From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: ARC-Seal: i=1; a=rsa-sha256; t=1525100199; cv=none; d=google.com; s=arc-20160816; b=cdzZgL/MPMyLchQAPtbG0wseTObzDy3Iu/0SXPJuirOgQBDcP8SEChDBEZeX7Tunb6 NiG7WGEzc5n9cjXe0ZH4ass8thXu5krKeB+OL2fka4KUm8BoU4Tb9YscARB5fviduMf4 ldUaTqtY2KClfkI0cIvfW669J9MChoYmVM95y96yyB0kQdde9krWBe8Qw7QYoHisG3qY wr3eSJ/eER5q6TA4bOTusQiuDP/4JyZsE7PDZGAfjuagpSqQ/ickXUzOc1a/2FtD8BYS r/JdoGEvESTIVTBN6OTO8vTYaFuXZrTwEvXB0U5MyQltDMA+ddRRzNRwg3oOXRJm5UKx Q19A== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=references:in-reply-to:message-id:date:subject:cc:to:from :dkim-signature:arc-authentication-results; bh=xU4YAUY7831TMun2OjClGonxrJ8++MJr7uL1RG44wpQ=; b=DfB+Og5G3pzsNTAjYTbydGvQqgFutGGkfk8drA6Xw15p3ZAt6WqPw4dBejX9QDwHJB owDs5fCjf7q24+e1OLprOnxoPCYf51PyOL1wfsQXuP6MI9GewwRmuPKTjEQ+zZLLJ25H qbunX1z+HKHK/JrtEVLoM+fRymhWeoNCoaLgcQYVogji2oEfBWFrq2N6c24fN6YGF9qk +MZgVNINP2wptfs2hTECwcVp0RrwFxvsKoMKqrHcS7rpUiHI4ifEXp9LgTvy6l4I+YA2 h3gZXaO/ffpVHDce0HjmWAoGwNtwzpEGJucKimwBO5fXGbm9202nnvq72DIxW0mSgghg 378A== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=d9QP7/xN; spf=pass (google.com: domain of npiggin@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=npiggin@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=d9QP7/xN; spf=pass (google.com: domain of npiggin@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=npiggin@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com X-Google-Smtp-Source: AB8JxZr40I6a3fgxdpV/dc/W6kuFzv1WIgzYJGjnH9bIvoIeHciJlXFUFeaRoUdN2OnE/Ufp03O0xg== From: Nicholas Piggin To: linuxppc-dev@lists.ozlabs.org Cc: Nicholas Piggin , Benjamin Herrenschmidt , Greg Kroah-Hartman , Jiri Slaby , linux-kernel@vger.kernel.org Subject: [PATCH 08/15] powerpc/powernv: implement opal_put_chars_atomic Date: Tue, 1 May 2018 00:55:51 +1000 Message-Id: <20180430145558.4308-9-npiggin@gmail.com> X-Mailer: git-send-email 2.17.0 In-Reply-To: <20180430145558.4308-1-npiggin@gmail.com> References: <20180430145558.4308-1-npiggin@gmail.com> X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1599183467019394764?= X-GMAIL-MSGID: =?utf-8?q?1599183467019394764?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: The RAW console does not need writes to be atomic, so relax opal_put_chars to be able to do partial writes, and implement an _atomic variant which does not take a spinlock. This API is used in xmon, so the less locking that is used, the better chance there is that a crash can be debugged. Cc: Benjamin Herrenschmidt Signed-off-by: Nicholas Piggin --- arch/powerpc/include/asm/opal.h | 1 + arch/powerpc/platforms/powernv/opal.c | 37 +++++++++++++++++++-------- drivers/tty/hvc/hvc_opal.c | 18 +++++++++---- 3 files changed, 41 insertions(+), 15 deletions(-) diff --git a/arch/powerpc/include/asm/opal.h b/arch/powerpc/include/asm/opal.h index bbff49fab0e5..5d7072411561 100644 --- a/arch/powerpc/include/asm/opal.h +++ b/arch/powerpc/include/asm/opal.h @@ -303,6 +303,7 @@ extern void opal_configure_cores(void); extern int opal_get_chars(uint32_t vtermno, char *buf, int count); extern int opal_put_chars(uint32_t vtermno, const char *buf, int total_len); +extern int opal_put_chars_atomic(uint32_t vtermno, const char *buf, int total_len); extern int opal_flush_console(uint32_t vtermno); extern void hvc_opal_init_early(void); diff --git a/arch/powerpc/platforms/powernv/opal.c b/arch/powerpc/platforms/powernv/opal.c index 55d4b1983110..bcdb90ada938 100644 --- a/arch/powerpc/platforms/powernv/opal.c +++ b/arch/powerpc/platforms/powernv/opal.c @@ -344,9 +344,9 @@ int opal_get_chars(uint32_t vtermno, char *buf, int count) return 0; } -int opal_put_chars(uint32_t vtermno, const char *data, int total_len) +static int __opal_put_chars(uint32_t vtermno, const char *data, int total_len, bool atomic) { - unsigned long flags; + unsigned long flags = 0 /* shut up gcc */; int written; __be64 olen; s64 rc; @@ -354,11 +354,8 @@ int opal_put_chars(uint32_t vtermno, const char *data, int total_len) if (!opal.entry) return -ENODEV; - /* We want put_chars to be atomic to avoid mangling of hvsi - * packets. To do that, we first test for room and return - * -EAGAIN if there isn't enough. - */ - spin_lock_irqsave(&opal_write_lock, flags); + if (atomic) + spin_lock_irqsave(&opal_write_lock, flags); rc = opal_console_write_buffer_space(vtermno, &olen); if (rc || be64_to_cpu(olen) < total_len) { /* Closed -> drop characters */ @@ -391,14 +388,18 @@ int opal_put_chars(uint32_t vtermno, const char *data, int total_len) written = be64_to_cpu(olen); if (written < total_len) { - /* Should not happen */ - pr_warn("atomic console write returned partial len=%d written=%d\n", total_len, written); + if (atomic) { + /* Should not happen */ + pr_warn("atomic console write returned partial " + "len=%d written=%d\n", total_len, written); + } if (!written) written = -EAGAIN; } out: - spin_unlock_irqrestore(&opal_write_lock, flags); + if (atomic) + spin_unlock_irqrestore(&opal_write_lock, flags); /* In the -EAGAIN case, callers loop, so we have to flush the console * here in case they have interrupts off (and we don't want to wait @@ -412,6 +413,22 @@ int opal_put_chars(uint32_t vtermno, const char *data, int total_len) return written; } +int opal_put_chars(uint32_t vtermno, const char *data, int total_len) +{ + return __opal_put_chars(vtermno, data, total_len, false); +} + +/* + * opal_put_chars_atomic will not perform partial-writes. Data will be + * atomically written to the terminal or not at all. This is not strictly + * true at the moment because console space can race with OPAL's console + * writes. + */ +int opal_put_chars_atomic(uint32_t vtermno, const char *data, int total_len) +{ + return __opal_put_chars(vtermno, data, total_len, true); +} + int opal_flush_console(uint32_t vtermno) { s64 rc; diff --git a/drivers/tty/hvc/hvc_opal.c b/drivers/tty/hvc/hvc_opal.c index af122ad7f06d..0a72f98ee082 100644 --- a/drivers/tty/hvc/hvc_opal.c +++ b/drivers/tty/hvc/hvc_opal.c @@ -183,9 +183,15 @@ static int hvc_opal_probe(struct platform_device *dev) return -ENOMEM; pv->proto = proto; hvc_opal_privs[termno] = pv; - if (proto == HV_PROTOCOL_HVSI) - hvsilib_init(&pv->hvsi, opal_get_chars, opal_put_chars, + if (proto == HV_PROTOCOL_HVSI) { + /* + * We want put_chars to be atomic to avoid mangling of + * hvsi packets. + */ + hvsilib_init(&pv->hvsi, + opal_get_chars, opal_put_chars_atomic, termno, 0); + } /* Instanciate now to establish a mapping index==vtermno */ hvc_instantiate(termno, termno, ops); @@ -376,8 +382,9 @@ void __init hvc_opal_init_early(void) else if (of_device_is_compatible(stdout_node,"ibm,opal-console-hvsi")) { hvc_opal_boot_priv.proto = HV_PROTOCOL_HVSI; ops = &hvc_opal_hvsi_ops; - hvsilib_init(&hvc_opal_boot_priv.hvsi, opal_get_chars, - opal_put_chars, index, 1); + hvsilib_init(&hvc_opal_boot_priv.hvsi, + opal_get_chars, opal_put_chars_atomic, + index, 1); /* HVSI, perform the handshake now */ hvsilib_establish(&hvc_opal_boot_priv.hvsi); pr_devel("hvc_opal: Found HVSI console\n"); @@ -409,7 +416,8 @@ void __init udbg_init_debug_opal_hvsi(void) hvc_opal_privs[index] = &hvc_opal_boot_priv; hvc_opal_boot_termno = index; udbg_init_opal_common(); - hvsilib_init(&hvc_opal_boot_priv.hvsi, opal_get_chars, opal_put_chars, + hvsilib_init(&hvc_opal_boot_priv.hvsi, + opal_get_chars, opal_put_chars_atomic, index, 1); hvsilib_establish(&hvc_opal_boot_priv.hvsi); } -- 2.17.0