[PATCH 05/13] Split FDPIC "struct elf_prstatus" to "struct elf_fdpic_prstatus"

Palmer Dabbelt
2015-11-03T19:51:08Z

This is a pretty big change that I haven't tested any, which worries
me a lot. The general idea here is that "struct elf_prstatus" can be
visible to userspace (from <linux/ptrace.h>)

"
Generic ptrace interface that exports the architecture specific
regsets using the corresponding NT_* types (which are also used in
the core dump). Please note that the NT_PRSTATUS note type in a
core dump contains a full 'struct elf_prstatus'. But the
user_regset for NT_PRSTATUS contains just the elf_gregset_t that is
the pr_reg field of 'struct elf_prstatus'. For all the other
user_regset flavors, the user_regset layout and the ELF core dump
note payload are exactly the same layout.
"

so it shouldn't have an "#ifdef CONFIG_" in there.

This splits the structure into two different structures, one still
named "struct elf_prstatus", and one for ELF FDPIC that is named
"struct elf_fdpic_prstatus" -- the idea here is that most users are
standard ELF, so that's the name that didn't change.

I tried to fix all the users of "struct elf_prstatus" that should now
be using "struct elf_fdpic_prstatus". The only testing I did here was
to build a Blackfin defconfig with "struct elf_prstatus" not defined,
and to build an x86 defconfig with "struct elf_fdpic_prstatus" not
defined.

Note that this fails checkpatch.pl with a complaint about wanting open
braces on the same line as struct definitions. The existing struct
definitions in this file have the brace a line afterwards, so I'm
going to leave this alone.

Signed-off-by: Palmer Dabbelt <palmer@dabbelt.com>
Reviewed-by: Andrew Waterman <waterman@eecs.berkeley.edu>
Reviewed-by: Albert Ou <aou@eecs.berkeley.edu>
---
fs/binfmt_elf_fdpic.c | 6 +++---
fs/proc/kcore.c | 16 ++++++++++++++++
include/linux/kexec.h | 4 ++++
include/uapi/linux/elfcore.h | 37 +++++++++++++++++++++++++++++++++++--
kernel/kexec_core.c | 4 ++++
5 files changed, 62 insertions(+), 5 deletions(-)

diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c
index d3634bf..587bf04 100644
--- a/fs/binfmt_elf_fdpic.c
+++ b/fs/binfmt_elf_fdpic.c
@@ -1323,7 +1323,7 @@ static inline void fill_note(struct memelfnote *note, const char *name, int type
* fill up all the fields in prstatus from the given task struct, except
* registers which need to be filled up separately.
*/
-static void fill_prstatus(struct elf_prstatus *prstatus,
+static void fill_prstatus(struct elf_fdpic_prstatus *prstatus,
struct task_struct *p, long signr)
{
prstatus->pr_info.si_signo = prstatus->pr_cursig = signr;
@@ -1406,7 +1406,7 @@ static int fill_psinfo(struct elf_prpsinfo *psinfo, struct task_struct *p,
struct elf_thread_status
{
struct list_head list;
- struct elf_prstatus prstatus; /* NT_PRSTATUS */
+ struct elf_fdpic_prstatus prstatus; /* NT_PRSTATUS */
elf_fpregset_t fpu; /* NT_PRFPREG */
struct task_struct *thread;
#ifdef ELF_CORE_COPY_XFPREGS
@@ -1539,7 +1539,7 @@ static int elf_fdpic_core_dump(struct coredump_params *cprm)
loff_t offset = 0, dataoff;
int numnote;
struct memelfnote *notes = NULL;
- struct elf_prstatus *prstatus = NULL; /* NT_PRSTATUS */
+ struct elf_fdpic_prstatus *prstatus = NULL; /* NT_PRSTATUS */
struct elf_prpsinfo *psinfo = NULL; /* NT_PRPSINFO */
LIST_HEAD(thread_list);
struct list_head *t;
diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c
index 92e6726..b1edd77e 100644
--- a/fs/proc/kcore.c
+++ b/fs/proc/kcore.c
@@ -90,7 +90,11 @@ static size_t get_kcore_size(int *nphdr, size_t *elf_buflen)
(*nphdr + 2)*sizeof(struct elf_phdr) +
3 * ((sizeof(struct elf_note)) +
roundup(sizeof(CORE_STR), 4)) +
+#ifdef CONFIG_BINFMT_ELF_FDPIC
+ roundup(sizeof(struct elf_fdpic_prstatus), 4) +
+#else
roundup(sizeof(struct elf_prstatus), 4) +
+#endif
roundup(sizeof(struct elf_prpsinfo), 4) +
roundup(arch_task_struct_size, 4);
*elf_buflen = PAGE_ALIGN(*elf_buflen);
@@ -318,7 +322,11 @@ static char *storenote(struct memelfnote *men, char *bufp)
*/
static void elf_kcore_store_hdr(char *bufp, int nphdr, int dataoff)
{
+#ifdef CONFIG_BINFMT_ELF_FDPIC
+ struct elf_fdpic_prstatus prstatus; /* NT_PRSTATUS */
+#else
struct elf_prstatus prstatus; /* NT_PRSTATUS */
+#endif
struct elf_prpsinfo prpsinfo; /* NT_PRPSINFO */
struct elf_phdr *nhdr, *phdr;
struct elfhdr *elf;
@@ -387,10 +395,18 @@ static void elf_kcore_store_hdr(char *bufp, int nphdr, int dataoff)
/* set up the process status */
notes[0].name = CORE_STR;
notes[0].type = NT_PRSTATUS;
+#ifdef CONFIG_BINFMT_ELF_FDPIC
+ notes[0].datasz = sizeof(struct elf_fdpic_prstatus);
+#else
notes[0].datasz = sizeof(struct elf_prstatus);
+#endif
notes[0].data = &prstatus;

+#ifdef CONFIG_BINFMT_ELF_FDPIC
+ memset(&prstatus, 0, sizeof(struct elf_fdpic_prstatus));
+#else
memset(&prstatus, 0, sizeof(struct elf_prstatus));
+#endif

nhdr->p_filesz = notesize(&notes[0]);
bufp = storenote(&notes[0], bufp);
diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index d140b1e..d9196cc 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -63,7 +63,11 @@
#define KEXEC_NOTE_HEAD_BYTES ALIGN(sizeof(struct elf_note), 4)
#define KEXEC_CORE_NOTE_NAME "CORE"
#define KEXEC_CORE_NOTE_NAME_BYTES ALIGN(sizeof(KEXEC_CORE_NOTE_NAME), 4)
+#ifdef CONFIG_BINFMT_ELF_FDPIC
+#define KEXEC_CORE_NOTE_DESC_BYTES ALIGN(sizeof(struct elf_fdpic_prstatus), 4)
+#else
#define KEXEC_CORE_NOTE_DESC_BYTES ALIGN(sizeof(struct elf_prstatus), 4)
+#endif
/*
* The per-cpu notes area is a list of notes terminated by a "NULL"
* note header. For kdump, the code in vmcore.c runs in the context
diff --git a/include/uapi/linux/elfcore.h b/include/uapi/linux/elfcore.h
index 569737c..697c52d 100644
--- a/include/uapi/linux/elfcore.h
+++ b/include/uapi/linux/elfcore.h
@@ -60,7 +60,40 @@ struct elf_prstatus
long pr_instr; /* Current instruction */
#endif
elf_gregset_t pr_reg; /* GP registers */
-#ifdef CONFIG_BINFMT_ELF_FDPIC
+ int pr_fpvalid; /* True if math co-processor being used. */
+};
+
+/* Architectures that set CONFIG_BINFMT_ELF_FDPIC use this instead of
+ * "struct elf_prstatus".
+ */
+struct elf_fdpic_prstatus
+{
+#if 0
+ long pr_flags; /* XXX Process flags */
+ short pr_why; /* XXX Reason for process halt */
+ short pr_what; /* XXX More detailed reason */
+#endif
+ struct elf_siginfo pr_info; /* Info associated with signal */
+ short pr_cursig; /* Current signal */
+ unsigned long pr_sigpend; /* Set of pending signals */
+ unsigned long pr_sighold; /* Set of held signals */
+#if 0
+ struct sigaltstack pr_altstack; /* Alternate stack info */
+ struct sigaction pr_action; /* Signal action for current sig */
+#endif
+ pid_t pr_pid;
+ pid_t pr_ppid;
+ pid_t pr_pgrp;
+ pid_t pr_sid;
+ struct timeval pr_utime; /* User time */
+ struct timeval pr_stime; /* System time */
+ struct timeval pr_cutime; /* Cumulative user time */
+ struct timeval pr_cstime; /* Cumulative system time */
+#if 0
+ long pr_instr; /* Current instruction */
+#endif
+ elf_gregset_t pr_reg; /* GP registers */
+
/* When using FDPIC, the loadmap addresses need to be communicated
* to GDB in order for GDB to do the necessary relocations. The
* fields (below) used to communicate this information are placed
@@ -69,7 +102,7 @@ struct elf_prstatus
*/
unsigned long pr_exec_fdpic_loadmap;
unsigned long pr_interp_fdpic_loadmap;
-#endif
+
int pr_fpvalid; /* True if math co-processor being used. */
};

diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index 201b453..8d2fc70 100644
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -977,7 +977,11 @@ static void final_note(u32 *buf)

void crash_save_cpu(struct pt_regs *regs, int cpu)
{
+#ifdef CONFIG_BINFMT_ELF_FDPIC
+ struct elf_fdpic_prstatus prstatus;
+#else
struct elf_prstatus prstatus;
+#endif
u32 *buf;

if ((cpu < 0) || (cpu >= nr_cpu_ids))
--
2.4.10