[PATCH 3/6] s390/extable: use generic search and sort routines

From: Ard Biesheuvel
Date: Sun Jan 03 2016 - 11:06:48 EST


Replace the arch specific versions of search_extable() and sort_extable()
with calls to the generic ones, which now support relative exception
tables as well.

Cc: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Cc: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
---
arch/s390/include/asm/uaccess.h | 8 +-
arch/s390/mm/Makefile | 2 +-
arch/s390/mm/extable.c | 85 --------------------
3 files changed, 2 insertions(+), 93 deletions(-)

diff --git a/arch/s390/include/asm/uaccess.h b/arch/s390/include/asm/uaccess.h
index 9dd4cc47ddc7..e0900ddf91dd 100644
--- a/arch/s390/include/asm/uaccess.h
+++ b/arch/s390/include/asm/uaccess.h
@@ -79,18 +79,12 @@ struct exception_table_entry
int insn, fixup;
};

-static inline unsigned long extable_insn(const struct exception_table_entry *x)
-{
- return (unsigned long)&x->insn + x->insn;
-}
-
static inline unsigned long extable_fixup(const struct exception_table_entry *x)
{
return (unsigned long)&x->fixup + x->fixup;
}

-#define ARCH_HAS_SORT_EXTABLE
-#define ARCH_HAS_SEARCH_EXTABLE
+#define ARCH_HAS_RELATIVE_EXTABLE

/**
* __copy_from_user: - Copy a block of data from user space, with less checking.
diff --git a/arch/s390/mm/Makefile b/arch/s390/mm/Makefile
index 839592ca265c..479550dae80e 100644
--- a/arch/s390/mm/Makefile
+++ b/arch/s390/mm/Makefile
@@ -3,7 +3,7 @@
#

obj-y := init.o fault.o extmem.o mmap.o vmem.o pgtable.o maccess.o
-obj-y += page-states.o gup.o extable.o pageattr.o mem_detect.o
+obj-y += page-states.o gup.o pageattr.o mem_detect.o

obj-$(CONFIG_CMM) += cmm.o
obj-$(CONFIG_HUGETLB_PAGE) += hugetlbpage.o
diff --git a/arch/s390/mm/extable.c b/arch/s390/mm/extable.c
deleted file mode 100644
index 18c8b819b0aa..000000000000
--- a/arch/s390/mm/extable.c
+++ /dev/null
@@ -1,85 +0,0 @@
-#include <linux/module.h>
-#include <linux/sort.h>
-#include <asm/uaccess.h>
-
-/*
- * Search one exception table for an entry corresponding to the
- * given instruction address, and return the address of the entry,
- * or NULL if none is found.
- * We use a binary search, and thus we assume that the table is
- * already sorted.
- */
-const struct exception_table_entry *
-search_extable(const struct exception_table_entry *first,
- const struct exception_table_entry *last,
- unsigned long value)
-{
- const struct exception_table_entry *mid;
- unsigned long addr;
-
- while (first <= last) {
- mid = ((last - first) >> 1) + first;
- addr = extable_insn(mid);
- if (addr < value)
- first = mid + 1;
- else if (addr > value)
- last = mid - 1;
- else
- return mid;
- }
- return NULL;
-}
-
-/*
- * The exception table needs to be sorted so that the binary
- * search that we use to find entries in it works properly.
- * This is used both for the kernel exception table and for
- * the exception tables of modules that get loaded.
- *
- */
-static int cmp_ex(const void *a, const void *b)
-{
- const struct exception_table_entry *x = a, *y = b;
-
- /* This compare is only valid after normalization. */
- return x->insn - y->insn;
-}
-
-void sort_extable(struct exception_table_entry *start,
- struct exception_table_entry *finish)
-{
- struct exception_table_entry *p;
- int i;
-
- /* Normalize entries to being relative to the start of the section */
- for (p = start, i = 0; p < finish; p++, i += 8) {
- p->insn += i;
- p->fixup += i + 4;
- }
- sort(start, finish - start, sizeof(*start), cmp_ex, NULL);
- /* Denormalize all entries */
- for (p = start, i = 0; p < finish; p++, i += 8) {
- p->insn -= i;
- p->fixup -= i + 4;
- }
-}
-
-#ifdef CONFIG_MODULES
-/*
- * If the exception table is sorted, any referring to the module init
- * will be at the beginning or the end.
- */
-void trim_init_extable(struct module *m)
-{
- /* Trim the beginning */
- while (m->num_exentries &&
- within_module_init(extable_insn(&m->extable[0]), m)) {
- m->extable++;
- m->num_exentries--;
- }
- /* Trim the end */
- while (m->num_exentries &&
- within_module_init(extable_insn(&m->extable[m->num_exentries-1]), m))
- m->num_exentries--;
-}
-#endif /* CONFIG_MODULES */
--
1.9.1

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