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>
This commit is contained in:
Al Viro 2020-06-01 19:42:40 -04:00
parent b3a9e3b962
commit b4e9c9549f
4 changed files with 90 additions and 29 deletions

View File

@ -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);
@ -1846,33 +1848,29 @@ 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];
do_thread_regset_writeback(t->task, regset);
if (regset->core_note_type && regset->get &&
(!regset->active || regset->active(t->task, regset) > 0)) {
int note_type = regset->core_note_type;
bool is_fpreg = note_type == NT_PRFPREG;
void *data;
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);
}
do_thread_regset_writeback(t->task, regset);
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;
}

View File

@ -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

View File

@ -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

54
kernel/regset.c Normal file
View File

@ -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);