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From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Vasily Gorbik <gor@linux.ibm.com>,
	Sven Schnelle <svens@linux.ibm.com>,
	Heiko Carstens <hca@linux.ibm.com>,
	Sasha Levin <sashal@kernel.org>,
	linux-s390@vger.kernel.org
Subject: [PATCH AUTOSEL 4.14 05/11] s390/entry: save the caller of psw_idle
Date: Mon, 19 Apr 2021 16:45:30 -0400	[thread overview]
Message-ID: <20210419204536.6924-5-sashal@kernel.org> (raw)
In-Reply-To: <20210419204536.6924-1-sashal@kernel.org>

From: Vasily Gorbik <gor@linux.ibm.com>

[ Upstream commit a994eddb947ea9ebb7b14d9a1267001699f0a136 ]

Currently psw_idle does not allocate a stack frame and does not
save its r14 and r15 into the save area. Even though this is valid from
call ABI point of view, because psw_idle does not make any calls
explicitly, in reality psw_idle is an entry point for controlled
transition into serving interrupts. So, in practice, psw_idle stack
frame is analyzed during stack unwinding. Depending on build options
that r14 slot in the save area of psw_idle might either contain a value
saved by previous sibling call or complete garbage.

  [task    0000038000003c28] do_ext_irq+0xd6/0x160
  [task    0000038000003c78] ext_int_handler+0xba/0xe8
  [task   *0000038000003dd8] psw_idle_exit+0x0/0x8 <-- pt_regs
 ([task    0000038000003dd8] 0x0)
  [task    0000038000003e10] default_idle_call+0x42/0x148
  [task    0000038000003e30] do_idle+0xce/0x160
  [task    0000038000003e70] cpu_startup_entry+0x36/0x40
  [task    0000038000003ea0] arch_call_rest_init+0x76/0x80

So, to make a stacktrace nicer and actually point for the real caller of
psw_idle in this frequently occurring case, make psw_idle save its r14.

  [task    0000038000003c28] do_ext_irq+0xd6/0x160
  [task    0000038000003c78] ext_int_handler+0xba/0xe8
  [task   *0000038000003dd8] psw_idle_exit+0x0/0x6 <-- pt_regs
 ([task    0000038000003dd8] arch_cpu_idle+0x3c/0xd0)
  [task    0000038000003e10] default_idle_call+0x42/0x148
  [task    0000038000003e30] do_idle+0xce/0x160
  [task    0000038000003e70] cpu_startup_entry+0x36/0x40
  [task    0000038000003ea0] arch_call_rest_init+0x76/0x80

Reviewed-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/s390/kernel/entry.S | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
index e928c2af6a10..dd470f45c4b9 100644
--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -967,6 +967,7 @@ ENTRY(ext_int_handler)
  * Load idle PSW. The second "half" of this function is in .Lcleanup_idle.
  */
 ENTRY(psw_idle)
+	stg	%r14,(__SF_GPRS+8*8)(%r15)
 	stg	%r3,__SF_EMPTY(%r15)
 	larl	%r1,.Lpsw_idle_lpsw+4
 	stg	%r1,__SF_EMPTY+8(%r15)
-- 
2.30.2


  parent reply	other threads:[~2021-04-19 20:49 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-19 20:45 [PATCH AUTOSEL 4.14 01/11] HID: alps: fix error return code in alps_input_configured() Sasha Levin
2021-04-19 20:45 ` [PATCH AUTOSEL 4.14 02/11] HID: wacom: Assign boolean values to a bool variable Sasha Levin
2021-04-19 20:45 ` [PATCH AUTOSEL 4.14 03/11] ARM: dts: Fix swapped mmc order for omap3 Sasha Levin
2021-04-19 20:45 ` [PATCH AUTOSEL 4.14 04/11] net: geneve: check skb is large enough for IPv4/IPv6 header Sasha Levin
2021-04-19 20:45 ` Sasha Levin [this message]
2021-04-19 20:45 ` [PATCH AUTOSEL 4.14 06/11] xen-netback: Check for hotplug-status existence before watching Sasha Levin
2021-04-19 20:45 ` [PATCH AUTOSEL 4.14 07/11] cavium/liquidio: Fix duplicate argument Sasha Levin
2021-04-19 20:45 ` [PATCH AUTOSEL 4.14 08/11] i2c: mv64xxx: Fix random system lock caused by runtime PM Sasha Levin
2021-04-19 20:45 ` [PATCH AUTOSEL 4.14 09/11] ia64: fix discontig.c section mismatches Sasha Levin
2021-04-19 20:45 ` [PATCH AUTOSEL 4.14 10/11] ia64: tools: remove duplicate definition of ia64_mf() on ia64 Sasha Levin
2021-04-19 20:45 ` [PATCH AUTOSEL 4.14 11/11] readdir: make sure to verify directory entry for legacy interfaces too Sasha Levin

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