From patchwork Wed Apr 29 17:08:04 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Thompson X-Patchwork-Id: 185847 Delivered-To: patches@linaro.org Received: by 2002:a50:3a95:0:0:0:0:0 with SMTP id v21csp221163ecc; Wed, 29 Apr 2020 10:08:14 -0700 (PDT) X-Received: by 2002:adf:bb84:: with SMTP id q4mr38504417wrg.141.1588180094337; Wed, 29 Apr 2020 10:08:14 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1588180094; cv=none; d=google.com; s=arc-20160816; b=y+TugD3qS1wLv3WX4FDgREVjYmKJHOptwE8viZBwEZMRwYD4MAPRjVXI9KhidBHXNW IPyHhh8Ul/cyjUpuyQDZmMn5fjXyktjN9w4Fd7/Td0N4vF517C9AmI/oIVC+CKbBfK7D DAImYZGHVIcPp1W9CvP1vZTVi3glvxOx7XiZdjQCac0bWbuELVWw2gMql7KW10UZ6NNZ 5xqEydJeRg+5QMJJTLFmFlcm+lJAm5Kksh/lhReBxOh44N0w5hVcOBhJYv9FyHrh/Ine ozq7WiKKtb854CxDDlkdxAj7y2bd/Dw8jdeXX7QOItmenURsssRlSfl3wN66YQO/6JUO u6/g== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:dkim-signature; bh=OmhWnXth/1A2zdJKsZMj2+vlFmsDfxZsIDA5SZ6zP3o=; b=DyFYaBlmSOfHN/p4cxx1MiAroMSd7J56FJqv5Pjw2W5q0UwEJb9MekqX24OgBAwP3+ 4Kd7YGGhjYQbOm647ZOpZT8E9QvwIPg9P5YTCocmTvPNnKQjbY7SReVSRXD3IXQ8egmI 8Gdxf4RDNlNlfDsC/jhjQSuNKV2ifGXWOEBu6U/uYNiGpg15dqdrfTpiue931tXffcV8 9oprGt/ac5ORyHR3qqhwQ4m1U1PqJjcEAmIrs/k0HVsMxAzZavPYLxXX+vgupKAhDExi 4voXpgcHvQMwnZ+9c50KPuMl7zzyBHzAe4Mx4OQH90zxIFWXkj/Lyb+Y7s3FHrKbIGrs JaZg== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@linaro.org header.s=google header.b=mzGwcRnu; spf=pass (google.com: domain of daniel.thompson@linaro.org designates 209.85.220.65 as permitted sender) smtp.mailfrom=daniel.thompson@linaro.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linaro.org Return-Path: Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id j2sor1734074wmi.14.2020.04.29.10.08.14 for (Google Transport Security); Wed, 29 Apr 2020 10:08:14 -0700 (PDT) Received-SPF: pass (google.com: domain of daniel.thompson@linaro.org designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@linaro.org header.s=google header.b=mzGwcRnu; spf=pass (google.com: domain of daniel.thompson@linaro.org designates 209.85.220.65 as permitted sender) smtp.mailfrom=daniel.thompson@linaro.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linaro.org DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=OmhWnXth/1A2zdJKsZMj2+vlFmsDfxZsIDA5SZ6zP3o=; b=mzGwcRnuuGEc7QpRyskmYXkErO6T7vAvIGVnIg2n7qW04qEnZvx5oUzAJ5Gxh4vBjs NorLXIbNm5dyb1Tfp8dSoFvfTHmmsLKQPPnx7WmFOpJ2SykBQwQcLZCWN3p9R1HZY4bz 8g3guOwAnkNKtPtK3s6xABdVtRK1RU4i2n5oin5JlOZ5bm4gsUJx/kJmtmgWmbbLCFos xc+R1s1ojy9dIdQOU7wv/znqlefvErzD9jXK/7HCZa2uXGrHKUTktAt3li0+cJOqDFy4 vGTLaZ9beopEtHUxD7TS3jhipT5yYSD1nJo5COJn1l5HUTI9Pa8XJvwJFO3A+mVJ5JYT ncbg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=OmhWnXth/1A2zdJKsZMj2+vlFmsDfxZsIDA5SZ6zP3o=; b=LDohwDZpWvpiydpp0AVLOjoLENwKgMJUQW3eL4D+MTXBITehUt2BX9rGDL2cHK4ZaD 1hPADO/egj2ddhJ2uEevmlPH4dvyyxfj//syc/Dng6HskMVDGYW+ni17w/55kc1nI8YD MCwHp6xxrfWzds3+WQXfRjd94oQmYbTnzZxQo+l8hKtj7FaN7h7ZSOc9YCDFbGUmp3Z4 8YIaItU6QQwFmP3trZQrjIzypoMhk0M8jvu049rK64/isAkh3pwX/MCW1OqR1nAKqtTh IdKtre9j3rNWoMA1pOXWyavpmnVKT1y8jCr9OhRTyKaruXJB/suUpIsmXlZLHNh30vfY dBgg== X-Gm-Message-State: AGi0PubHC+CM94S4Qk4jYUese0ImG/GrBqMmL7Sm2Jiy2VfoMaH4koMq hZshpN6KmLT3tZG22oJF612MGeAF X-Google-Smtp-Source: APiQypJ6SJj9JFl0Ap0o8f53q6YJ5wKK2xElS/MI2R0BRSXQfNfPFjCqOYRypDRwwlXhYHQgp2OREw== X-Received: by 2002:a05:600c:2c47:: with SMTP id r7mr4272520wmg.50.1588180093830; Wed, 29 Apr 2020 10:08:13 -0700 (PDT) Return-Path: Received: from wychelm.lan (cpc141214-aztw34-2-0-cust773.18-1.cable.virginm.net. [86.9.19.6]) by smtp.gmail.com with ESMTPSA id x18sm8502940wmi.29.2020.04.29.10.08.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 29 Apr 2020 10:08:13 -0700 (PDT) From: Daniel Thompson To: Douglas Anderson Cc: Daniel Thompson , Sumit Garg , linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, patches@linaro.org Subject: [PATCH] serial: kgdboc: Allow earlycon initialization to be deferred Date: Wed, 29 Apr 2020 18:08:04 +0100 Message-Id: <20200429170804.880720-1-daniel.thompson@linaro.org> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 As described in the big comment in the patch, earlycon initialization can be deferred if, a) earlycon was supplied without arguments and, b) the ACPI SPCR table hasn't yet been parsed. Unfortunately, if deferred, then the earlycon is not ready during early parameter parsing so kgdboc cannot use it. This patch mitigates the problem by giving kgdboc_earlycon a second chance during dbg_late_init(). Adding a special purpose interface slightly increase the intimacy between kgdboc and debug-core but this seems better than adding kgdb specific hooks into the arch code (and much, much better than faking non-intimacy with function pointers). Signed-off-by: Daniel Thompson --- Notes: Hi Doug, This patch extends your patch set to make it easier to deploy on ACPI systems[1]: earlycon kgdboc_earlycon kgdboc=ttyAMA0 I have mixed feeling about it because it adds calls from debug-core into kgdboc and I don't think there are other examples of this. However earlycon auto-configuration is so awesome I'd like to be able to keep using it and this is the best I have come up with so far ;-). Daniel. [1] And also on DT based arm64 systems that have ACPI support enabled at compile time because such systems don't decide whether to adopt DT or ACPI until after early parameter parsing. drivers/tty/serial/kgdboc.c | 26 +++++++++++++++++++++++++- include/linux/kgdb.h | 2 ++ kernel/debug/debug_core.c | 4 ++++ 3 files changed, 31 insertions(+), 1 deletion(-) base-commit: 6a8b55ed4056ea5559ebe4f6a4b247f627870d4c prerequisite-patch-id: cbaa70eb783f1f34aec7f5839d1fecbc7616a9f6 prerequisite-patch-id: d7543cdd19fb194ded3361d52818970083efdb06 prerequisite-patch-id: 2238d976451dac9e3ee1bf02a077d633e342aa0c prerequisite-patch-id: 9e4296261b608ee172060d04b3de431a5e370096 prerequisite-patch-id: 2b008e0e14a212072874ecb483d9c6844d161b08 prerequisite-patch-id: f5b692b89c997d828832e3ab27fffb8f770d7b6f prerequisite-patch-id: 851d6f4874aa24540db9d765275ae736e8b2955b prerequisite-patch-id: d3969c2fb7cd320eafebe63d7da270dac5a82fc9 prerequisite-patch-id: e1fc1478b7f75094d263ffc64a9f3528151831cf prerequisite-patch-id: 45fb53996a9f5993e03673c10eebf2834c58307f prerequisite-patch-id: 50ac1ddb52c3cce8b712036f212fdd67d7493112 -- 2.25.1 diff --git a/drivers/tty/serial/kgdboc.c b/drivers/tty/serial/kgdboc.c index 7aca0a67fc0b..a7a079ce2c5d 100644 --- a/drivers/tty/serial/kgdboc.c +++ b/drivers/tty/serial/kgdboc.c @@ -509,6 +509,8 @@ static struct kgdb_io kgdboc_earlycon_io_ops = { .is_console = true, }; +static bool kgdboc_earlycon_late_enable __initdata; + static int __init kgdboc_earlycon_init(char *opt) { struct console *con; @@ -529,7 +531,23 @@ static int __init kgdboc_earlycon_init(char *opt) console_unlock(); if (!con) { - pr_info("Couldn't find kgdb earlycon\n"); + /* + * If earlycon deferred its initialization then we also need to + * do that since there is no console at this point. We will + * only defer ourselves when kgdboc_earlycon has no arguments. + * This is because earlycon init is only deferred if there are + * no arguments to earlycon (we assume that a user who doesn't + * specify an earlycon driver won't know the right console name + * to put into kgdboc_earlycon and will let that auto-configure + * too). + */ + if (!kgdboc_earlycon_late_enable && + earlycon_acpi_spcr_enable && (!opt || !opt[0])) { + earlycon_kgdboc_late_enable = true; + pr_info("No suitable earlycon yet, will try later\n"); + } else { + pr_info("Couldn't find kgdb earlycon\n"); + } return 0; } @@ -545,6 +563,12 @@ static int __init kgdboc_earlycon_init(char *opt) } early_param("kgdboc_earlycon", kgdboc_earlycon_init); + +void __init kgdb_earlycon_late_init(void) +{ + if (kgdboc_earlycon_late_enable) + earlycon_kgdboc_init(NULL); +} #endif /* CONFIG_KGDB_SERIAL_CONSOLE */ module_init(init_kgdboc); diff --git a/include/linux/kgdb.h b/include/linux/kgdb.h index 77a3c519478a..02867a2f0eb4 100644 --- a/include/linux/kgdb.h +++ b/include/linux/kgdb.h @@ -227,6 +227,8 @@ extern int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt); extern void kgdb_arch_late(void); +extern void __init kgdb_earlycon_late_init(void); + /** * struct kgdb_arch - Describe architecture specific values. * @gdb_bpt_instr: The instruction to trigger a breakpoint. diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c index 2d74dcbca477..f066ef2bc615 100644 --- a/kernel/debug/debug_core.c +++ b/kernel/debug/debug_core.c @@ -963,11 +963,15 @@ void __weak kgdb_arch_late(void) { } +void __init __weak kgdb_earlycon_late_init(void) + void __init dbg_late_init(void) { dbg_is_early = false; if (kgdb_io_module_registered) kgdb_arch_late(); + else + kgdb_earlycon_late_init(); kdb_init(KDB_INIT_FULL); if (kgdb_io_module_registered && kgdb_break_asap)