Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755211Ab2HLCgA (ORCPT ); Sat, 11 Aug 2012 22:36:00 -0400 Received: from mail-qa0-f53.google.com ([209.85.216.53]:62503 "EHLO mail-qa0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754471Ab2HLCf7 (ORCPT ); Sat, 11 Aug 2012 22:35:59 -0400 Date: Sat, 11 Aug 2012 22:35:56 -0400 (EDT) From: Nicolas Pitre To: Cyril Chemparathy cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, arnd@arndb.de, catalin.marinas@arm.com, grant.likely@secretlab.ca, linux@arm.linux.org.uk, will.deacon@arm.com Subject: Re: [PATCH v2 02/22] ARM: add self test for runtime patch mechanism In-Reply-To: <1344648306-15619-3-git-send-email-cyril@ti.com> Message-ID: References: <1344648306-15619-1-git-send-email-cyril@ti.com> <1344648306-15619-3-git-send-email-cyril@ti.com> User-Agent: Alpine 2.02 (LFD 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3661 Lines: 112 On Fri, 10 Aug 2012, Cyril Chemparathy wrote: > 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 | 41 +++++++++++++++++++++++++++++++++++++++ > 2 files changed, 53 insertions(+) > > diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig > index d0a04ad..7e552dc 100644 > --- a/arch/arm/Kconfig > +++ b/arch/arm/Kconfig > @@ -211,6 +211,18 @@ 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 fd37a2b..c471d8c 100644 > --- a/arch/arm/kernel/runtime-patch.c > +++ b/arch/arm/kernel/runtime-patch.c > @@ -163,6 +163,44 @@ static int apply_patch_imm8(const struct patch_info *p) > return 0; > } > > +#ifdef CONFIG_ARM_RUNTIME_PATCH_TEST > +static void __init __used __naked __patch_test_code_imm8(void) > +{ > + __asm__ __volatile__ ( > + " .irp shift1, 0, 6, 12, 18\n" > + " .irp shift2, 0, 1, 2, 3, 4, 5\n" > + " add r1, r2, #(0x41 << (\\shift1 + \\shift2))\n" > + " .endr\n" > + " .endr\n" Maybe adding a "add r1, r2 #0x81 << 24" here might be a good thing since this is the most used case but missing from the above. > + " .word 0\n" > + : : : > + ); > +} > + > +static void __init test_patch_imm8(void) > +{ > + u32 test_code_addr = (u32)(&__patch_test_code_imm8); > + u32 *test_code = (u32 *)(test_code_addr & ~0x3); Why this masking? With Thumb2 you may find functions starting at halfword aligned addresses. Only the LSB (indicating thumb mode) should be masked out. > + int i, ret; > + u32 ninsn, insn; > + > + insn = test_code[0]; > + for (i = 0; test_code[i]; i++) { > + ret = do_patch_imm8(insn, 0x41 << i, &ninsn); > + if (ret < 0) > + pr_err("runtime patch (imm8): failed at shift %d\n", i); > + else if (ninsn != test_code[i]) > + pr_err("runtime patch (imm8): failed, need %x got %x\n", > + test_code[i], ninsn); > + } > +} > + > +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); > @@ -185,5 +223,8 @@ 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 > -- 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/