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s390/kernel: expand exception table logic to allow new handling options

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This is a s390 port of commit 548acf1923 ("x86/mm: Expand the
exception table logic to allow new handling options"), which is needed
for implementing BPF_PROBE_MEM on s390.

The new handler field is made 64-bit in order to allow pointing from
dynamically allocated entries to handlers in kernel text. Unlike on x86,
NULL is used instead of ex_handler_default. This is because exception
tables are used by boot/text_dma.S, and it would be a pain to preserve
ex_handler_default.

The new infrastructure is ignored in early_pgm_check_handler, since
there is no pt_regs.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
This commit is contained in:
Ilya Leoshkevich 2020-06-30 20:52:03 +02:00 • committed by Heiko Carstens
parent 88aa8939c9
commit 05a68e892e
6 changed files with 94 additions and 17 deletions
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41
scripts/sorttable.c
View file

@ -255,6 +255,45 @@ static void x86_sort_relative_table(char *extab_image, int image_size)
}
}
static void s390_sort_relative_table(char *extab_image, int image_size)
{
int i;
for (i = 0; i < image_size; i += 16) {
char *loc = extab_image + i;
uint64_t handler;
w(r((uint32_t *)loc) + i, (uint32_t *)loc);
w(r((uint32_t *)(loc + 4)) + (i + 4), (uint32_t *)(loc + 4));
/*
* 0 is a special self-relative handler value, which means that
* handler should be ignored. It is safe, because it means that
* handler field points to itself, which should never happen.
* When creating extable-relative values, keep it as 0, since
* this should never occur either: it would mean that handler
* field points to the first extable entry.
*/
handler = r8((uint64_t *)(loc + 8));
if (handler)
handler += i + 8;
w8(handler, (uint64_t *)(loc + 8));
}
qsort(extab_image, image_size / 16, 16, compare_relative_table);
for (i = 0; i < image_size; i += 16) {
char *loc = extab_image + i;
uint64_t handler;
w(r((uint32_t *)loc) - i, (uint32_t *)loc);
w(r((uint32_t *)(loc + 4)) - (i + 4), (uint32_t *)(loc + 4));
handler = r8((uint64_t *)(loc + 8));
if (handler)
handler -= i + 8;
w8(handler, (uint64_t *)(loc + 8));
}
}
static int do_file(char const *const fname, void *addr)
{
int rc = -1;
@ -297,6 +336,8 @@ static int do_file(char const *const fname, void *addr)
custom_sort = x86_sort_relative_table;
break;
case EM_S390:
custom_sort = s390_sort_relative_table;
break;
case EM_AARCH64:
case EM_PARISC:
case EM_PPC: