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device-tree: add re-randomization helper function

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When the system reboots, the rng-seed that the FDT has should be
re-randomized, so that the new boot gets a new seed. Several
architectures require this functionality, so export a function for
injecting a new seed into the given FDT.

Cc: Alistair Francis <alistair.francis@wdc.com>
Cc: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-id: 20221025004327.568476-3-Jason@zx2c4.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
Jason A. Donenfeld 2022-10-25 02:43:18 +02:00 committed by Peter Maydell
parent 7966d70f6f
commit e1e618b9a0
2 changed files with 30 additions and 0 deletions
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9
include/sysemu/device_tree.h
View file

@ -197,6 +197,15 @@ int qemu_fdt_setprop_sized_cells_from_array(void *fdt,
qdt_tmp); \
})
/**
* qemu_fdt_randomize_seeds:
* @fdt: device tree blob
*
* Re-randomize all "rng-seed" properties with new seeds.
*/
void qemu_fdt_randomize_seeds(void *fdt);
#define FDT_PCI_RANGE_RELOCATABLE 0x80000000
#define FDT_PCI_RANGE_PREFETCHABLE 0x40000000
#define FDT_PCI_RANGE_ALIASED 0x20000000

21
softmmu/device_tree.c
View file

@ -22,6 +22,7 @@
#include "qemu/option.h"
#include "qemu/bswap.h"
#include "qemu/cutils.h"
#include "qemu/guest-random.h"
#include "sysemu/device_tree.h"
#include "hw/loader.h"
#include "hw/boards.h"
@ -680,3 +681,23 @@ void hmp_dumpdtb(Monitor *mon, const QDict *qdict)
info_report("dtb dumped to %s", filename);
}
void qemu_fdt_randomize_seeds(void *fdt)
{
int noffset, poffset, len;
const char *name;
uint8_t *data;
for (noffset = fdt_next_node(fdt, 0, NULL);
noffset >= 0;
noffset = fdt_next_node(fdt, noffset, NULL)) {
for (poffset = fdt_first_property_offset(fdt, noffset);
poffset >= 0;
poffset = fdt_next_property_offset(fdt, poffset)) {
data = (uint8_t *)fdt_getprop_by_offset(fdt, poffset, &name, &len);
if (!data || strcmp(name, "rng-seed"))
continue;
qemu_guest_getrandom_nofail(data, len);
}
}
}