From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AB8JxZor1mPzhq+o4QkAyGSetekQ0IlajBCgrnVpXr1Hl5sD6K+jKMwCsXziBjw9e9P6OuKDnPST ARC-Seal: i=1; a=rsa-sha256; t=1525116402; cv=none; d=google.com; s=arc-20160816; b=tS51hCQ8DtpUg7KLvdTFJ+cF7I7Yr5BdFmHG0V0fsQMfIcWEnOohGm1ZyolpbY2KZn 2H0MFK1lB57Y1WLoQE/fTYUB1edtLqiB6jXcUZs5pronrHyQwhBJp5U6Q9/w18FtQgu1 8Ddltt+hiR+scuYQKewnIjUEjbGiljZVy+eZqB4WUMggbbKuRPXVtxi1FgRlk30QQmFd azLZHGIe+OZvJqVyuyC7yBTs1EHAI+aqCGjIyLwytvbOVN/XDS3BJJ2rJ2ZoRjQLB79T 694gU235PUEarN6kZvUTKh2s9TSxVWTxEW86B6EzOJ32l5oTmV+VB/PLbuR5QFaTXIcC BmDg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=mime-version:user-agent:references:in-reply-to:message-id:date :subject:cc:to:from:dmarc-filter:arc-authentication-results; bh=eubIFyvpDQ+fAXaNUMdqVqyknFFvTh/vPXHkJHMBIuw=; b=qm8R1UKA7MuMWHkIOBSuRekECKMekGRnWDgHBUSEbWKaUUO5X2UMLToWwM7vE/m1wK T4O/XAd1BX48kRwm7OISpU5bkuD4VGxUSOumCQ+QL1a4qjU+BmTXu8JVQfa7VpdAwaLw c08e6f5eUJNWoDxqDiKAdZ3KfsZcYXhB/xWQDaGwJwcY4QGIYK1BFm7yvoobL0Zgfl7k zAWnfDgi/WoJhOAISWOlJZdZtU4EnaWOTk/SJYdyJZsmJYsaebz1n04BUoqle6PEvtfz uddJObEB3iWaZVYXErCoWU4nnuDa2/FB8Sigs3XWGEk/gWCJSEUrOUVWHo/4k3lvutWf t0pw== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of srs0=k66p=ht=linuxfoundation.org=gregkh@kernel.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=SRS0=K66P=HT=linuxfoundation.org=gregkh@kernel.org Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of srs0=k66p=ht=linuxfoundation.org=gregkh@kernel.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=SRS0=K66P=HT=linuxfoundation.org=gregkh@kernel.org DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2D3D922DCB Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=fail smtp.mailfrom=gregkh@linuxfoundation.org From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Daniel Kurtz , Aaron Durbin , Rob Herring , Guenter Roeck Subject: [PATCH 4.9 52/61] earlycon: Use a pointer table to fix __earlycon_table stride Date: Mon, 30 Apr 2018 12:24:55 -0700 Message-Id: <20180430183955.764509891@linuxfoundation.org> X-Mailer: git-send-email 2.17.0 In-Reply-To: <20180430183951.312721450@linuxfoundation.org> References: <20180430183951.312721450@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-LABELS: =?utf-8?b?IlxcU2VudCI=?= X-GMAIL-THRID: =?utf-8?q?1599200457375038545?= X-GMAIL-MSGID: =?utf-8?q?1599200457375038545?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Daniel Kurtz commit dd709e72cb934eefd44de8d9969097173fbf45dc upstream. Commit 99492c39f39f ("earlycon: Fix __earlycon_table stride") tried to fix __earlycon_table stride by forcing the earlycon_id struct alignment to 32 and asking the linker to 32-byte align the __earlycon_table symbol. This fix was based on commit 07fca0e57fca92 ("tracing: Properly align linker defined symbols") which tried a similar fix for the tracing subsystem. However, this fix doesn't quite work because there is no guarantee that gcc will place structures packed into an array format. In fact, gcc 4.9 chooses to 64-byte align these structs by inserting additional padding between the entries because it has no clue that they are supposed to be in an array. If we are unlucky, the linker will assign symbol "__earlycon_table" to a 32-byte aligned address which does not correspond to the 64-byte aligned contents of section "__earlycon_table". To address this same problem, the fix to the tracing system was subsequently re-implemented using a more robust table of pointers approach by commits: 3d56e331b653 ("tracing: Replace syscall_meta_data struct array with pointer array") 654986462939 ("tracepoints: Fix section alignment using pointer array") e4a9ea5ee7c8 ("tracing: Replace trace_event struct array with pointer array") Let's use this same "array of pointers to structs" approach for EARLYCON_TABLE. Fixes: 99492c39f39f ("earlycon: Fix __earlycon_table stride") Signed-off-by: Daniel Kurtz Suggested-by: Aaron Durbin Reviewed-by: Rob Herring Tested-by: Guenter Roeck Reviewed-by: Guenter Roeck Cc: stable Signed-off-by: Greg Kroah-Hartman --- drivers/of/fdt.c | 7 +++++-- drivers/tty/serial/earlycon.c | 6 ++++-- include/asm-generic/vmlinux.lds.h | 2 +- include/linux/serial_core.h | 21 ++++++++++++++------- 4 files changed, 24 insertions(+), 12 deletions(-) --- a/drivers/of/fdt.c +++ b/drivers/of/fdt.c @@ -935,7 +935,7 @@ int __init early_init_dt_scan_chosen_std int offset; const char *p, *q, *options = NULL; int l; - const struct earlycon_id *match; + const struct earlycon_id **p_match; const void *fdt = initial_boot_params; offset = fdt_path_offset(fdt, "/chosen"); @@ -962,7 +962,10 @@ int __init early_init_dt_scan_chosen_std return 0; } - for (match = __earlycon_table; match < __earlycon_table_end; match++) { + for (p_match = __earlycon_table; p_match < __earlycon_table_end; + p_match++) { + const struct earlycon_id *match = *p_match; + if (!match->compatible[0]) continue; --- a/drivers/tty/serial/earlycon.c +++ b/drivers/tty/serial/earlycon.c @@ -172,7 +172,7 @@ static int __init register_earlycon(char */ int __init setup_earlycon(char *buf) { - const struct earlycon_id *match; + const struct earlycon_id **p_match; if (!buf || !buf[0]) return -EINVAL; @@ -180,7 +180,9 @@ int __init setup_earlycon(char *buf) if (early_con.flags & CON_ENABLED) return -EALREADY; - for (match = __earlycon_table; match < __earlycon_table_end; match++) { + for (p_match = __earlycon_table; p_match < __earlycon_table_end; + p_match++) { + const struct earlycon_id *match = *p_match; size_t len = strlen(match->name); if (strncmp(buf, match->name, len)) --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -170,7 +170,7 @@ #endif #ifdef CONFIG_SERIAL_EARLYCON -#define EARLYCON_TABLE() STRUCT_ALIGN(); \ +#define EARLYCON_TABLE() . = ALIGN(8); \ VMLINUX_SYMBOL(__earlycon_table) = .; \ *(__earlycon_table) \ VMLINUX_SYMBOL(__earlycon_table_end) = .; --- a/include/linux/serial_core.h +++ b/include/linux/serial_core.h @@ -347,10 +347,10 @@ struct earlycon_id { char name[16]; char compatible[128]; int (*setup)(struct earlycon_device *, const char *options); -} __aligned(32); +}; -extern const struct earlycon_id __earlycon_table[]; -extern const struct earlycon_id __earlycon_table_end[]; +extern const struct earlycon_id *__earlycon_table[]; +extern const struct earlycon_id *__earlycon_table_end[]; #if defined(CONFIG_SERIAL_EARLYCON) && !defined(MODULE) #define EARLYCON_USED_OR_UNUSED __used @@ -358,12 +358,19 @@ extern const struct earlycon_id __earlyc #define EARLYCON_USED_OR_UNUSED __maybe_unused #endif -#define OF_EARLYCON_DECLARE(_name, compat, fn) \ - static const struct earlycon_id __UNIQUE_ID(__earlycon_##_name) \ - EARLYCON_USED_OR_UNUSED __section(__earlycon_table) \ +#define _OF_EARLYCON_DECLARE(_name, compat, fn, unique_id) \ + static const struct earlycon_id unique_id \ + EARLYCON_USED_OR_UNUSED __initconst \ = { .name = __stringify(_name), \ .compatible = compat, \ - .setup = fn } + .setup = fn }; \ + static const struct earlycon_id EARLYCON_USED_OR_UNUSED \ + __section(__earlycon_table) \ + * const __PASTE(__p, unique_id) = &unique_id + +#define OF_EARLYCON_DECLARE(_name, compat, fn) \ + _OF_EARLYCON_DECLARE(_name, compat, fn, \ + __UNIQUE_ID(__earlycon_##_name)) #define EARLYCON_DECLARE(_name, fn) OF_EARLYCON_DECLARE(_name, "", fn)