + * affecting compatibility. Each list of registers for a CPU starts with + * "CPUSTRT" and ends with "CPUEND". Each register entry is of 16 bytes, + * 8 Byte ASCII identifier and 8 Byte register value. The register entry + * with identifier "CPUSTRT" and "CPUEND" contains 4 byte cpu id as part + * of register value. For more details refer to PAPR document. + * + * Only for the crashing cpu we ignore the CPU dump data and get exact + * state from fadump crash info structure populated by first kernel at the + * time of crash. + */ +static int __init fadump_build_cpu_notes(const struct fadump_mem_struct *fdm) +{ + struct fadump_reg_save_area_header *reg_header; + struct fadump_reg_entry *reg_entry; + struct fadump_crash_info_header *fdh = NULL; + void *vaddr; + unsigned long addr; + u32 num_cpus, *note_buf; + struct pt_regs regs; + int i, rc = 0, cpu = 0; + + if (!fdm->cpu_state_data.bytes_dumped) + return -EINVAL; + + addr = fdm->cpu_state_data.destination_address; + vaddr = __va(addr); + + reg_header = vaddr; + if (reg_header->magic_number != REGSAVE_AREA_MAGIC) { + printk(KERN_ERR "Unable to read register save area.\n"); + return -ENOENT; + } + pr_debug("--------CPU State Data------------\n"); + pr_debug("Magic Number: %llx\n", reg_header->magic_number); + pr_debug("NumCpuOffset: %x\n", reg_header->num_cpu_offset); + + vaddr += reg_header->num_cpu_offset; + num_cpus = *((u32 *)(vaddr)); + pr_debug("NumCpus : %u\n", num_cpus); + vaddr += sizeof(u32); + reg_entry = (struct fadump_reg_entry *)vaddr; + + /* Allocate buffer to hold cpu crash notes. */ + fw_dump.cpu_notes_buf_size = num_cpus * sizeof(note_buf_t); + fw_dump.cpu_notes_buf_size = PAGE_ALIGN(fw_dump.cpu_notes_buf_size); + note_buf = fadump_cpu_notes_buf_alloc(fw_dump.cpu_notes_buf_size); + if (!note_buf) { + printk(KERN_ERR "Failed to allocate 0x%lx bytes for " + "cpu notes buffer\n", fw_dump.cpu_notes_buf_size); + return -ENOMEM; + } + fw_dump.cpu_notes_buf = __pa(note_buf); + + pr_debug("Allocated buffer for cpu notes of size %ld at %p\n", + (num_cpus * sizeof(note_buf_t)), note_buf); + + if (fw_dump.fadumphdr_addr) + fdh = __va(fw_dump.fadumphdr_addr); + + for (i = 0; i < num_cpus; i++) { + if (reg_entry->reg_id != REG_ID("CPUSTRT")) { + printk(KERN_ERR "Unable to read CPU state data\n"); + rc = -ENOENT; + goto error_out; + } + /* Lower 4 bytes of reg_value contains logical cpu id */ + cpu = reg_entry->reg_value & FADUMP_CPU_ID_MASK; + if (!cpumask_test_cpu(cpu, &fdh->cpu_online_mask)) { + SKIP_TO_NEXT_CPU(reg_entry); + continue; + } + pr_debug("Reading register data for cpu %d...\n", cpu); + if (fdh && fdh->crashing_cpu == cpu) { + regs = fdh->regs; + note_buf = fadump_regs_to_elf_notes(note_buf, ®s); + SKIP_TO_NEXT_CPU(reg_entry); + } else { + reg_entry++; + reg_entry = fadump_read_registers(reg_entry, ®s); + note_buf = fadump_regs_to_elf_notes(note_buf, ®s); + } + } + fadump_final_note(note_buf); + + pr_debug("Updating elfcore header (%llx) with cpu notes\n", + fdh->elfcorehdr_addr); + fadump_update_elfcore_header((char *)__va(fdh->elfcorehdr_addr)); + return 0; + +error_out: + fadump_cpu_notes_buf_free((unsigned long)__va(fw_dump.cpu_notes_buf), + fw_dump.cpu_notes_buf_size); + fw_dump.cpu_notes_buf = 0; + fw_dump.cpu_notes_buf_size = 0; + return rc; + +} + /* * Validate and process the dump data stored by firmware before exporting * it through '/proc/vmcore'. @@ -400,18 +680,21 @@ static void register_fw_dump(struct fadump_mem_struct *fdm) static int __init process_fadump(const struct fadump_mem_struct *fdm_active) { struct fadump_crash_info_header *fdh; + int rc = 0; if (!fdm_active || !fw_dump.fadumphdr_addr) return -EINVAL; /* Check if the dump data is valid. */ if ((fdm_active->header.dump_status_flag == FADUMP_ERROR_FLAG) || + (fdm_active->cpu_state_data.error_flags != 0) || (fdm_active->rmr_region.error_flags != 0)) { printk(KERN_ERR "Dump taken by platform is not valid\n"); return -EINVAL; } - if (fdm_active->rmr_region.bytes_dumped != - fdm_active->rmr_region.source_len) { + if ((fdm_active->rmr_region.bytes_dumped != + fdm_active->rmr_region.source_len) || + !fdm_active->cpu_state_data.bytes_dumped) { printk(KERN_ERR "Dump taken by platform is incomplete\n"); return -EINVAL; } @@ -423,6 +706,10 @@ static int __init process_fadump(const struct fadump_mem_struct *fdm_active) return -EINVAL; } + rc = fadump_build_cpu_notes(fdm_active); + if (rc) + return rc; + /* * We are done validating dump info and elfcore header is now ready * to be exported. set elfcorehdr_addr so that vmcore module will @@ -537,6 +824,27 @@ static int fadump_create_elfcore_headers(char *bufp) elf = (struct elfhdr *)bufp; bufp += sizeof(struct elfhdr); + /* + * setup ELF PT_NOTE, place holder for cpu notes info. The notes info + * will be populated during second kernel boot after crash. Hence + * this PT_NOTE will always be the first elf note. + * + * NOTE: Any new ELF note addition should be placed after this note. + */ + phdr = (struct elf_phdr *)bufp; + bufp += sizeof(struct elf_phdr); + phdr->p_type = PT_NOTE; + phdr->p_flags = 0; + phdr->p_vaddr = 0; + phdr->p_align = 0; + + phdr->p_offset = 0; + phdr->p_paddr = 0; + phdr->p_filesz = 0; + phdr->p_memsz = 0; + + (elf->e_phnum)++; + /* setup PT_LOAD sections. */ for (i = 0; i < crash_mem_ranges; i++) { @@ -588,6 +896,8 @@ static unsigned long init_fadump_header(unsigned long addr) memset(fdh, 0, sizeof(struct fadump_crash_info_header)); fdh->magic_number = FADUMP_CRASH_INFO_MAGIC; fdh->elfcorehdr_addr = addr; + /* We will set the crashing cpu id in crash_fadump() during crash. */ + fdh->crashing_cpu = CPU_UNKNOWN; return addr; } -- cgit v1.2.3