linux,sml-base holds the address of a buffer with the TPM log. This
buffer may become invalid after a kexec. To avoid accessing an invalid
address or corrupted buffer, embed the whole TPM log in the device tree
property linux,sml-log. This helps to protect the log since it is
properly carried across a kexec soft reboot with both of the kexec
syscalls.
Avoid having the firmware ingest the whole TPM log when calling
prom_setprop but only create the linux,sml-log property as a place holder.
Insert the actual TPM log during the tree flattening phase.
Fixes: 4a727429abec ("PPC64: Add support for instantiating SML from Open Firmware")
Suggested-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Signed-off-by: Stefan Berger <stefanb@xxxxxxxxxxxxx>
---
arch/powerpc/kernel/prom_init.c | 27 +++++++++++++++++++--------
1 file changed, 19 insertions(+), 8 deletions(-)
diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c
index e67effdba85c..6f7ca72013c2 100644
--- a/arch/powerpc/kernel/prom_init.c
+++ b/arch/powerpc/kernel/prom_init.c
@@ -211,6 +211,8 @@ static cell_t __prombss regbuf[1024];
static bool __prombss rtas_has_query_cpu_stopped;
+static u64 __prombss sml_base;
+static u32 __prombss sml_size;
/*
* Error results ... some OF calls will return "-1" on error, some
@@ -1954,17 +1956,15 @@ static void __init prom_instantiate_sml(void)
}
prom_printf(" done\n");
- reserve_mem(base, size);
-
- prom_setprop(ibmvtpm_node, "/vdevice/vtpm", "linux,sml-base",
- &base, sizeof(base));
- prom_setprop(ibmvtpm_node, "/vdevice/vtpm", "linux,sml-size",
- &size, sizeof(size));
-
- prom_debug("sml base = 0x%llx\n", base);
+ /* Add property now, defer adding log to tree flattening phase */
+ prom_setprop(ibmvtpm_node, "/vdevice/vtpm", "linux,sml-log",
+ NULL, 0);
prom_debug("sml size = 0x%x\n", size);
prom_debug("prom_instantiate_sml: end...\n");
+
+ sml_base = base;
+ sml_size = size;
}
/*
@@ -2645,6 +2645,17 @@ static void __init scan_dt_build_struct(phandle node, unsigned long *mem_start,
}
prev_name = sstart + soff;
+ if (!prom_strcmp("linux,sml-log", pname)) {
+ /* push property head */
+ dt_push_token(OF_DT_PROP, mem_start, mem_end);
+ dt_push_token(sml_size, mem_start, mem_end);
+ dt_push_token(soff, mem_start, mem_end);
+ /* push property content */
+ valp = make_room(mem_start, mem_end, sml_size, 1);
+ memcpy(valp, (void *)sml_base, sml_size);
+ *mem_start = ALIGN(*mem_start, 4);
+ continue;
+ }
/* get length */
l = call_prom("getproplen", 2, 1, node, pname);
--
2.43.0
