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s390/exceptions: switch to relative exception table entries

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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>
This commit is contained in:
Heiko Carstens 2012-09-05 13:26:11 +02:00 committed by Martin Schwidefsky
parent 24996edce5
commit eb608fb366
10 changed files with 132 additions and 33 deletions
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42
arch/s390/include/asm/processor.h
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@ -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 @@ extern void (*s390_base_ext_handler_fn)(void);
#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 @@ extern void memcpy_absolute(void *, void *, size_t);
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 */

15
arch/s390/include/asm/uaccess.h
View File

@ -76,9 +76,22 @@ static inline int __range_ok(unsigned long addr, unsigned long size)
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 *);

4
arch/s390/kernel/early.c
View File

@ -255,14 +255,14 @@ static __init void setup_topology(void)
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)

5
arch/s390/kernel/entry64.S
View File

@ -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 @@ sie_fault:
.Lhost_id:
.quad 0
.section __ex_table,"a"
.quad sie_loop,sie_fault
.previous
EX_TABLE(sie_loop,sie_fault)
#endif
.section .rodata, "a"

2
arch/s390/kernel/kprobes.c
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@ -547,7 +547,7 @@ static int __kprobes kprobe_trap_handler(struct pt_regs *regs, int trapnr)
*/
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;
}

2
arch/s390/kernel/traps.c
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@ -322,7 +322,7 @@ static void __kprobes do_trap(struct pt_regs *regs,
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;

2
arch/s390/mm/Makefile
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@ -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

81
arch/s390/mm/extable.c Normal file
View File

@ -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 */

2
arch/s390/mm/fault.c
View File

@ -163,7 +163,7 @@ static noinline void do_no_context(struct pt_regs *regs)
/* 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;
}

10
scripts/sortextable.c
View File

@ -161,7 +161,7 @@ typedef void (*table_sort_t)(char *, int);
#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 @@ static int compare_x86_table(const void *a, const void *b)
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 @@ static void sort_x86_table(char *extab_image, int image_size)
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 @@ do_file(char const *const fname)
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 */