introduction of regset ->get() wrappers, switching ELF coredumps to those

Two new helpers: given a process and regset, dump into a buffer.
regset_get() takes a buffer and size, regset_get_alloc() takes size
and allocates a buffer.

Return value in both cases is the amount of data actually dumped in
case of success or -E...  on error.

In both cases the size is capped by regset->n * regset->size, so
->get() is called with offset 0 and size no more than what regset
expects.

binfmt_elf.c callers of ->get() are switched to using those; the other
caller (copy_regset_to_user()) will need some preparations to switch.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 9fe3b51..e922a6a 100644 (file)
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1821,7 +1821,7 @@ static int fill_thread_core_info(struct elf_thread_core_info *t,
                                 long signr, size_t *total)
 {
        unsigned int i;
-       unsigned int regset0_size = regset_size(t->task, &view->regsets[0]);
+       int regset0_size;
 
        /*
         * NT_PRSTATUS is the one special case, because the regset data
@@ -1830,8 +1830,10 @@ static int fill_thread_core_info(struct elf_thread_core_info *t,
         * We assume that regset 0 is NT_PRSTATUS.
         */
        fill_prstatus(&t->prstatus, t->task, signr);
-       (void) view->regsets[0].get(t->task, &view->regsets[0], 0, regset0_size,
-                                   &t->prstatus.pr_reg, NULL);
+       regset0_size = regset_get(t->task, &view->regsets[0],
+                  sizeof(t->prstatus.pr_reg), &t->prstatus.pr_reg);
+       if (regset0_size < 0)
+               return 0;
 
        fill_note(&t->notes[0], "CORE", NT_PRSTATUS,
                  PRSTATUS_SIZE(t->prstatus, regset0_size), &t->prstatus);
@@ -1846,32 +1848,28 @@ static int fill_thread_core_info(struct elf_thread_core_info *t,
         */
        for (i = 1; i < view->n; ++i) {
                const struct user_regset *regset = &view->regsets[i];
+               int note_type = regset->core_note_type;
+               bool is_fpreg = note_type == NT_PRFPREG;
+               void *data;
+               int ret;
+
                do_thread_regset_writeback(t->task, regset);
-               if (regset->core_note_type && regset->get &&
-                   (!regset->active || regset->active(t->task, regset) > 0)) {
-                       int ret;
-                       size_t size = regset_size(t->task, regset);
-                       void *data = kzalloc(size, GFP_KERNEL);
-                       if (unlikely(!data))
-                               return 0;
-                       ret = regset->get(t->task, regset,
-                                         0, size, data, NULL);
-                       if (unlikely(ret))
-                               kfree(data);
-                       else {
-                               if (regset->core_note_type != NT_PRFPREG)
-                                       fill_note(&t->notes[i], "LINUX",
-                                                 regset->core_note_type,
-                                                 size, data);
-                               else {
-                                       SET_PR_FPVALID(&t->prstatus,
-                                                       1, regset0_size);
-                                       fill_note(&t->notes[i], "CORE",
-                                                 NT_PRFPREG, size, data);
-                               }
-                               *total += notesize(&t->notes[i]);
-                       }
-               }
+               if (!note_type) // not for coredumps
+                       continue;
+               if (regset->active && regset->active(t->task, regset) <= 0)
+                       continue;
+
+               ret = regset_get_alloc(t->task, regset, ~0U, &data);
+               if (ret < 0)
+                       continue;
+
+               if (is_fpreg)
+                       SET_PR_FPVALID(&t->prstatus, 1, regset0_size);
+
+               fill_note(&t->notes[i], is_fpreg ? "CORE" : "LINUX",
+                         note_type, ret, data);
+
+               *total += notesize(&t->notes[i]);
        }
 
        return 1;

diff --git a/include/linux/regset.h b/include/linux/regset.h
index 46d6ae6..968a032 100644 (file)
--- a/include/linux/regset.h
+++ b/include/linux/regset.h
@@ -353,6 +353,15 @@ static inline int user_regset_copyin_ignore(unsigned int *pos,
        return 0;
 }
 
+extern int regset_get(struct task_struct *target,
+                     const struct user_regset *regset,
+                     unsigned int size, void *data);
+
+extern int regset_get_alloc(struct task_struct *target,
+                           const struct user_regset *regset,
+                           unsigned int size,
+                           void **data);
+
 /**
  * copy_regset_to_user - fetch a thread's user_regset data into user memory
  * @target:    thread to be examined

diff --git a/kernel/Makefile b/kernel/Makefile
index f3218bc..e6e0338 100644 (file)
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -10,7 +10,7 @@ obj-y     = fork.o exec_domain.o panic.o \
            extable.o params.o \
            kthread.o sys_ni.o nsproxy.o \
            notifier.o ksysfs.o cred.o reboot.o \
-           async.o range.o smpboot.o ucount.o
+           async.o range.o smpboot.o ucount.o regset.o
 
 obj-$(CONFIG_MODULES) += kmod.o
 obj-$(CONFIG_MULTIUSER) += groups.o

diff --git a/kernel/regset.c b/kernel/regset.c
new file mode 100644 (file)
index 0000000..6b39fa0
--- /dev/null
+++ b/kernel/regset.c
@@ -0,0 +1,54 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/export.h>
+#include <linux/slab.h>
+#include <linux/regset.h>
+
+static int __regset_get(struct task_struct *target,
+                       const struct user_regset *regset,
+                       unsigned int size,
+                       void **data)
+{
+       void *p = *data, *to_free = NULL;
+       int res;
+
+       if (!regset->get)
+               return -EOPNOTSUPP;
+       if (size > regset->n * regset->size)
+               size = regset->n * regset->size;
+       if (!p) {
+               to_free = p = kzalloc(size, GFP_KERNEL);
+               if (!p)
+                       return -ENOMEM;
+       }
+       res = regset->get(target, regset, 0, size, p, NULL);
+       if (unlikely(res < 0)) {
+               kfree(to_free);
+               return res;
+       }
+       *data = p;
+       if (regset->get_size) { // arm64-only kludge, will go away
+               unsigned max_size = regset->get_size(target, regset);
+               if (size > max_size)
+                       size = max_size;
+       }
+       return size;
+}
+
+int regset_get(struct task_struct *target,
+              const struct user_regset *regset,
+              unsigned int size,
+              void *data)
+{
+       return __regset_get(target, regset, size, &data);
+}
+EXPORT_SYMBOL(regset_get);
+
+int regset_get_alloc(struct task_struct *target,
+                    const struct user_regset *regset,
+                    unsigned int size,
+                    void **data)
+{
+       *data = NULL;
+       return __regset_get(target, regset, size, data);
+}
+EXPORT_SYMBOL(regset_get_alloc);