From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755801Ab2IKRj6 (ORCPT ); Tue, 11 Sep 2012 13:39:58 -0400 Received: from devils.ext.ti.com ([198.47.26.153]:33206 "EHLO devils.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754732Ab2IKRjw (ORCPT ); Tue, 11 Sep 2012 13:39:52 -0400 From: Cyril Chemparathy To: , CC: , , , , , , Cyril Chemparathy Subject: [PATCH v3 02/17] ARM: add self test for runtime patch mechanism Date: Tue, 11 Sep 2012 13:39:00 -0400 Message-ID: <1347385155-11643-3-git-send-email-cyril@ti.com> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1347385155-11643-1-git-send-email-cyril@ti.com> References: <1347385155-11643-1-git-send-email-cyril@ti.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This patch adds basic sanity tests to ensure that the instruction patching results in valid instruction encodings. This is done by verifying the output of the patch process against a vector of assembler generated instructions at init time. Signed-off-by: Cyril Chemparathy --- arch/arm/Kconfig | 12 +++++++ arch/arm/kernel/runtime-patch.c | 75 +++++++++++++++++++++++++++++++++++++++ 2 files changed, 87 insertions(+) diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 36de4ea..bfcd29d 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -207,6 +207,18 @@ config ARM_PATCH_PHYS_VIRT this feature (eg, building a kernel for a single machine) and you need to shrink the kernel to the minimal size. +config ARM_RUNTIME_PATCH_TEST + bool "Self test runtime patching mechanism" if ARM_RUNTIME_PATCH + default y + help + Select this to enable init time self checking for the runtime kernel + patching mechanism. This enables an ISA specific set of tests that + ensure that the instructions generated by the patch process are + consistent with those generated by the assembler at compile time. + + Only disable this option if you need to shrink the kernel to the + minimal size. + config NEED_MACH_IO_H bool help diff --git a/arch/arm/kernel/runtime-patch.c b/arch/arm/kernel/runtime-patch.c index 28a6367..0be9ef3 100644 --- a/arch/arm/kernel/runtime-patch.c +++ b/arch/arm/kernel/runtime-patch.c @@ -168,6 +168,78 @@ static int apply_patch_imm8(const struct patch_info *p) return 0; } +#ifdef CONFIG_ARM_RUNTIME_PATCH_TEST + +struct patch_test_imm8 { + u16 imm; + u16 shift; + u32 insn; +}; + +static void __init __used __naked __patch_test_code_imm8(void) +{ + __asm__ __volatile__ ( + + /* a single test case */ + " .macro test_one, imm, sft\n" + " .hword \\imm\n" + " .hword \\sft\n" + " add r1, r2, #(\\imm << \\sft)\n" + " .endm\n" + + /* a sequence of tests at 'inc' increments of shift */ + " .macro test_seq, imm, sft, max, inc\n" + " test_one \\imm, \\sft\n" + " .if \\sft < \\max\n" + " test_seq \\imm, (\\sft + \\inc), \\max, \\inc\n" + " .endif\n" + " .endm\n" + + /* an empty record to mark the end */ + " .macro test_end\n" + " .hword 0, 0\n" + " .word 0\n" + " .endm\n" + + /* finally generate the test sequences */ + " test_seq 0x41, 0, 24, 1\n" + " test_seq 0x81, 0, 24, 2\n" + " test_end\n" + : : : "r1", "r2", "cc"); +} + +static void __init test_patch_imm8(void) +{ + u32 test_code_addr = (u32)(&__patch_test_code_imm8); + struct patch_test_imm8 *test = (void *)(test_code_addr & ~1); + u32 ninsn, insn, patched_insn; + int i, err; + + insn = test[0].insn; + for (i = 0; test[i].insn; i++) { + err = do_patch_imm8(insn, test[i].imm << test[i].shift, &ninsn); + __patch_text(&patched_insn, ninsn); + + if (err) { + pr_err("rtpatch imm8: failed at imm %x, shift %d\n", + test[i].imm, test[i].shift); + } else if (patched_insn != test[i].insn) { + pr_err("rtpatch imm8: failed, need %x got %x\n", + test[i].insn, patched_insn); + } else { + pr_debug("rtpatch imm8: imm %x, shift %d, %x -> %x\n", + test[i].imm, test[i].shift, insn, + patched_insn); + } + } +} + +static void __init runtime_patch_test(void) +{ + test_patch_imm8(); +} +#endif + int runtime_patch(const void *table, unsigned size) { const struct patch_info *p = table, *end = (table + size); @@ -189,5 +261,8 @@ void __init runtime_patch_kernel(void) const void *start = &__runtime_patch_table_begin; const void *end = &__runtime_patch_table_end; +#ifdef CONFIG_ARM_RUNTIME_PATCH_TEST + runtime_patch_test(); +#endif BUG_ON(runtime_patch(start, end - start)); } -- 1.7.9.5