regset: Add support for dynamically sized regsets
Currently the regset API doesn't allow for the possibility that
regsets (or at least, the amount of meaningful data in a regset)
may change in size.
In particular, this results in useless padding being added to
coredumps if a regset's current size is smaller than its
theoretical maximum size.
This patch adds a get_size() function to struct user_regset.
Individual regset implementations can implement this function to
return the current size of the regset data. A regset_size()
function is added to provide callers with an abstract interface for
determining the size of a regset without needing to know whether
the regset is dynamically sized or not.
The only affected user of this interface is the ELF coredump code:
This patch ports ELF coredump to dump regsets with their actual
size in the coredump. This has no effect except for new regsets
that are dynamically sized and provide a get_size() implementation.
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Dmitry Safonov <dsafonov@virtuozzo.com>
Cc: H. J. Lu <hjl.tools@gmail.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 73b01e4..c697882 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1699,7 +1699,7 @@ static int fill_thread_core_info(struct elf_thread_core_info *t,
long signr, size_t *total)
{
unsigned int i;
- unsigned int regset_size = view->regsets[0].n * view->regsets[0].size;
+ unsigned int regset0_size = regset_size(t->task, &view->regsets[0]);
/*
* NT_PRSTATUS is the one special case, because the regset data
@@ -1708,11 +1708,11 @@ 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, regset_size,
+ (void) view->regsets[0].get(t->task, &view->regsets[0], 0, regset0_size,
&t->prstatus.pr_reg, NULL);
fill_note(&t->notes[0], "CORE", NT_PRSTATUS,
- PRSTATUS_SIZE(t->prstatus, regset_size), &t->prstatus);
+ PRSTATUS_SIZE(t->prstatus, regset0_size), &t->prstatus);
*total += notesize(&t->notes[0]);
do_thread_regset_writeback(t->task, &view->regsets[0]);
@@ -1728,7 +1728,7 @@ static int fill_thread_core_info(struct elf_thread_core_info *t,
if (regset->core_note_type && regset->get &&
(!regset->active || regset->active(t->task, regset))) {
int ret;
- size_t size = regset->n * regset->size;
+ size_t size = regset_size(t->task, regset);
void *data = kmalloc(size, GFP_KERNEL);
if (unlikely(!data))
return 0;
@@ -1743,7 +1743,7 @@ static int fill_thread_core_info(struct elf_thread_core_info *t,
size, data);
else {
SET_PR_FPVALID(&t->prstatus,
- 1, regset_size);
+ 1, regset0_size);
fill_note(&t->notes[i], "CORE",
NT_PRFPREG, size, data);
}
