caf69ba627
memory_return_from_buffer returns a signed value, so ret should be ssize_t. Fixes the following issue reported by David Binderman: [linux-3.15/arch/powerpc/platforms/powernv/opal-msglog.c:65]: (style) Checking if unsigned variable 'ret' is less than zero. [linux-3.15/arch/powerpc/platforms/powernv/opal-msglog.c:82]: (style) Checking if unsigned variable 'ret' is less than zero. Local variable "ret" is of type size_t. This is always unsigned, so it is pointless to check if it is less than zero. https://bugzilla.kernel.org/show_bug.cgi?id=77551 Fixing this exposes a real bug for the case where the entire count bytes is successfully read from the POS_WRAP case. The second memory_read_from_buffer will return EINVAL, causing the entire read to return EINVAL to userspace, despite the data being copied correctly. The fix is to test for the case where the data has been read and return early. Signed-off-by: Joel Stanley <joel@jms.id.au> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
124 lines
2.9 KiB
C
124 lines
2.9 KiB
C
/*
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* PowerNV OPAL in-memory console interface
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*
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* Copyright 2014 IBM Corp.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <asm/io.h>
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#include <asm/opal.h>
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#include <linux/debugfs.h>
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#include <linux/of.h>
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#include <linux/types.h>
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#include <asm/barrier.h>
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/* OPAL in-memory console. Defined in OPAL source at core/console.c */
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struct memcons {
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__be64 magic;
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#define MEMCONS_MAGIC 0x6630696567726173L
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__be64 obuf_phys;
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__be64 ibuf_phys;
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__be32 obuf_size;
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__be32 ibuf_size;
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__be32 out_pos;
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#define MEMCONS_OUT_POS_WRAP 0x80000000u
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#define MEMCONS_OUT_POS_MASK 0x00ffffffu
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__be32 in_prod;
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__be32 in_cons;
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};
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static ssize_t opal_msglog_read(struct file *file, struct kobject *kobj,
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struct bin_attribute *bin_attr, char *to,
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loff_t pos, size_t count)
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{
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struct memcons *mc = bin_attr->private;
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const char *conbuf;
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ssize_t ret;
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size_t first_read = 0;
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uint32_t out_pos, avail;
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if (!mc)
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return -ENODEV;
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out_pos = be32_to_cpu(ACCESS_ONCE(mc->out_pos));
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/* Now we've read out_pos, put a barrier in before reading the new
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* data it points to in conbuf. */
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smp_rmb();
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conbuf = phys_to_virt(be64_to_cpu(mc->obuf_phys));
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/* When the buffer has wrapped, read from the out_pos marker to the end
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* of the buffer, and then read the remaining data as in the un-wrapped
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* case. */
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if (out_pos & MEMCONS_OUT_POS_WRAP) {
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out_pos &= MEMCONS_OUT_POS_MASK;
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avail = be32_to_cpu(mc->obuf_size) - out_pos;
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ret = memory_read_from_buffer(to, count, &pos,
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conbuf + out_pos, avail);
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if (ret < 0)
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goto out;
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first_read = ret;
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to += first_read;
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count -= first_read;
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pos -= avail;
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if (count <= 0)
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goto out;
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}
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/* Sanity check. The firmware should not do this to us. */
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if (out_pos > be32_to_cpu(mc->obuf_size)) {
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pr_err("OPAL: memory console corruption. Aborting read.\n");
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return -EINVAL;
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}
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ret = memory_read_from_buffer(to, count, &pos, conbuf, out_pos);
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if (ret < 0)
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goto out;
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ret += first_read;
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out:
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return ret;
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}
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static struct bin_attribute opal_msglog_attr = {
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.attr = {.name = "msglog", .mode = 0444},
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.read = opal_msglog_read
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};
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void __init opal_msglog_init(void)
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{
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u64 mcaddr;
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struct memcons *mc;
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if (of_property_read_u64(opal_node, "ibm,opal-memcons", &mcaddr)) {
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pr_warn("OPAL: Property ibm,opal-memcons not found, no message log\n");
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return;
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}
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mc = phys_to_virt(mcaddr);
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if (!mc) {
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pr_warn("OPAL: memory console address is invalid\n");
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return;
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}
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if (be64_to_cpu(mc->magic) != MEMCONS_MAGIC) {
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pr_warn("OPAL: memory console version is invalid\n");
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return;
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}
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opal_msglog_attr.private = mc;
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if (sysfs_create_bin_file(opal_kobj, &opal_msglog_attr) != 0)
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pr_warn("OPAL: sysfs file creation failed\n");
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}
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