[PATCH 13/33] Fetching thread specific Notes

Janani Venkataraman
2014-03-20T09:41:14Z

Populates prstatus for each and every thread of the task to be dumped by
accessing their respective /proc/tid/stat.

Fetching the required registers based on the architecture. The architectures
that are handled are X86, S390 and PPC.

We fetch the registers in thread-wise order, as some architectures depend on
the ordering of the notes. (e.g, s390)

Signed-off-by: Suzuki K. Poulose <suzuki@in.ibm.com>
Signed-off-by: Janani Venkataraman <jananive@linux.vnet.ibm.com>
---
src/coredump.h | 12 +++
src/elf-compat.h | 76 +++++++++++++++++++++
src/elf.c | 194 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
src/elf32.c | 1
src/elf64.c | 1
5 files changed, 283 insertions(+), 1 deletion(-)

diff --git a/src/coredump.h b/src/coredump.h
index d5562fe..dce6292 100644
--- a/src/coredump.h
+++ b/src/coredump.h
@@ -5,15 +5,27 @@
#define PGRP 1 /* Index for process group ID */
#define SID 2 /* Index for session ID */
#define FLAG 5 /* Index for flags */
+#define UTIME 10 /* Index for scheduled user mode */
+#define STIME 11 /* Index for scheduled user mode */
+#define CUTIME 12 /* Index for scheduled user mode time for a process's waited-for children */
+#define CSTIME 13 /* Index for scheduled kernel mode time for a process's waited-for children */
#define NICE 15 /* Index for nice value */
#define THREAD_COUNT_IDX 16 /* Index for number of threads */
+#define SIGPEND 27 /* Index for pending signals for a process */
+#define SIGHOLD 29 /* Index for ignored signals for a process */

#define __ps_thread_count ps_num[THREAD_COUNT_IDX] /* Process Information */
#define __ps_ppid ps_num[PPID] /* Process PID */
#define __ps_pgrp ps_num[PGRP] /* Process Group ID */
#define __ps_sid ps_num[SID] /* Process Session ID */
#define __ps_flag ps_num[FLAG] /* Process Flags */
+#define __ps_utime ps_num[UTIME] /* Process scheduled user mode */
+#define __ps_stime ps_num[STIME] /* Process scheduled user mode */
+#define __ps_cutime ps_num[CUTIME] /* Process scheduled user mode time for a process's waited-for children */
+#define __ps_cstime ps_num[CSTIME] /* Process scheduled kernel mode time for a process's waited-for children */
#define __ps_nice ps_num[NICE] /* Process Nice Value */
+#define __ps_sigpend ps_num[SIGPEND] /* Process pending signals */
+#define __ps_sighold ps_num[SIGHOLD] /* Process ignored signals */

/* Status of the dump */
extern int status;
diff --git a/src/elf-compat.h b/src/elf-compat.h
index 463070a..6399c11 100644
--- a/src/elf-compat.h
+++ b/src/elf-compat.h
@@ -33,6 +33,17 @@ typedef unsigned short compat_id;
typedef unsigned short compat_id;
#endif

+struct compat_elf_siginfo {
+ int si_signo;
+ int si_code;
+ int si_errno;
+};
+
+struct compat_timeval {
+ int tv_sec;
+ int tv_usec;
+};
+
/* Compat structure for PRPS_INFO */
struct compat_elf_prpsinfo {
char pr_state;
@@ -46,3 +57,68 @@ struct compat_elf_prpsinfo {
char pr_fname[16];
char pr_psargs[ELF_PRARGSZ];
};
+
+/* Power PC elf_gregset_t */
+#define ELF_NGREG_PPC 48
+typedef unsigned int elf_greg_t32_ppc;
+typedef elf_greg_t32_ppc elf_gregset_t32_ppc[ELF_NGREG_PPC];
+typedef elf_gregset_t32_ppc compat_elf_gregset_t_ppc;
+
+/* x86 elf_gregset_t */
+struct user_regs_struct32_x86 {
+ unsigned int ebx, ecx, edx, esi, edi, ebp, eax;
+ unsigned short ds, __ds, es, __es;
+ unsigned short fs, __fs, gs, __gs;
+ unsigned int orig_eax, eip;
+ unsigned short cs, __cs;
+ unsigned int eflags, esp;
+ unsigned short ss, __ss;
+};
+typedef struct user_regs_struct32_x86 compat_elf_gregset_t_x86;
+
+/* s390 elf_gregset_t */
+#define NUM_GPRS 16
+#define NUM_ACRS 16
+
+typedef struct {
+ unsigned int mask;
+ unsigned int addr;
+} __attribute__((aligned(8))) psw_compat_t;
+
+typedef struct {
+ psw_compat_t psw;
+ unsigned int gprs[NUM_GPRS];
+ unsigned int acrs[NUM_ACRS];
+ unsigned int orig_gpr2;
+} s390_compat_regs;
+
+typedef s390_compat_regs compat_elf_gregset_t_s390;
+
+#if defined(__PPC64__) || defined(__PPC__)
+#define compat_elf_gregset_t compat_elf_gregset_t_ppc
+#endif
+
+#if defined(__s390x__) || defined(__s390__)
+#define compat_elf_gregset_t compat_elf_gregset_t_s390
+#endif
+
+#if defined(__x86_64) || defined(__i386)
+#define compat_elf_gregset_t compat_elf_gregset_t_x86
+#endif
+
+struct compat_elf_prstatus {
+ struct compat_elf_siginfo pr_info;
+ short pr_cursig;
+ unsigned int pr_sigpend;
+ unsigned int pr_sighold;
+ int pr_pid;
+ int pr_ppid;
+ int pr_pgrp;
+ int pr_sid;
+ struct compat_timeval pr_utime;
+ struct compat_timeval pr_stime;
+ struct compat_timeval pr_cutime;
+ struct compat_timeval pr_cstime;
+ compat_elf_gregset_t pr_reg;
+ int pr_fpvalid;
+};
diff --git a/src/elf.c b/src/elf.c
index 9e3623f..62dc5a9 100644
--- a/src/elf.c
+++ b/src/elf.c
@@ -30,6 +30,7 @@
#include <unistd.h>
#include <sys/uio.h>
#include <sys/procfs.h>
+#include <sys/ptrace.h>
#include <linux/elf.h>
#include "elf-compat.h"
#include "coredump.h"
@@ -381,9 +382,195 @@ static int get_file_maps(struct core_proc *cp)
return ret;
}

-int do_elf_coredump(int pid, struct core_proc *cp)
+/* Getting Registers */
+static int get_regset(int tid, int regset, struct iovec *iov)
+{
+ return ptrace(PTRACE_GETREGSET, tid, regset, iov);
+}
+
+/* Fetching Note */
+static int fetch_note(int regset, const char *name, struct core_proc *cp, int tid)
+{
+ int ret = 0;
+ int size = PAGESIZE;
+ struct iovec iov;
+ void *data;
+ data = malloc(PAGESIZE);
+ if (!data)
+ return -1;
+
+ /*
+ * The size of regset being fetched may be greater than size,
+ * which is initially PAGESIZE. The iov_len gets reset to the
+ * amount of data read by PTRACE_GETREGSET. If the iov_len is
+ * equal to size, in that case, there is more data to read and
+ * hence we increase the size and try reading again. The moment
+ * iov.len is lesser than size, we break out of the loop as all
+ * the data is read
+ */
+ while (1) {
+ iov.iov_base = data;
+ iov.iov_len = size;
+ ret = get_regset(cp->t_id[tid], (unsigned int) regset,
+ &iov);
+ if (ret)
+ break;
+ if (iov.iov_len < size)
+ break;
+ size += PAGESIZE;
+ data = realloc(data, size);
+ if (!data)
+ return -1;
+ }
+
+ /* Adding Note */
+ if (ret == 0)
+ ret = add_note(name, regset, iov.iov_len, data, cp);
+
+ free(data);
+
+ return ret;
+}
+
+/* Populates PRSTATUS for the threads */
+static int fill_core_notes(int tid, struct core_proc *cp)
{
+ /* PRSTATUS */
+ struct iovec iov;
int ret;
+ struct Elf_prstatus prstat;
+ struct pid_stat p;
+ char state;
+
+ ret = get_pid_stat(cp->t_id[tid], &p);
+ if (ret)
+ return -1;
+
+ prstat.pr_pid = p.ps_pid;
+ prstat.pr_ppid = p.__ps_ppid;
+ prstat.pr_pgrp = p.__ps_pgrp;
+ prstat.pr_sid = p.__ps_sid;
+ prstat.pr_utime.tv_sec = p.__ps_utime;
+ prstat.pr_stime.tv_sec = p.__ps_stime;
+ prstat.pr_cutime.tv_sec = p.__ps_cutime;
+ prstat.pr_cstime.tv_sec = p.__ps_cstime;
+ prstat.pr_sigpend = p.__ps_sigpend;
+ prstat.pr_sighold = p.__ps_sighold;
+
+ /* General Purpose registers */
+ iov.iov_base = &prstat.pr_reg;
+ iov.iov_len = sizeof(prstat.pr_reg);
+ ret = get_regset(cp->t_id[tid], NT_PRSTATUS, &iov);
+ if (ret == -1) {
+ state = get_thread_status(cp->t_id[tid]);
+ if (state != 'Z') {
+ status = errno;
+ gencore_log("Failure in fetching General Purpose registers for Thread:%d.\n", tid);
+ return -1;
+ }
+ }
+
+ prstat.pr_info.si_signo = 0;
+
+ /* FP_REGSET */
+ ret = fetch_note(NT_PRFPREG, "CORE", cp, tid);
+ if ( ret == 0)
+ prstat.pr_fpvalid = 1;
+ else
+ prstat.pr_fpvalid = 0;
+
+ /* Adding PRSTATUS */
+ return add_note("CORE", NT_PRSTATUS, sizeof(prstat),
+ &prstat, cp);
+}
+
+/* X86 Specific Notes */
+static void fetch_x86_notes(struct core_proc *cp, int tid)
+{
+ int notes[] = {
+ NT_X86_XSTATE,
+ NT_386_TLS,
+ 0};
+ int i;
+
+ for (i = 0; notes[i]; i++)
+ (void)fetch_note(notes[i], "LINUX", cp, tid);
+}
+
+/* PPC Specific Notes */
+static void fetch_ppc_notes(struct core_proc *cp, int tid)
+{
+ int notes[] = {
+ NT_PPC_VMX,
+ NT_PPC_SPE,
+ NT_PPC_VSX,
+ 0};
+ int i;
+
+ for (i = 0; notes[i]; i++)
+ (void)fetch_note(notes[i], "LINUX", cp, tid);
+}
+
+/* S390 Specific Notes */
+static void fetch_s390_notes(struct core_proc *cp, int tid)
+{
+ int notes[] = {
+ NT_S390_HIGH_GPRS,
+ NT_S390_TIMER,
+ NT_S390_LAST_BREAK,
+ NT_S390_SYSTEM_CALL,
+ NT_S390_TODCMP,
+ NT_S390_TODPREG,
+ NT_S390_CTRS,
+ NT_S390_PREFIX,
+ 0};
+ int i;
+
+ for (i = 0; notes[i]; i++)
+ (void)fetch_note(notes[i], "LINUX", cp, tid);
+}
+
+/* Fetching thread specific notes */
+static int fetch_thread_notes(struct core_proc *cp)
+{
+ int tid, ret;
+
+ Elf_Ehdr *cp_elf;
+ cp_elf = (Elf_Ehdr *)cp->elf_hdr;
+
+ /*
+ * The architecture specific notes are optional and they may or may not
+ * be present. Hence we do not check if we were successful in fetching
+ * them or not.
+ */
+
+ for (tid = 0; tid < cp->thread_count; tid++) {
+ ret = fill_core_notes(tid, cp);
+ if (ret)
+ return -1;
+
+ switch (cp_elf->e_machine) {
+ case EM_X86_64:
+ case EM_386:
+ fetch_x86_notes(cp, tid);
+ break;
+ case EM_PPC:
+ case EM_PPC64:
+ fetch_ppc_notes(cp, tid);
+ break;
+ case EM_S390:
+ fetch_s390_notes(cp, tid);
+ break;
+ }
+
+ }
+
+ return 0;
+}
+
+int do_elf_coredump(int pid, struct core_proc *cp)
+{
+ int ret, i;

/* Fill ELF Header */
ret = fill_elf_header(pid, cp);
@@ -405,5 +592,10 @@ int do_elf_coredump(int pid, struct core_proc *cp)
if (ret)
return -1;

+ /* Get the thread specific notes */
+ ret = fetch_thread_notes(cp);
+ if (ret)
+ return -1;
+
return 0;
}
diff --git a/src/elf32.c b/src/elf32.c
index 0f7c03d..8ec287b 100644
--- a/src/elf32.c
+++ b/src/elf32.c
@@ -36,5 +36,6 @@
#define Elf_Nhdr Elf32_Nhdr
#define Elf_prpsinfo compat_elf_prpsinfo
#define Elf_Long int
+#define Elf_prstatus compat_elf_prstatus

#include "elf.c"
diff --git a/src/elf64.c b/src/elf64.c
index 77da222..780e2d4 100644
--- a/src/elf64.c
+++ b/src/elf64.c
@@ -36,5 +36,6 @@
#define Elf_Nhdr Elf64_Nhdr
#define Elf_prpsinfo elf_prpsinfo
#define Elf_Long long
+#define Elf_prstatus elf_prstatus

#include "elf.c"