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powerpc/rtas: Warn if per-function lock isn't held

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If the function descriptor has a populated lock member, then callers
are required to hold it across calls. Now that the firmware activation
sequence is appropriately guarded, we can warn when the requirement
isn't satisfied.

__do_enter_rtas_trace() gets reorganized a bit as a result of
performing the function descriptor lookup unconditionally now.

Reviewed-by: "Aneesh Kumar K.V (IBM)" <aneesh.kumar@kernel.org>
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231212-papr-sys_rtas-vs-lockdown-v6-8-e9eafd0c8c6c@linux.ibm.com
This commit is contained in:
Nathan Lynch 2023-12-12 11:01:55 -06:00 committed by Michael Ellerman
parent dc7637c402
commit e3681107bc
1 changed files with 10 additions and 13 deletions
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23
arch/powerpc/kernel/rtas.c
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@ -671,28 +671,25 @@ static void __do_enter_rtas(struct rtas_args *args)
static void __do_enter_rtas_trace(struct rtas_args *args)
{
const char *name = NULL;
const struct rtas_function *func = rtas_token_to_function(be32_to_cpu(args->token));
/*
* If there is a per-function lock, it must be held by the
* caller.
*/
if (func->lock)
lockdep_assert_held(func->lock);
if (args == &rtas_args)
lockdep_assert_held(&rtas_lock);
/*
* If the tracepoints that consume the function name aren't
* active, avoid the lookup.
*/
if ((trace_rtas_input_enabled() || trace_rtas_output_enabled())) {
const s32 token = be32_to_cpu(args->token);
const struct rtas_function *func = rtas_token_to_function(token);
name = func->name;
}
trace_rtas_input(args, name);
trace_rtas_input(args, func->name);
trace_rtas_ll_entry(args);
__do_enter_rtas(args);
trace_rtas_ll_exit(args);
trace_rtas_output(args, name);
trace_rtas_output(args, func->name);
}
static void do_enter_rtas(struct rtas_args *args)