From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr1-f71.google.com (mail-wr1-f71.google.com [209.85.221.71]) by kanga.kvack.org (Postfix) with ESMTP id 1854A8E0001 for ; Mon, 21 Jan 2019 08:53:13 -0500 (EST) Received: by mail-wr1-f71.google.com with SMTP id h11so11058514wrs.2 for ; Mon, 21 Jan 2019 05:53:13 -0800 (PST) Received: from mail.skyhub.de (mail.skyhub.de. [5.9.137.197]) by mx.google.com with ESMTPS id r68si33229027wme.104.2019.01.21.05.53.11 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 21 Jan 2019 05:53:11 -0800 (PST) Date: Mon, 21 Jan 2019 14:53:04 +0100 From: Borislav Petkov Subject: Re: [PATCH v7 18/25] ACPI / APEI: Split ghes_read_estatus() to allow a peek at the CPER length Message-ID: <20190121135304.GI29166@zn.tnic> References: <20181203180613.228133-1-james.morse@arm.com> <20181203180613.228133-19-james.morse@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20181203180613.228133-19-james.morse@arm.com> Sender: owner-linux-mm@kvack.org List-ID: To: James Morse Cc: linux-acpi@vger.kernel.org, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, Marc Zyngier , Christoffer Dall , Will Deacon , Catalin Marinas , Naoya Horiguchi , Rafael Wysocki , Len Brown , Tony Luck , Dongjiu Geng , Xie XiuQi , Fan Wu On Mon, Dec 03, 2018 at 06:06:06PM +0000, James Morse wrote: > ghes_read_estatus() reads the record address, then the record's > header, then performs some sanity checks before reading the > records into the provided estatus buffer. > > To provide this estatus buffer the caller must know the size of the > records in advance, or always provide a worst-case sized buffer as > happens today for the non-NMI notifications. > > Add a function to peek at the record's header to find the size. This > will let the NMI path allocate the right amount of memory before reading > the records, instead of using the worst-case size, and having to copy > the records. > > Split ghes_read_estatus() to create __ghes_peek_estatus() which > returns the address and size of the CPER records. > > Signed-off-by: James Morse > > Changes since v6: > * Additional buf_addr = 0 error handling > * Moved checking out of peek-estatus > * Reworded an error message so we can tell them apart > --- > drivers/acpi/apei/ghes.c | 59 ++++++++++++++++++++++++++++++++-------- > 1 file changed, 47 insertions(+), 12 deletions(-) > > diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c > index b70f5fd962cc..07a12aac4c1a 100644 > --- a/drivers/acpi/apei/ghes.c > +++ b/drivers/acpi/apei/ghes.c > @@ -277,12 +277,12 @@ static void ghes_copy_tofrom_phys(void *buffer, u64 paddr, u32 len, > } > } > > -static int ghes_read_estatus(struct ghes *ghes, > - struct acpi_hest_generic_status *estatus, > - u64 *buf_paddr, int fixmap_idx) > +/* Read the CPER block and returning its address, and header in estatus. */ s/and /,/ > +static int __ghes_peek_estatus(struct ghes *ghes, int fixmap_idx, > + struct acpi_hest_generic_status *estatus, Also, we probably should stick to some order of arguments of those functions for easier code staring, i.e. function_name(ghes, estatus, buf_paddr, fixmap_idx) or so. > + u64 *buf_paddr) > { > struct acpi_hest_generic *g = ghes->generic; > - u32 len; > int rc; > > rc = apei_read(buf_paddr, &g->error_status_address); > @@ -303,29 +303,64 @@ static int ghes_read_estatus(struct ghes *ghes, > return -ENOENT; > } > > - rc = -EIO; > - len = cper_estatus_len(estatus); > + return 0; > +} > + > +/* Check the top-level record header has an appropriate size. */ > +int __ghes_check_estatus(struct ghes *ghes, > + struct acpi_hest_generic_status *estatus) > +{ > + u32 len = cper_estatus_len(estatus); > + int rc = -EIO; > + > if (len < sizeof(*estatus)) > goto err_read_block; > if (len > ghes->generic->error_block_length) > goto err_read_block; > if (cper_estatus_check_header(estatus)) > goto err_read_block; Please make this chunk more user-friendly, maybe in a separate patch ontop: /* Check the top-level record header has an appropriate size. */ int __ghes_check_estatus(struct ghes *ghes, struct acpi_hest_generic_status *estatus) { u32 len = cper_estatus_len(estatus); if (len < sizeof(*estatus)) { pr_warn_ratelimited(FW_WARN GHES_PFX "Truncated error status block!\n"); return -EIO; } if (len > ghes->generic->error_block_length) { pr_warn_ratelimited(FW_WARN GHES_PFX "Invalid error status block length!\n"); return -EIO; } if (cper_estatus_check_header(estatus)) { pr_warn_ratelimited(FW_WARN GHES_PFX "Invalid CPER header!\n"); return -EIO; } return 0; } Thx. -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply.