On Thu, Sep 26, 2013 at 08:33:53PM -0400, Kevin O'Connor wrote:
On Wed, Sep 25, 2013 at 12:54:42PM +0300, Michael S. Tsirkin wrote:
Will be used to find RSDP there.
Signed-off-by: Michael S. Tsirkin mst@redhat.com
src/malloc.h | 1 + src/malloc.c | 19 ++++++++++++++++++- 2 files changed, 19 insertions(+), 1 deletion(-)
diff --git a/src/malloc.h b/src/malloc.h index af8a21d..feb8938 100644 --- a/src/malloc.h +++ b/src/malloc.h @@ -19,6 +19,7 @@ void *_malloc(struct zone_s *zone, u32 handle, u32 size, u32 align); int _free(void *data); u32 malloc_getspace(struct zone_s *zone); void *malloc_find(u32 handle); +void *malloc_find_fseg_pattern(void *pattern, unsigned pattern_size);
#define MALLOC_DEFAULT_HANDLE 0xFFFFFFFF // Minimum alignment of malloc'd memory diff --git a/src/malloc.c b/src/malloc.c index 281f41e..0f5fae7 100644 --- a/src/malloc.c +++ b/src/malloc.c @@ -12,7 +12,7 @@ #include "output.h" // dprintf #include "stacks.h" // wait_preempt #include "std/optionrom.h" // OPTION_ROM_ALIGN -#include "string.h" // memset +#include "string.h" // memset, memcmp
// Information on a reserved area. struct allocinfo_s { @@ -273,6 +273,23 @@ _free(void *data) return 0; }
+// Find the data block in zone matching a given pattern. +void *malloc_find_fseg_pattern(void *pattern, unsigned pattern_size) +{
- extern u8 zonefseg_start[], zonefseg_end[];
- unsigned space = zonefseg_end - zonefseg_start;
- int off;
- if (space < pattern_size)
return NULL;- for (off = 0; off < space - pattern_size; ++off) {
if (!memcmp(zonefseg_start + off, pattern, pattern_size))return zonefseg_start + off;- }
- return NULL;
+}
This shouldn't be in malloc.c - it's not part of the core memory allocation system. Either scan the whole of 0xf0000-0x100000, use extern zonefseg_end/start in another file, or scan the allocations made in romfile-loader.
BTW ACPI spec says 0xe0000 and not 0xf0000:
5.2.5.1 Finding the RSDP on IA-PC Systems OSPM finds the Root System Description Pointer (RSDP) structure by searching physical memory ranges on 16-byte boundaries for a valid Root System Description Pointer structure signature and checksum match as follows: • The first 1 KB of the Extended BIOS Data Area (EBDA). For EISA or MCA systems, the EBDA can be found in the two-byte location 40:0Eh on the BIOS data area. • The BIOS read-only memory space between 0E0000h and 0FFFFFh.
Also, this shouldn't scan every byte for the pattern. It should scan on 16 byte boundaries and do the acpi checksum check. See the code in fw/biostable.c:copy_acpi_rsdp as an example. Nothing stops something else from allocating ram which happens to have an rsdp signature in it. It's unlikely, but not worth the risk.
The rest of the series looks okay to me.
-Kevin