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firmware: google: memconsole: Adapt to new coreboot ring buffer format
The upstream coreboot implementation of memconsole was enhanced from a single-boot console to a persistent ring buffer (https://review.coreboot.org/#/c/18301). This patch changes the kernel memconsole driver to be able to read the new format in all cases. Signed-off-by: Julius Werner <jwerner@chromium.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -26,19 +26,50 @@
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/* CBMEM firmware console log descriptor. */
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struct cbmem_cons {
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u32 buffer_size;
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u32 buffer_cursor;
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u8 buffer_body[0];
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u32 size;
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u32 cursor;
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u8 body[0];
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} __packed;
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#define CURSOR_MASK ((1 << 28) - 1)
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#define OVERFLOW (1 << 31)
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static struct cbmem_cons __iomem *cbmem_console;
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/*
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* The cbmem_console structure is read again on every access because it may
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* change at any time if runtime firmware logs new messages. This may rarely
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* lead to race conditions where the firmware overwrites the beginning of the
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* ring buffer with more lines after we have already read |cursor|. It should be
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* rare and harmless enough that we don't spend extra effort working around it.
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*/
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static ssize_t memconsole_coreboot_read(char *buf, loff_t pos, size_t count)
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{
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return memory_read_from_buffer(buf, count, &pos,
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cbmem_console->buffer_body,
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min(cbmem_console->buffer_cursor,
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cbmem_console->buffer_size));
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u32 cursor = cbmem_console->cursor & CURSOR_MASK;
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u32 flags = cbmem_console->cursor & ~CURSOR_MASK;
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u32 size = cbmem_console->size;
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struct seg { /* describes ring buffer segments in logical order */
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u32 phys; /* physical offset from start of mem buffer */
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u32 len; /* length of segment */
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} seg[2] = { {0}, {0} };
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size_t done = 0;
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int i;
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if (flags & OVERFLOW) {
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if (cursor > size) /* Shouldn't really happen, but... */
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cursor = 0;
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seg[0] = (struct seg){.phys = cursor, .len = size - cursor};
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seg[1] = (struct seg){.phys = 0, .len = cursor};
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} else {
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seg[0] = (struct seg){.phys = 0, .len = min(cursor, size)};
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}
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for (i = 0; i < ARRAY_SIZE(seg) && count > done; i++) {
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done += memory_read_from_buffer(buf + done, count - done, &pos,
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cbmem_console->body + seg[i].phys, seg[i].len);
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pos -= seg[i].len;
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}
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return done;
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}
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static int memconsole_coreboot_init(phys_addr_t physaddr)
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@ -51,7 +82,7 @@ static int memconsole_coreboot_init(phys_addr_t physaddr)
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return -ENOMEM;
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cbmem_console = memremap(physaddr,
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tmp_cbmc->buffer_size + sizeof(*cbmem_console),
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tmp_cbmc->size + sizeof(*cbmem_console),
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MEMREMAP_WB);
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memunmap(tmp_cbmc);
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