s390/exceptions: switch to relative exception table entries
This is the s390 port of 70627654 "x86, extable: Switch to relative
exception table entries".
Reduces the size of our exception tables by 50% on 64 bit builds.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/include/asm/processor.h b/arch/s390/include/asm/processor.h
index 7e81ff1..f3e0aab 100644
--- a/arch/s390/include/asm/processor.h
+++ b/arch/s390/include/asm/processor.h
@@ -11,6 +11,8 @@
#ifndef __ASM_S390_PROCESSOR_H
#define __ASM_S390_PROCESSOR_H
+#ifndef __ASSEMBLY__
+
#include <linux/linkage.h>
#include <linux/irqflags.h>
#include <asm/cpu.h>
@@ -348,23 +350,6 @@
#define ARCH_LOW_ADDRESS_LIMIT 0x7fffffffUL
-/*
- * Helper macro for exception table entries
- */
-#ifndef CONFIG_64BIT
-#define EX_TABLE(_fault,_target) \
- ".section __ex_table,\"a\"\n" \
- " .align 4\n" \
- " .long " #_fault "," #_target "\n" \
- ".previous\n"
-#else
-#define EX_TABLE(_fault,_target) \
- ".section __ex_table,\"a\"\n" \
- " .align 8\n" \
- " .quad " #_fault "," #_target "\n" \
- ".previous\n"
-#endif
-
extern int memcpy_real(void *, void *, size_t);
extern void memcpy_absolute(void *, void *, size_t);
@@ -375,4 +360,25 @@
memcpy_absolute(&(dest), &__tmp, sizeof(__tmp)); \
}
-#endif /* __ASM_S390_PROCESSOR_H */
+/*
+ * Helper macro for exception table entries
+ */
+#define EX_TABLE(_fault, _target) \
+ ".section __ex_table,\"a\"\n" \
+ ".align 4\n" \
+ ".long (" #_fault ") - .\n" \
+ ".long (" #_target ") - .\n" \
+ ".previous\n"
+
+#else /* __ASSEMBLY__ */
+
+#define EX_TABLE(_fault, _target) \
+ .section __ex_table,"a" ; \
+ .align 4 ; \
+ .long (_fault) - . ; \
+ .long (_target) - . ; \
+ .previous
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* __ASM_S390_PROCESSOR_H */
diff --git a/arch/s390/include/asm/uaccess.h b/arch/s390/include/asm/uaccess.h
index a8ab18b..34268df 100644
--- a/arch/s390/include/asm/uaccess.h
+++ b/arch/s390/include/asm/uaccess.h
@@ -76,9 +76,22 @@
struct exception_table_entry
{
- unsigned long insn, fixup;
+ 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
+
struct uaccess_ops {
size_t (*copy_from_user)(size_t, const void __user *, void *);
size_t (*copy_from_user_small)(size_t, const void __user *, void *);
diff --git a/arch/s390/kernel/early.c b/arch/s390/kernel/early.c
index f4bcdc0..e8000d5 100644
--- a/arch/s390/kernel/early.c
+++ b/arch/s390/kernel/early.c
@@ -255,14 +255,14 @@
static void early_pgm_check_handler(void)
{
- unsigned long addr;
const struct exception_table_entry *fixup;
+ unsigned long addr;
addr = S390_lowcore.program_old_psw.addr;
fixup = search_exception_tables(addr & PSW_ADDR_INSN);
if (!fixup)
disabled_wait(0);
- S390_lowcore.program_old_psw.addr = fixup->fixup | PSW_ADDR_AMODE;
+ S390_lowcore.program_old_psw.addr = extable_fixup(fixup)|PSW_ADDR_AMODE;
}
static noinline __init void setup_lowcore_early(void)
diff --git a/arch/s390/kernel/entry64.S b/arch/s390/kernel/entry64.S
index 95e9d93..7549985 100644
--- a/arch/s390/kernel/entry64.S
+++ b/arch/s390/kernel/entry64.S
@@ -10,6 +10,7 @@
#include <linux/init.h>
#include <linux/linkage.h>
+#include <asm/processor.h>
#include <asm/cache.h>
#include <asm/errno.h>
#include <asm/ptrace.h>
@@ -1008,9 +1009,7 @@
.Lhost_id:
.quad 0
- .section __ex_table,"a"
- .quad sie_loop,sie_fault
- .previous
+ EX_TABLE(sie_loop,sie_fault)
#endif
.section .rodata, "a"
diff --git a/arch/s390/kernel/kprobes.c b/arch/s390/kernel/kprobes.c
index 8aa634f..d1c7214 100644
--- a/arch/s390/kernel/kprobes.c
+++ b/arch/s390/kernel/kprobes.c
@@ -547,7 +547,7 @@
*/
entry = search_exception_tables(regs->psw.addr & PSW_ADDR_INSN);
if (entry) {
- regs->psw.addr = entry->fixup | PSW_ADDR_AMODE;
+ regs->psw.addr = extable_fixup(entry) | PSW_ADDR_AMODE;
return 1;
}
diff --git a/arch/s390/kernel/traps.c b/arch/s390/kernel/traps.c
index 29af526..befc761 100644
--- a/arch/s390/kernel/traps.c
+++ b/arch/s390/kernel/traps.c
@@ -322,7 +322,7 @@
const struct exception_table_entry *fixup;
fixup = search_exception_tables(regs->psw.addr & PSW_ADDR_INSN);
if (fixup)
- regs->psw.addr = fixup->fixup | PSW_ADDR_AMODE;
+ regs->psw.addr = extable_fixup(fixup) | PSW_ADDR_AMODE;
else {
enum bug_trap_type btt;
diff --git a/arch/s390/mm/Makefile b/arch/s390/mm/Makefile
index d98fe90..0f5536b 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 \
- page-states.o gup.o
+ page-states.o gup.o extable.o
obj-$(CONFIG_CMM) += cmm.o
obj-$(CONFIG_HUGETLB_PAGE) += hugetlbpage.o
obj-$(CONFIG_DEBUG_SET_MODULE_RONX) += pageattr.o
diff --git a/arch/s390/mm/extable.c b/arch/s390/mm/extable.c
new file mode 100644
index 0000000..4d1ee88
--- /dev/null
+++ b/arch/s390/mm/extable.c
@@ -0,0 +1,81 @@
+#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;
+ 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;
+}
+
+#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 */
diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index 8b2cac1..ac9122c 100644
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -163,7 +163,7 @@
/* Are we prepared to handle this kernel fault? */
fixup = search_exception_tables(regs->psw.addr & PSW_ADDR_INSN);
if (fixup) {
- regs->psw.addr = fixup->fixup | PSW_ADDR_AMODE;
+ regs->psw.addr = extable_fixup(fixup) | PSW_ADDR_AMODE;
return;
}
diff --git a/scripts/sortextable.c b/scripts/sortextable.c
index 6acf834..f19ddc4 100644
--- a/scripts/sortextable.c
+++ b/scripts/sortextable.c
@@ -161,7 +161,7 @@
#define SORTEXTABLE_64
#include "sortextable.h"
-static int compare_x86_table(const void *a, const void *b)
+static int compare_relative_table(const void *a, const void *b)
{
int32_t av = (int32_t)r(a);
int32_t bv = (int32_t)r(b);
@@ -173,7 +173,7 @@
return 0;
}
-static void sort_x86_table(char *extab_image, int image_size)
+static void sort_relative_table(char *extab_image, int image_size)
{
int i;
@@ -188,7 +188,7 @@
i += 4;
}
- qsort(extab_image, image_size / 8, 8, compare_x86_table);
+ qsort(extab_image, image_size / 8, 8, compare_relative_table);
/* Now denormalize. */
i = 0;
@@ -245,9 +245,9 @@
break;
case EM_386:
case EM_X86_64:
- custom_sort = sort_x86_table;
- break;
case EM_S390:
+ custom_sort = sort_relative_table;
+ break;
case EM_MIPS:
break;
} /* end switch */