From a94c33dd1f677d16c4f1a162b4b3e9eba1b07c24 Mon Sep 17 00:00:00 2001 From: Thomas Meyer Date: Mon, 10 Jul 2017 15:51:58 -0700 Subject: lib/extable.c: use bsearch() library function in search_extable() [thomas@m3y3r.de: v3: fix arch specific implementations] Link: http://lkml.kernel.org/r/1497890858.12931.7.camel@m3y3r.de Signed-off-by: Thomas Meyer Cc: Rasmus Villemoes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/mips/kernel/module.c | 3 ++- arch/mips/kernel/traps.c | 3 ++- arch/sh/mm/extable_64.c | 34 ++++++++++++++++++---------------- arch/sparc/mm/extable.c | 28 ++++++++++++++-------------- include/linux/extable.h | 5 +++-- kernel/extable.c | 3 ++- kernel/module.c | 2 +- lib/extable.c | 41 +++++++++++++++++++++-------------------- 8 files changed, 63 insertions(+), 56 deletions(-) diff --git a/arch/mips/kernel/module.c b/arch/mips/kernel/module.c index 94627a3a6a0d..50c020c47e54 100644 --- a/arch/mips/kernel/module.c +++ b/arch/mips/kernel/module.c @@ -317,7 +317,8 @@ const struct exception_table_entry *search_module_dbetables(unsigned long addr) spin_lock_irqsave(&dbe_lock, flags); list_for_each_entry(dbe, &dbe_list, dbe_list) { - e = search_extable(dbe->dbe_start, dbe->dbe_end - 1, addr); + e = search_extable(dbe->dbe_start, + dbe->dbe_end - dbe->dbe_start, addr); if (e) break; } diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c index 38dfa27730ff..b68b4d0726d3 100644 --- a/arch/mips/kernel/traps.c +++ b/arch/mips/kernel/traps.c @@ -429,7 +429,8 @@ static const struct exception_table_entry *search_dbe_tables(unsigned long addr) { const struct exception_table_entry *e; - e = search_extable(__start___dbe_table, __stop___dbe_table - 1, addr); + e = search_extable(__start___dbe_table, + __stop___dbe_table - __start___dbe_table, addr); if (!e) e = search_module_dbetables(addr); return e; diff --git a/arch/sh/mm/extable_64.c b/arch/sh/mm/extable_64.c index b90cdfad2c78..7a3b4d33d2e7 100644 --- a/arch/sh/mm/extable_64.c +++ b/arch/sh/mm/extable_64.c @@ -10,6 +10,7 @@ * License. See the file "COPYING" in the main directory of this archive * for more details. */ +#include #include #include #include @@ -40,10 +41,23 @@ static const struct exception_table_entry *check_exception_ranges(unsigned long return NULL; } +static int cmp_ex_search(const void *key, const void *elt) +{ + const struct exception_table_entry *_elt = elt; + unsigned long _key = *(unsigned long *)key; + + /* avoid overflow */ + if (_key > _elt->insn) + return 1; + if (_key < _elt->insn) + return -1; + return 0; +} + /* Simple binary search */ const struct exception_table_entry * -search_extable(const struct exception_table_entry *first, - const struct exception_table_entry *last, +search_extable(const struct exception_table_entry *base, + const size_t num, unsigned long value) { const struct exception_table_entry *mid; @@ -52,20 +66,8 @@ search_extable(const struct exception_table_entry *first, if (mid) return mid; - while (first <= last) { - long diff; - - mid = (last - first) / 2 + first; - diff = mid->insn - value; - if (diff == 0) - return mid; - else if (diff < 0) - first = mid+1; - else - last = mid-1; - } - - return NULL; + return bsearch(&value, base, num, + sizeof(struct exception_table_entry), cmp_ex_search); } int fixup_exception(struct pt_regs *regs) diff --git a/arch/sparc/mm/extable.c b/arch/sparc/mm/extable.c index db214e9931d9..2422511dc8c5 100644 --- a/arch/sparc/mm/extable.c +++ b/arch/sparc/mm/extable.c @@ -13,11 +13,11 @@ void sort_extable(struct exception_table_entry *start, /* Caller knows they are in a range if ret->fixup == 0 */ const struct exception_table_entry * -search_extable(const struct exception_table_entry *start, - const struct exception_table_entry *last, +search_extable(const struct exception_table_entry *base, + const size_t num, unsigned long value) { - const struct exception_table_entry *walk; + int i; /* Single insn entries are encoded as: * word 1: insn address @@ -37,30 +37,30 @@ search_extable(const struct exception_table_entry *start, */ /* 1. Try to find an exact match. */ - for (walk = start; walk <= last; walk++) { - if (walk->fixup == 0) { + for (i = 0; i < num; i++) { + if (base[i].fixup == 0) { /* A range entry, skip both parts. */ - walk++; + i++; continue; } /* A deleted entry; see trim_init_extable */ - if (walk->fixup == -1) + if (base[i].fixup == -1) continue; - if (walk->insn == value) - return walk; + if (base[i].insn == value) + return &base[i]; } /* 2. Try to find a range match. */ - for (walk = start; walk <= (last - 1); walk++) { - if (walk->fixup) + for (i = 0; i < (num - 1); i++) { + if (base[i].fixup) continue; - if (walk[0].insn <= value && walk[1].insn > value) - return walk; + if (base[i].insn <= value && base[i + 1].insn > value) + return &base[i]; - walk++; + i++; } return NULL; diff --git a/include/linux/extable.h b/include/linux/extable.h index 7effea4b257d..28addad0dda7 100644 --- a/include/linux/extable.h +++ b/include/linux/extable.h @@ -2,13 +2,14 @@ #define _LINUX_EXTABLE_H #include /* for NULL */ +#include struct module; struct exception_table_entry; const struct exception_table_entry * -search_extable(const struct exception_table_entry *first, - const struct exception_table_entry *last, +search_extable(const struct exception_table_entry *base, + const size_t num, unsigned long value); void sort_extable(struct exception_table_entry *start, struct exception_table_entry *finish); diff --git a/kernel/extable.c b/kernel/extable.c index 223df4a328a4..38c2412401a1 100644 --- a/kernel/extable.c +++ b/kernel/extable.c @@ -55,7 +55,8 @@ const struct exception_table_entry *search_exception_tables(unsigned long addr) { const struct exception_table_entry *e; - e = search_extable(__start___ex_table, __stop___ex_table-1, addr); + e = search_extable(__start___ex_table, + __stop___ex_table - __start___ex_table, addr); if (!e) e = search_module_extables(addr); return e; diff --git a/kernel/module.c b/kernel/module.c index b3dbdde82e80..b0f92a365140 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -4196,7 +4196,7 @@ const struct exception_table_entry *search_module_extables(unsigned long addr) goto out; e = search_extable(mod->extable, - mod->extable + mod->num_exentries - 1, + mod->num_exentries, addr); out: preempt_enable(); diff --git a/lib/extable.c b/lib/extable.c index 62968daa66a9..f54996fdd0b8 100644 --- a/lib/extable.c +++ b/lib/extable.c @@ -9,6 +9,7 @@ * 2 of the License, or (at your option) any later version. */ +#include #include #include #include @@ -51,7 +52,7 @@ static void swap_ex(void *a, void *b, int size) * 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) +static int cmp_ex_sort(const void *a, const void *b) { const struct exception_table_entry *x = a, *y = b; @@ -67,7 +68,7 @@ void sort_extable(struct exception_table_entry *start, struct exception_table_entry *finish) { sort(start, finish - start, sizeof(struct exception_table_entry), - cmp_ex, swap_ex); + cmp_ex_sort, swap_ex); } #ifdef CONFIG_MODULES @@ -93,6 +94,20 @@ void trim_init_extable(struct module *m) #endif /* !ARCH_HAS_SORT_EXTABLE */ #ifndef ARCH_HAS_SEARCH_EXTABLE + +static int cmp_ex_search(const void *key, const void *elt) +{ + const struct exception_table_entry *_elt = elt; + unsigned long _key = *(unsigned long *)key; + + /* avoid overflow */ + if (_key > ex_to_insn(_elt)) + return 1; + if (_key < ex_to_insn(_elt)) + return -1; + return 0; +} + /* * Search one exception table for an entry corresponding to the * given instruction address, and return the address of the entry, @@ -101,25 +116,11 @@ void trim_init_extable(struct module *m) * already sorted. */ const struct exception_table_entry * -search_extable(const struct exception_table_entry *first, - const struct exception_table_entry *last, +search_extable(const struct exception_table_entry *base, + const size_t num, unsigned long value) { - while (first <= last) { - const struct exception_table_entry *mid; - - mid = ((last - first) >> 1) + first; - /* - * careful, the distance between value and insn - * can be larger than MAX_LONG: - */ - if (ex_to_insn(mid) < value) - first = mid + 1; - else if (ex_to_insn(mid) > value) - last = mid - 1; - else - return mid; - } - return NULL; + return bsearch(&value, base, num, + sizeof(struct exception_table_entry), cmp_ex_search); } #endif -- cgit v1.2.3-59-g8ed1b