PAPR specifies that ibm,open-errinjct has a unique return-cell layout:
rets[0] = injection session token (output parameter)
rets[1] = status code
This differs from every other RTAS call, where:
rets[0] = status code
rets[1..] = output parameters
As a result, the existing rtas_call() convention — return value is the
RTAS status, outputs[] receives the non-status output values — must be
preserved while correctly extracting status from rets[1] for this one
call.
Add rtas_token_is_open_errinjct() and rtas_status_from_args() helpers.
rtas_status_from_args() selects the correct status cell based on the
token, and the output-copy loop in rtas_call() is updated so that for
ibm,open-errinjct:
rtas_call() return = rets[1] (RTAS status)
outputs[0] = rets[0] (session token)
For all other calls the behaviour is unchanged: return value is rets[0]
and outputs[] receives rets[1..nret-1].
The sys_rtas userspace path is not modified: copy_to_user() still
copies raw RTAS return cells (rets[0..nret-1]) to userspace.
Callers passing a single output int (nret == 2) are safe because we
write at most nret-1 values into outputs[], never all nret cells.
Also move the '/* A -1 return code...*/' comment to immediately precede
the if (ret == -1) check it describes, and remove the redundant stale
else branch that re-assigned ret.
Reference: OpenPOWER PAPR documentation
https://files.openpower.foundation/s/XFgfMaqLMD5Bcm8
Signed-off-by: Narayana Murty N <[email protected]>
---
arch/powerpc/kernel/rtas.c | 51 ++++++++++++++++++++++++++++++++------
1 file changed, 44 insertions(+), 7 deletions(-)
diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c
index 8d81c1e7a8db..27d53f34494d 100644
--- a/arch/powerpc/kernel/rtas.c
+++ b/arch/powerpc/kernel/rtas.c
@@ -1117,6 +1117,29 @@ static bool token_is_restricted_errinjct(s32 token)
token == rtas_function_token(RTAS_FN_IBM_ERRINJCT);
}
+/**
+ * rtas_token_is_open_errinjct() - Test whether @token identifies
ibm,open-errinjct.
+ */
+static bool rtas_token_is_open_errinjct(int token)
+{
+ return token == rtas_function_token(RTAS_FN_IBM_OPEN_ERRINJCT);
+}
+
+/**
+ * rtas_status_from_args() - Extract the RTAS status code from a completed
+ * call's return-cell array.
+ *
+ * For ibm,open-errinjct the status lives in rets[1]; for every other
+ * RTAS function it lives in rets[0].
+ */
+static int rtas_status_from_args(int token, struct rtas_args *args, int nret)
+{
+ if (rtas_token_is_open_errinjct(token) && nret > 1)
+ return be32_to_cpu(args->rets[1]);
+
+ return nret > 0 ? be32_to_cpu(args->rets[0]) : 0;
+}
+
/**
* rtas_call() - Invoke an RTAS firmware function.
* @token: Identifies the function being invoked.
@@ -1213,15 +1236,29 @@ int rtas_call(int token, int nargs, int nret, int
*outputs, ...)
va_rtas_call_unlocked(args, token, nargs, nret, list);
va_end(list);
- /* A -1 return code indicates that the last command couldn't
- be completed due to a hardware error. */
- if (be32_to_cpu(args->rets[0]) == -1)
+ ret = rtas_status_from_args(token, args, nret);
+
+ /*
+ * A -1 return code indicates that the last command couldn't
+ * be completed due to a hardware error.
+ */
+ if (ret == -1)
buff_copy = __fetch_rtas_last_error(NULL);
- if (nret > 1 && outputs != NULL)
- for (i = 0; i < nret-1; ++i)
- outputs[i] = be32_to_cpu(args->rets[i + 1]);
- ret = (nret > 0) ? be32_to_cpu(args->rets[0]) : 0;
+ if (nret > 1 && outputs != NULL) {
+ if (rtas_token_is_open_errinjct(token)) {
+ /*
+ * ibm,open-errinjct: rets[0]=session token,
rets[1]=status.
+ * Expose session token in outputs[0]; skip rets[1]
(status).
+ */
+ outputs[0] = be32_to_cpu(args->rets[0]);
+ for (i = 1; i < nret - 1; ++i)
+ outputs[i] = be32_to_cpu(args->rets[i + 1]);
+ } else {
+ for (i = 0; i < nret - 1; ++i)
+ outputs[i] = be32_to_cpu(args->rets[i + 1]);
+ }
+ }
lockdep_unpin_lock(&rtas_lock, cookie);
raw_spin_unlock_irqrestore(&rtas_lock, flags);
--
2.54.0
