Hi,
attached patch reworks the payload handling with CBFS (ie. selfboot).
We use a bounce buffer (both in CBFS and older) to keep coreboot running
while allowing the payload to use the same memory region, and this is a
tricky part of our code.
Assumptions in the code are:
The bounce buffer is at least 2x coreboot_ram size (lb_end - lb_start),
with the first half being the shadow region that the payload's data
lives in (exactly the bytes that cover the area of coreboot_ram), while
the second half exists to host a copy of coreboot while copying.
The change leads to the following behaviour:
At least 2x coreboot_ram size is looked for.
The area before the bounce buffer is assumed to be reasonably free (but
this isn't validated)
Payload segments that conflict with coreboot_ram are loaded to the
bounce buffer, probably using the memory before it, and filling up more
than coreboot_ram bytes there
Right after copying, the "out of area" bytes are copied to their final
location (around coreboot_ram).
I want to revisit the prefix/suffix calculation, as I'm not 100% sure
that it's doing the right thing (those copy operations should copy
_exactly_ the necessary set of bytes, nothing more), review is welcome
(look for "prefix" and "suffix" in selfboot.c)
The code is runtime tested on qemu-x86 (after cranking up the STACK_SIZE
to >16kb, so lzma could run), with the following scenarios:
RAMBASE = 0x4000, payload starting at 0x00100000
(no collision between coreboot_ram and payload)
RAMBASE = 0x00100000, payload starting at 0x00100000
(RAMBASE below or at payload starting address, this worked before)
RAMBASE = 0x00101000, payload starting at 0x00100000
(RAMBASE above payload starting address, this fails without this patch.
AMD boards were notorious with that one)
Pending the review of the prefix/suffix calculations (by me and
hopefully others), this is
Signed-off-by: Patrick Georgi <[email protected]>
Once this is in, there are no CBFS issues that I know of, and hence I
propose to eliminate non-CBFS support in the tree soonish after that
patch is in.
I have some older patch for this, but it will likely not apply anymore,
but I can update it.
Opinions?
Regards,
Patrick
Index: src/boot/selfboot.c
===================================================================
--- src/boot/selfboot.c (Revision 4691)
+++ src/boot/selfboot.c (Arbeitskopie)
@@ -423,14 +423,13 @@
{
struct segment *ptr;
- unsigned long required_bounce_size = lb_end - lb_start;
+ unsigned long bounce_high = lb_end;
for(ptr = head->next; ptr != head; ptr = ptr->next) {
if (!overlaps_coreboot(ptr)) continue;
- unsigned long bounce = ptr->s_dstaddr + ptr->s_memsz - lb_start;
- if (bounce > required_bounce_size)
- required_bounce_size = bounce;
+ if (ptr->s_dstaddr + ptr->s_memsz > bounce_high)
+ bounce_high = ptr->s_dstaddr + ptr->s_memsz;
}
- get_bounce_buffer(mem, required_bounce_size);
+ get_bounce_buffer(mem, bounce_high - lb_start);
if (!bounce_buffer) {
printk_err("Could not find a bounce buffer...\n");
return 0;
@@ -502,6 +501,24 @@
/* Zero the extra bytes */
memset(middle, 0, end - middle);
}
+ /* Copy the data that's outside the area that shadows coreboot_ram */
+ printk_debug("dest %lx, end %lx, bouncebuffer %lx\n", dest, end, bounce_buffer);
+ if ((unsigned long)end > bounce_buffer) {
+ if ((unsigned long)dest < bounce_buffer) {
+ unsigned long from = dest;
+ unsigned long to = lb_start-(bounce_buffer-(unsigned long)dest);
+ unsigned long amount = bounce_buffer-(unsigned long)dest;
+ printk_debug("move prefix around: from %lx, to %lx, amount: %lx\n", from, to, amount);
+ memcpy(to, from, amount);
+ }
+ if ((unsigned long)end > bounce_buffer + (lb_end - lb_start)) {
+ unsigned long from = bounce_buffer + bounce_size;
+ unsigned long to = lb_end;
+ unsigned long amount = end - (bounce_buffer + bounce_size);
+ printk_debug("move suffix around: from %lx, to %lx, amount: %lx\n", from, to, amount);
+ memcpy(to, from, amount);
+ }
+ }
}
}
return 1;
--
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