Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753779AbaDXV3I (ORCPT ); Thu, 24 Apr 2014 17:29:08 -0400 Received: from mail-la0-f45.google.com ([209.85.215.45]:33951 "EHLO mail-la0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753098AbaDXV3F (ORCPT ); Thu, 24 Apr 2014 17:29:05 -0400 From: Rabin Vincent To: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org, Kees Cook , Laura Abbott , Jon Medhurst , Doug Anderson , Rabin Vincent Subject: [PATCHv2 2/2] arm: use fixmap for text patching when text is RO Date: Thu, 24 Apr 2014 23:28:57 +0200 Message-Id: <1398374937-18868-1-git-send-email-rabin@rab.in> X-Mailer: git-send-email 1.9.2 In-Reply-To: <1396646870-29695-2-git-send-email-rabin@rab.in> References: <1396646870-29695-2-git-send-email-rabin@rab.in> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Use fixmaps for text patching when the kernel text is read-only, inspired by x86. This makes jump labels and kprobes work with the currently available CONFIG_DEBUG_SET_MODULE_RONX and the upcoming CONFIG_DEBUG_RODATA options. Signed-off-by: Rabin Vincent --- v2: flush the fixmap if necessary, with flush_kernel_vmap_range() arch/arm/include/asm/fixmap.h | 3 ++ arch/arm/kernel/jump_label.c | 2 +- arch/arm/kernel/patch.c | 71 ++++++++++++++++++++++++++++++++++++++----- arch/arm/kernel/patch.h | 12 +++++++- 4 files changed, 79 insertions(+), 9 deletions(-) diff --git a/arch/arm/include/asm/fixmap.h b/arch/arm/include/asm/fixmap.h index 55ed076..79c1719 100644 --- a/arch/arm/include/asm/fixmap.h +++ b/arch/arm/include/asm/fixmap.h @@ -18,6 +18,9 @@ #define FIXADDR_TOP (FIXADDR_END - PAGE_SIZE) enum fixed_addresses { + FIX_TEXT_POKE0, + FIX_TEXT_POKE1, + FIX_KMAP_BEGIN, FIX_KMAP_END = (FIXADDR_TOP - FIXADDR_START) >> PAGE_SHIFT, __end_of_fixed_addresses diff --git a/arch/arm/kernel/jump_label.c b/arch/arm/kernel/jump_label.c index 4ce4f78..afeeb9e 100644 --- a/arch/arm/kernel/jump_label.c +++ b/arch/arm/kernel/jump_label.c @@ -19,7 +19,7 @@ static void __arch_jump_label_transform(struct jump_entry *entry, insn = arm_gen_nop(); if (is_static) - __patch_text(addr, insn); + __patch_text_early(addr, insn); else patch_text(addr, insn); } diff --git a/arch/arm/kernel/patch.c b/arch/arm/kernel/patch.c index 07314af..3515b8d 100644 --- a/arch/arm/kernel/patch.c +++ b/arch/arm/kernel/patch.c @@ -1,8 +1,11 @@ #include +#include #include +#include #include #include +#include #include #include @@ -13,21 +16,70 @@ struct patch { unsigned int insn; }; -void __kprobes __patch_text(void *addr, unsigned int insn) +static DEFINE_SPINLOCK(patch_lock); + +static void __kprobes *patch_map(void *addr, int fixmap, unsigned long *flags) +{ + unsigned int uintaddr = (uintptr_t) addr; + bool module = !core_kernel_text(uintaddr); + struct page *page; + + if (module && IS_ENABLED(CONFIG_DEBUG_SET_MODULE_RONX)) { + page = vmalloc_to_page(addr); + } else if (!module && IS_ENABLED(CONFIG_ARM_KERNMEM_PERMS)) { + page = virt_to_page(addr); + } else { + return addr; + } + + if (flags) + spin_lock_irqsave(&patch_lock, *flags); + + set_fixmap(fixmap, page_to_phys(page)); + + return (void *) (__fix_to_virt(fixmap) + (uintaddr & ~PAGE_MASK)); +} + +static void __kprobes patch_unmap(int fixmap, unsigned long *flags) +{ + clear_fixmap(fixmap); + + if (flags) + spin_unlock_irqrestore(&patch_lock, *flags); +} + +void __kprobes __patch_text_real(void *addr, unsigned int insn, bool remap) { bool thumb2 = IS_ENABLED(CONFIG_THUMB2_KERNEL); + unsigned int uintaddr = (uintptr_t) addr; + bool twopage = false; + unsigned long flags; + void *waddr = addr; int size; + if (remap) + waddr = patch_map(addr, FIX_TEXT_POKE0, &flags); + if (thumb2 && __opcode_is_thumb16(insn)) { - *(u16 *)addr = __opcode_to_mem_thumb16(insn); + *(u16 *)waddr = __opcode_to_mem_thumb16(insn); size = sizeof(u16); - } else if (thumb2 && ((uintptr_t)addr & 2)) { + } else if (thumb2 && (uintaddr & 2)) { u16 first = __opcode_thumb32_first(insn); u16 second = __opcode_thumb32_second(insn); - u16 *addrh = addr; + u16 *addrh0 = waddr; + u16 *addrh1 = waddr + 2; - addrh[0] = __opcode_to_mem_thumb16(first); - addrh[1] = __opcode_to_mem_thumb16(second); + twopage = (uintaddr & ~PAGE_MASK) == PAGE_SIZE - 2; + if (twopage && remap) + addrh1 = patch_map(addr + 2, FIX_TEXT_POKE1, NULL); + + *addrh0 = __opcode_to_mem_thumb16(first); + *addrh1 = __opcode_to_mem_thumb16(second); + + if (twopage && addrh1 != addr + 2) { + flush_kernel_vmap_range(addrh1, 2); + patch_unmap(FIX_TEXT_POKE1, NULL); + } size = sizeof(u32); } else { @@ -36,10 +88,15 @@ void __kprobes __patch_text(void *addr, unsigned int insn) else insn = __opcode_to_mem_arm(insn); - *(u32 *)addr = insn; + *(u32 *)waddr = insn; size = sizeof(u32); } + if (waddr != addr) { + flush_kernel_vmap_range(waddr, twopage ? size / 2 : size); + patch_unmap(FIX_TEXT_POKE0, &flags); + } + flush_icache_range((uintptr_t)(addr), (uintptr_t)(addr) + size); } diff --git a/arch/arm/kernel/patch.h b/arch/arm/kernel/patch.h index b4731f2..77e054c 100644 --- a/arch/arm/kernel/patch.h +++ b/arch/arm/kernel/patch.h @@ -2,6 +2,16 @@ #define _ARM_KERNEL_PATCH_H void patch_text(void *addr, unsigned int insn); -void __patch_text(void *addr, unsigned int insn); +void __patch_text_real(void *addr, unsigned int insn, bool remap); + +static inline void __patch_text(void *addr, unsigned int insn) +{ + __patch_text_real(addr, insn, true); +} + +static inline void __patch_text_early(void *addr, unsigned int insn) +{ + __patch_text_real(addr, insn, false); +} #endif -- 1.9.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/