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 <mahesh@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

4 files changed, 365 insertions, 2 deletions

diff --git a/arch/powerpc/include/asm/fadump.h b/arch/powerpc/include/asm/fadump.h
index 9e172a5d53c..67681958e4b 100644
--- a/arch/powerpc/include/asm/fadump.h
+++ b/arch/powerpc/include/asm/fadump.h
@@ -65,6 +65,18 @@
 /* Dump status flag */
 #define FADUMP_ERROR_FLAG       0x2000
 
+#define FADUMP_CPU_ID_MASK      ((1UL << 32) - 1)
+
+#define CPU_UNKNOWN             (~((u32)0))
+
+/* Utility macros */
+#define SKIP_TO_NEXT_CPU(reg_entry)                     \
+({                                                      \
+        while (reg_entry->reg_id != REG_ID("CPUEND"))   \
+                reg_entry++;                            \
+        reg_entry++;                                    \
+})
+
 /* Kernel Dump section info */
 struct fadump_section {
         u32     request_flag;
@@ -119,6 +131,9 @@ struct fw_dump {
         unsigned long   reserve_bootvar;
 
         unsigned long   fadumphdr_addr;
+        unsigned long   cpu_notes_buf;
+        unsigned long   cpu_notes_buf_size;
+
         int             ibm_configure_kernel_dump;
 
         unsigned long   fadump_enabled:1;
@@ -143,13 +158,40 @@ static inline u64 str_to_u64(const char *str)
         return val;
 }
 #define STR_TO_HEX(x)   str_to_u64(x)
+#define REG_ID(x)       str_to_u64(x)
 
 #define FADUMP_CRASH_INFO_MAGIC         STR_TO_HEX("FADMPINF")
+#define REGSAVE_AREA_MAGIC              STR_TO_HEX("REGSAVE")
+
+/* The firmware-assisted dump format.
+ *
+ * The register save area is an area in the partition's memory used to preserve
+ * the register contents (CPU state data) for the active CPUs during a firmware
+ * assisted dump. The dump format contains register save area header followed
+ * by register entries. Each list of registers for a CPU starts with
+ * "CPUSTRT" and ends with "CPUEND".
+ */
+
+/* Register save area header. */
+struct fadump_reg_save_area_header {
+        u64             magic_number;
+        u32             version;
+        u32             num_cpu_offset;
+};
+
+/* Register entry. */
+struct fadump_reg_entry {
+        u64             reg_id;
+        u64             reg_value;
+};
 
 /* fadump crash info structure */
 struct fadump_crash_info_header {
         u64             magic_number;
         u64             elfcorehdr_addr;
+        u32             crashing_cpu;
+        struct pt_regs  regs;
+        struct cpumask  cpu_online_mask;
 };
 
 /* Crash memory ranges */
@@ -165,7 +207,9 @@ extern int early_init_dt_scan_fw_dump(unsigned long node,
 extern int fadump_reserve_mem(void);
 extern int setup_fadump(void);
 extern int is_fadump_active(void);
+extern void crash_fadump(struct pt_regs *, const char *);
 #else   /* CONFIG_FA_DUMP */
 static inline int is_fadump_active(void) { return 0; }
+static inline void crash_fadump(struct pt_regs *regs, const char *str) { }
 #endif
 #endif
diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
index 63857e183de..da68bdad194 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, &note, 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, &note, 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, &regs);
+                        SKIP_TO_NEXT_CPU(reg_entry);
+                } else {
+                        reg_entry++;
+                        reg_entry = fadump_read_registers(reg_entry, &regs);
+                        note_buf = fadump_regs_to_elf_notes(note_buf, &regs);
+                }
+        }
+        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;
 }
diff --git a/arch/powerpc/kernel/setup-common.c b/arch/powerpc/kernel/setup-common.c
index 77bb77da05c..4e62a56e1a9 100644
--- a/arch/powerpc/kernel/setup-common.c
+++ b/arch/powerpc/kernel/setup-common.c
@@ -61,6 +61,7 @@
 #include <asm/xmon.h>
 #include <asm/cputhreads.h>
 #include <mm/mmu_decl.h>
+#include <asm/fadump.h>
 
 #include "setup.h"
 
@@ -639,6 +640,11 @@ EXPORT_SYMBOL(check_legacy_ioport);
 static int ppc_panic_event(struct notifier_block *this,
                              unsigned long event, void *ptr)
 {
+        /*
+         * If firmware-assisted dump has been registered then trigger
+         * firmware-assisted dump and let firmware handle everything else.
+         */
+        crash_fadump(NULL, ptr);
         ppc_md.panic(ptr);  /* May not return */
         return NOTIFY_DONE;
 }
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index c091527efd8..5d40e592ffc 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -57,6 +57,7 @@
 #include <asm/kexec.h>
 #include <asm/ppc-opcode.h>
 #include <asm/rio.h>
+#include <asm/fadump.h>
 
 #if defined(CONFIG_DEBUGGER) || defined(CONFIG_KEXEC)
 int (*__debugger)(struct pt_regs *regs) __read_mostly;
@@ -145,6 +146,8 @@ static void __kprobes oops_end(unsigned long flags, struct pt_regs *regs,
                 arch_spin_unlock(&die_lock);
         raw_local_irq_restore(flags);
 
+        crash_fadump(regs, "die oops");
+
         /*
          * A system reset (0x100) is a request to dump, so we always send
          * it through the crashdump code.