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>

1 files changed, 44 insertions, 0 deletions

diff --git a/arch/powerpc/include/asm/fadump.h b/arch/powerpc/include/asm/fadump.h
index 9e172a5d53c7..67681958e4b8 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