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Subject[PATCH 3.8 79/81] powerpc/le: Ensure that the 'stop-self' RTAS token is handled correctly
Date
3.8.13.20 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Tony Breeds <tony@bakeyournoodle.com>

commit 41dd03a94c7d408d2ef32530545097f7d1befe5c upstream.

Currently we're storing a host endian RTAS token in
rtas_stop_self_args.token. We then pass that directly to rtas. This is
fine on big endian however on little endian the token is not what we
expect.

This will typically result in hitting:
panic("Alas, I survived.\n");

To fix this we always use the stop-self token in host order and always
convert it to be32 before passing this to rtas.

Signed-off-by: Tony Breeds <tony@bakeyournoodle.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
arch/powerpc/platforms/pseries/hotplug-cpu.c | 22 +++++++++++-----------
1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/hotplug-cpu.c b/arch/powerpc/platforms/pseries/hotplug-cpu.c
index a389562..3f0cfca 100644
--- a/arch/powerpc/platforms/pseries/hotplug-cpu.c
+++ b/arch/powerpc/platforms/pseries/hotplug-cpu.c
@@ -34,12 +34,7 @@
#include "offline_states.h"

/* This version can't take the spinlock, because it never returns */
-static struct rtas_args rtas_stop_self_args = {
- .token = RTAS_UNKNOWN_SERVICE,
- .nargs = 0,
- .nret = 1,
- .rets = &rtas_stop_self_args.args[0],
-};
+static int rtas_stop_self_token = RTAS_UNKNOWN_SERVICE;

static DEFINE_PER_CPU(enum cpu_state_vals, preferred_offline_state) =
CPU_STATE_OFFLINE;
@@ -92,15 +87,20 @@ void set_default_offline_state(int cpu)

static void rtas_stop_self(void)
{
- struct rtas_args *args = &rtas_stop_self_args;
+ struct rtas_args args = {
+ .token = cpu_to_be32(rtas_stop_self_token),
+ .nargs = 0,
+ .nret = 1,
+ .rets = &args.args[0],
+ };

local_irq_disable();

- BUG_ON(args->token == RTAS_UNKNOWN_SERVICE);
+ BUG_ON(rtas_stop_self_token == RTAS_UNKNOWN_SERVICE);

printk("cpu %u (hwid %u) Ready to die...\n",
smp_processor_id(), hard_smp_processor_id());
- enter_rtas(__pa(args));
+ enter_rtas(__pa(&args));

panic("Alas, I survived.\n");
}
@@ -383,10 +383,10 @@ static int __init pseries_cpu_hotplug_init(void)
}
}

- rtas_stop_self_args.token = rtas_token("stop-self");
+ rtas_stop_self_token = rtas_token("stop-self");
qcss_tok = rtas_token("query-cpu-stopped-state");

- if (rtas_stop_self_args.token == RTAS_UNKNOWN_SERVICE ||
+ if (rtas_stop_self_token == RTAS_UNKNOWN_SERVICE ||
qcss_tok == RTAS_UNKNOWN_SERVICE) {
printk(KERN_INFO "CPU Hotplug not supported by firmware "
"- disabling.\n");
--
1.8.3.2


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