Commit 05bd1c85 authored Nov 18, 2022 by Nathan Lynch Committed by zhaoxiaoqiang11 Aug 14, 2023

powerpc/rtas: avoid device tree lookups in rtas_os_term()

stable inclusion
from stable-v5.10.163
commit f2167f10fcca68ab9ae3f8d94d2c704c5541ac69
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7PJ9N

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f2167f10fcca68ab9ae3f8d94d2c704c5541ac69



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

[ Upstream commit ed2213bf ]

rtas_os_term() is called during panic. Its behavior depends on a couple
of conditions in the /rtas node of the device tree, the traversal of
which entails locking and local IRQ state changes. If the kernel panics
while devtree_lock is held, rtas_os_term() as currently written could
hang.

Instead of discovering the relevant characteristics at panic time,
cache them in file-static variables at boot. Note the lookup for
"ibm,extended-os-term" is converted to of_property_read_bool() since it
is a boolean property, not an RTAS function token.

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Andrew Donnellan <ajd@linux.ibm.com>
[mpe: Incorporate suggested change from Nick]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221118150751.469393-4-nathanl@linux.ibm.com


Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: zhaoxiaoqiang11 <zhaoxiaoqiang11@jd.com>

parent 7ff985ed

arch/powerpc/kernel/rtas.c

+10 −3

Original line number	Diff line number	Diff line
		@@ -715,6 +715,7 @@ void __noreturn rtas_halt(void)

		/* Must be in the RMO region, so we place it here */
		static char rtas_os_term_buf[2048];
		static s32 ibm_os_term_token = RTAS_UNKNOWN_SERVICE;

		void rtas_os_term(char *str)
		{
		@@ -726,14 +727,13 @@ void rtas_os_term(char *str)
		* this property may terminate the partition which we want to avoid
		* since it interferes with panic_timeout.
		*/
		if (RTAS_UNKNOWN_SERVICE == rtas_token("ibm,os-term") \|\|
		RTAS_UNKNOWN_SERVICE == rtas_token("ibm,extended-os-term"))
		if (ibm_os_term_token == RTAS_UNKNOWN_SERVICE)
		return;

		snprintf(rtas_os_term_buf, 2048, "OS panic: %s", str);

		do {
		status = rtas_call(rtas_token("ibm,os-term"), 1, 1, NULL,
		status = rtas_call(ibm_os_term_token, 1, 1, NULL,
		__pa(rtas_os_term_buf));
		} while (rtas_busy_delay(status));

		@@ -1267,6 +1267,13 @@ void __init rtas_initialize(void)
		no_entry = of_property_read_u32(rtas.dev, "linux,rtas-entry", &entry);
		rtas.entry = no_entry ? rtas.base : entry;

		/*
		* Discover these now to avoid device tree lookups in the
		* panic path.
		*/
		if (of_property_read_bool(rtas.dev, "ibm,extended-os-term"))
		ibm_os_term_token = rtas_token("ibm,os-term");

		/* If RTAS was found, allocate the RMO buffer for it and look for
		* the stop-self token if any
		*/