Commit b4e9c954 authored by Al Viro's avatar Al Viro
Browse files

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: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent b3a9e3b9

fs/binfmt_elf.c

+26 −28
Original line number Diff line number Diff line
@@ -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;

}

include/linux/regset.h

+9 −0
Original line number Diff line number Diff line
@@ -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

kernel/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -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

kernel/regset.c

0 → 100644
+54 −0
Original line number Diff line number Diff line 
// 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);

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