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[83.153.85.71]) by smtp.gmail.com with ESMTPSA id c15sm12766055wmd.19.2016.01.11.05.19.51 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Mon, 11 Jan 2016 05:19:53 -0800 (PST) From: Ard Biesheuvel To: linux-arm-kernel@lists.infradead.org, kernel-hardening@lists.openwall.com, will.deacon@arm.com, catalin.marinas@arm.com, mark.rutland@arm.com, leif.lindholm@linaro.org, keescook@chromium.org, linux-kernel@vger.kernel.org Cc: stuart.yoder@freescale.com, bhupesh.sharma@freescale.com, arnd@arndb.de, marc.zyngier@arm.com, christoffer.dall@linaro.org, Ard Biesheuvel Subject: [PATCH v3 09/21] extable: add support for relative extables to search and sort routines Date: Mon, 11 Jan 2016 14:19:02 +0100 Message-Id: <1452518355-4606-10-git-send-email-ard.biesheuvel@linaro.org> X-Mailer: git-send-email 2.5.0 In-Reply-To: <1452518355-4606-1-git-send-email-ard.biesheuvel@linaro.org> References: <1452518355-4606-1-git-send-email-ard.biesheuvel@linaro.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This adds support to the generic search_extable() and sort_extable() implementations for dealing with exception table entries whose fields contain relative offsets rather than absolute addresses. Acked-by: Helge Deller Acked-by: Heiko Carstens Acked-by: H. Peter Anvin Acked-by: Tony Luck Acked-by: Will Deacon Signed-off-by: Ard Biesheuvel --- lib/extable.c | 50 ++++++++++++++++---- 1 file changed, 41 insertions(+), 9 deletions(-) -- 2.5.0 diff --git a/lib/extable.c b/lib/extable.c index 4cac81ec225e..0be02ad561e9 100644 --- a/lib/extable.c +++ b/lib/extable.c @@ -14,7 +14,37 @@ #include #include +#ifndef ARCH_HAS_RELATIVE_EXTABLE +#define ex_to_insn(x) ((x)->insn) +#else +static inline unsigned long ex_to_insn(const struct exception_table_entry *x) +{ + return (unsigned long)&x->insn + x->insn; +} +#endif + #ifndef ARCH_HAS_SORT_EXTABLE +#ifndef ARCH_HAS_RELATIVE_EXTABLE +#define swap_ex NULL +#else +static void swap_ex(void *a, void *b, int size) +{ + struct exception_table_entry *x = a, *y = b, tmp; + int delta = b - a; + + tmp = *x; + x->insn = y->insn + delta; + y->insn = tmp.insn - delta; + +#ifdef swap_ex_entry_fixup + swap_ex_entry_fixup(x, y, tmp, delta); +#else + x->fixup = y->fixup + delta; + y->fixup = tmp.fixup - delta; +#endif +} +#endif /* ARCH_HAS_RELATIVE_EXTABLE */ + /* * The exception table needs to be sorted so that the binary * search that we use to find entries in it works properly. @@ -26,9 +56,9 @@ static int cmp_ex(const void *a, const void *b) const struct exception_table_entry *x = a, *y = b; /* avoid overflow */ - if (x->insn > y->insn) + if (ex_to_insn(x) > ex_to_insn(y)) return 1; - if (x->insn < y->insn) + if (ex_to_insn(x) < ex_to_insn(y)) return -1; return 0; } @@ -37,7 +67,7 @@ void sort_extable(struct exception_table_entry *start, struct exception_table_entry *finish) { sort(start, finish - start, sizeof(struct exception_table_entry), - cmp_ex, NULL); + cmp_ex, swap_ex); } #ifdef CONFIG_MODULES @@ -48,13 +78,15 @@ void sort_extable(struct exception_table_entry *start, void trim_init_extable(struct module *m) { /*trim the beginning*/ - while (m->num_exentries && within_module_init(m->extable[0].insn, m)) { + while (m->num_exentries && + within_module_init(ex_to_insn(&m->extable[0]), m)) { m->extable++; m->num_exentries--; } /*trim the end*/ while (m->num_exentries && - within_module_init(m->extable[m->num_exentries-1].insn, m)) + within_module_init(ex_to_insn(&m->extable[m->num_exentries - 1]), + m)) m->num_exentries--; } #endif /* CONFIG_MODULES */ @@ -81,13 +113,13 @@ search_extable(const struct exception_table_entry *first, * careful, the distance between value and insn * can be larger than MAX_LONG: */ - if (mid->insn < value) + if (ex_to_insn(mid) < value) first = mid + 1; - else if (mid->insn > value) + else if (ex_to_insn(mid) > value) last = mid - 1; else return mid; - } - return NULL; + } + return NULL; } #endif