From patchwork Wed Oct 11 07:26:50 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jinjie Ruan X-Patchwork-Id: 13416767 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 480A4CD98F7 for ; Wed, 11 Oct 2023 07:28:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-ID:Date:Subject:CC:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=ij/PYOjJMEmFz0z9CoPPG3cc22b+tEDTnKUCGsqpY3s=; b=noXM1Q8HncW44R JhBAVoT58NRfQKIh/1forOevWEqDSFyh2D8/D4sIS6eSUioBuRycRnU1yQl58Mw9HYLnlhb2XioHo 0Rykblpd271YkvHiU5JSmKRte/asmd0oXcz51azxk2FwUDBnCtgLi/TtrLEyNYXrxo1e8t6NqQV6W svpMjUMcXQOCEFLick9xFJACuf8YwlE3GJkQn8SeYAHUWEfNYfKdzIS/4fRgBs8SMmG0lWGzD1tK7 bNxmIkiF74AOl0abyk0V1CIxeIgXL+hlHv3Wp/ZAgCM0xVI3WHPxQJzB28pHQAhBwhXztOGHBlkwz qxfT9/t6qJpEWWdLPjBQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qqTdj-00F5Mb-0U; Wed, 11 Oct 2023 07:28:19 +0000 Received: from szxga02-in.huawei.com ([45.249.212.188]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1qqTdV-00F5D9-3B for linux-arm-kernel@lists.infradead.org; Wed, 11 Oct 2023 07:28:10 +0000 Received: from kwepemi500008.china.huawei.com (unknown [172.30.72.55]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4S545D6XQNzLq5B; Wed, 11 Oct 2023 15:24:00 +0800 (CST) Received: from huawei.com (10.67.174.55) by kwepemi500008.china.huawei.com (7.221.188.139) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.31; Wed, 11 Oct 2023 15:27:56 +0800 From: Jinjie Ruan To: , , , , , , , , , , , , , , , , , , CC: Subject: [PATCH v5.10 04/15] arm64: rework FPAC exception handling Date: Wed, 11 Oct 2023 07:26:50 +0000 Message-ID: <20231011072701.876772-5-ruanjinjie@huawei.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20231011072701.876772-1-ruanjinjie@huawei.com> References: <20231011072701.876772-1-ruanjinjie@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.67.174.55] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To kwepemi500008.china.huawei.com (7.221.188.139) X-CFilter-Loop: Reflected X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20231011_002806_448557_8E0878D3 X-CRM114-Status: GOOD ( 14.69 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org From: Mark Rutland If an FPAC exception is taken from EL1, the entry code will call do_ptrauth_fault(), where due to: BUG_ON(!user_mode(regs)) ... the kernel will report a problem within do_ptrauth_fault() rather than reporting the original context the FPAC exception was taken from. The pt_regs and ESR value reported will be from within do_ptrauth_fault() and the code dump will be for the BRK in BUG_ON(), which isn't sufficient to debug the cause of the original exception. This patch makes the reporting better by having separate EL0 and EL1 FPAC exception handlers, with the latter calling die() directly to report the original context the FPAC exception was taken from. Note that we only need to prevent kprobes of the EL1 FPAC handler, since the EL0 FPAC handler cannot be called recursively. For consistency with do_el0_svc*(), I've named the split functions do_el{0,1}_fpac() rather than do_el{0,1}_ptrauth_fault(). I've also clarified the comment to not imply there are casues other than FPAC exceptions. Prior to this patch FPAC exceptions are reported as: | kernel BUG at arch/arm64/kernel/traps.c:517! | Internal error: Oops - BUG: 00000000f2000800 [#1] PREEMPT SMP | Modules linked in: | CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.19.0-rc3-00130-g9c8a180a1cdf-dirty #12 | Hardware name: FVP Base RevC (DT) | pstate: 00400009 (nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) | pc : do_ptrauth_fault+0x3c/0x40 | lr : el1_fpac+0x34/0x54 | sp : ffff80000a3bbc80 | x29: ffff80000a3bbc80 x28: ffff0008001d8000 x27: 0000000000000000 | x26: 0000000000000000 x25: 0000000000000000 x24: 0000000000000000 | x23: 0000000020400009 x22: ffff800008f70fa4 x21: ffff80000a3bbe00 | x20: 0000000072000000 x19: ffff80000a3bbcb0 x18: fffffbfffda37000 | x17: 3120676e696d7573 x16: 7361202c6e6f6974 x15: 0000000081a90000 | x14: 0040000000000041 x13: 0040000000000001 x12: ffff000001a90000 | x11: fffffbfffda37480 x10: 0068000000000703 x9 : 0001000080000000 | x8 : 0000000000090000 x7 : 0068000000000f03 x6 : 0060000000000783 | x5 : ffff80000a3bbcb0 x4 : ffff0008001d8000 x3 : 0000000072000000 | x2 : 0000000000000000 x1 : 0000000020400009 x0 : ffff80000a3bbcb0 | Call trace: | do_ptrauth_fault+0x3c/0x40 | el1h_64_sync_handler+0xc4/0xd0 | el1h_64_sync+0x64/0x68 | test_pac+0x8/0x10 | smp_init+0x7c/0x8c | kernel_init_freeable+0x128/0x28c | kernel_init+0x28/0x13c | ret_from_fork+0x10/0x20 | Code: 97fffe5e a8c17bfd d50323bf d65f03c0 (d4210000) With this patch applied FPAC exceptions are reported as: | Internal error: Oops - FPAC: 0000000072000000 [#1] PREEMPT SMP | Modules linked in: | CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.19.0-rc3-00132-g78846e1c4757-dirty #11 | Hardware name: FVP Base RevC (DT) | pstate: 20400009 (nzCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) | pc : test_pac+0x8/0x10 | lr : 0x0 | sp : ffff80000a3bbe00 | x29: ffff80000a3bbe00 x28: 0000000000000000 x27: 0000000000000000 | x26: 0000000000000000 x25: 0000000000000000 x24: 0000000000000000 | x23: ffff80000a2c8000 x22: 0000000000000000 x21: 0000000000000000 | x20: ffff8000099fa5b0 x19: ffff80000a007000 x18: fffffbfffda37000 | x17: 3120676e696d7573 x16: 7361202c6e6f6974 x15: 0000000081a90000 | x14: 0040000000000041 x13: 0040000000000001 x12: ffff000001a90000 | x11: fffffbfffda37480 x10: 0068000000000703 x9 : 0001000080000000 | x8 : 0000000000090000 x7 : 0068000000000f03 x6 : 0060000000000783 | x5 : ffff80000a2c6000 x4 : ffff0008001d8000 x3 : ffff800009f88378 | x2 : 0000000000000000 x1 : 0000000080210000 x0 : ffff000001a90000 | Call trace: | test_pac+0x8/0x10 | smp_init+0x7c/0x8c | kernel_init_freeable+0x128/0x28c | kernel_init+0x28/0x13c | ret_from_fork+0x10/0x20 | Code: d50323bf d65f03c0 d503233f aa1f03fe (d50323bf) Signed-off-by: Mark Rutland Reviewed-by: Mark Brown Reviewed-by: Anshuman Khandual Cc: Alexandru Elisei Cc: Amit Daniel Kachhap Cc: James Morse Cc: Will Deacon Link: https://lore.kernel.org/r/20220913101732.3925290-5-mark.rutland@arm.com Signed-off-by: Catalin Marinas --- arch/arm64/include/asm/exception.h | 3 ++- arch/arm64/kernel/entry-common.c | 4 ++-- arch/arm64/kernel/traps.c | 16 ++++++++++------ 3 files changed, 14 insertions(+), 9 deletions(-) diff --git a/arch/arm64/include/asm/exception.h b/arch/arm64/include/asm/exception.h index 18f7a095b91e..6c869d1f51cc 100644 --- a/arch/arm64/include/asm/exception.h +++ b/arch/arm64/include/asm/exception.h @@ -47,5 +47,6 @@ void bad_el0_sync(struct pt_regs *regs, int reason, unsigned int esr); void do_cp15instr(unsigned int esr, struct pt_regs *regs); void do_el0_svc(struct pt_regs *regs); void do_el0_svc_compat(struct pt_regs *regs); -void do_ptrauth_fault(struct pt_regs *regs, unsigned int esr); +void do_el0_fpac(struct pt_regs *regs, unsigned long esr); +void do_el1_fpac(struct pt_regs *regs, unsigned long esr); #endif /* __ASM_EXCEPTION_H */ diff --git a/arch/arm64/kernel/entry-common.c b/arch/arm64/kernel/entry-common.c index c1d6720ae397..b17f848a09c5 100644 --- a/arch/arm64/kernel/entry-common.c +++ b/arch/arm64/kernel/entry-common.c @@ -187,7 +187,7 @@ static void noinstr el1_fpac(struct pt_regs *regs, unsigned long esr) { enter_from_kernel_mode(regs); local_daif_inherit(regs); - do_ptrauth_fault(regs, esr); + do_el1_fpac(regs, esr); local_daif_mask(); exit_to_kernel_mode(regs); } @@ -357,7 +357,7 @@ static void noinstr el0_fpac(struct pt_regs *regs, unsigned long esr) { enter_from_user_mode(); local_daif_restore(DAIF_PROCCTX); - do_ptrauth_fault(regs, esr); + do_el0_fpac(regs, esr); } asmlinkage void noinstr el0_sync_handler(struct pt_regs *regs) diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c index 2060ba0ee6b4..5d29ba0d85c1 100644 --- a/arch/arm64/kernel/traps.c +++ b/arch/arm64/kernel/traps.c @@ -418,16 +418,20 @@ void do_bti(struct pt_regs *regs) } NOKPROBE_SYMBOL(do_bti); -void do_ptrauth_fault(struct pt_regs *regs, unsigned int esr) +void do_el0_fpac(struct pt_regs *regs, unsigned long esr) +{ + force_signal_inject(SIGILL, ILL_ILLOPN, regs->pc, esr); +} + +void do_el1_fpac(struct pt_regs *regs, unsigned long esr) { /* - * Unexpected FPAC exception or pointer authentication failure in - * the kernel: kill the task before it does any more harm. + * Unexpected FPAC exception in the kernel: kill the task before it + * does any more harm. */ - BUG_ON(!user_mode(regs)); - force_signal_inject(SIGILL, ILL_ILLOPN, regs->pc, esr); + die("Oops - FPAC", regs, esr); } -NOKPROBE_SYMBOL(do_ptrauth_fault); +NOKPROBE_SYMBOL(do_el1_fpac); #define __user_cache_maint(insn, address, res) \ if (address >= user_addr_max()) { \