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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	stable@vger.kernel.org, afzal mohammed <afzal.mohd.ma@gmail.com>,
	Vladimir Murzin <vladimir.murzin@arm.com>,
	Russell King <rmk+kernel@armlinux.org.uk>,
	Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.19 27/79] ARM: 8926/1: v7m: remove register save to stack before svc
Date: Fri,  8 Nov 2019 19:50:07 +0100
Message-ID: <20191108174800.916142823@linuxfoundation.org> (raw)
In-Reply-To: <20191108174745.495640141@linuxfoundation.org>

From: afzal mohammed <afzal.mohd.ma@gmail.com>

[ Upstream commit 2ecb287998a47cc0a766f6071f63bc185f338540 ]

r0-r3 & r12 registers are saved & restored, before & after svc
respectively. Intention was to preserve those registers across thread to
handler mode switch.

On v7-M, hardware saves the register context upon exception in AAPCS
complaint way. Restoring r0-r3 & r12 is done from stack location where
hardware saves it, not from the location on stack where these registers
were saved.

To clarify, on stm32f429 discovery board:

1. before svc, sp - 0x90009ff8
2. r0-r3,r12 saved to 0x90009ff8 - 0x9000a00b
3. upon svc, h/w decrements sp by 32 & pushes registers onto stack
4. after svc,  sp - 0x90009fd8
5. r0-r3,r12 restored from 0x90009fd8 - 0x90009feb

Above means r0-r3,r12 is not restored from the location where they are
saved, but since hardware pushes the registers onto stack, the registers
are restored correctly.

Note that during register saving to stack (step 2), it goes past
0x9000a000. And it seems, based on objdump, there are global symbols
residing there, and it perhaps can cause issues on a non-XIP Kernel
(on XIP, data section is setup later).

Based on the analysis above, manually saving registers onto stack is at
best no-op and at worst can cause data section corruption. Hence remove
storing of registers onto stack before svc.

Fixes: b70cd406d7fe ("ARM: 8671/1: V7M: Preserve registers across switch from Thread to Handler mode")
Signed-off-by: afzal mohammed <afzal.mohd.ma@gmail.com>
Acked-by: Vladimir Murzin <vladimir.murzin@arm.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/arm/mm/proc-v7m.S | 1 -
 1 file changed, 1 deletion(-)

diff --git a/arch/arm/mm/proc-v7m.S b/arch/arm/mm/proc-v7m.S
index 59d82864c134b..9c2978c128d97 100644
--- a/arch/arm/mm/proc-v7m.S
+++ b/arch/arm/mm/proc-v7m.S
@@ -135,7 +135,6 @@ __v7m_setup_cont:
 	dsb
 	mov	r6, lr			@ save LR
 	ldr	sp, =init_thread_union + THREAD_START_SP
-	stmia	sp, {r0-r3, r12}
 	cpsie	i
 	svc	#0
 1:	cpsid	i
-- 
2.20.1




  parent reply index

Thread overview: 83+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-08 18:49 [PATCH 4.19 00/79] 4.19.83-stable review Greg Kroah-Hartman
2019-11-08 18:49 ` [PATCH 4.19 01/79] kbuild: add -fcf-protection=none when using retpoline flags Greg Kroah-Hartman
2019-11-08 18:49 ` [PATCH 4.19 02/79] regulator: of: fix suspend-min/max-voltage parsing Greg Kroah-Hartman
2019-11-08 18:49 ` [PATCH 4.19 03/79] ASoC: wm8994: Do not register inapplicable controls for WM1811 Greg Kroah-Hartman
2019-11-08 18:49 ` [PATCH 4.19 04/79] arm64: dts: allwinner: a64: pine64-plus: Add PHY regulator delay Greg Kroah-Hartman
2019-11-08 18:49 ` [PATCH 4.19 05/79] arm64: dts: allwinner: a64: sopine-baseboard: " Greg Kroah-Hartman
2019-11-08 18:49 ` [PATCH 4.19 06/79] arm64: dts: Fix gpio to pinmux mapping Greg Kroah-Hartman
2019-11-08 18:49 ` [PATCH 4.19 07/79] regulator: ti-abb: Fix timeout in ti_abb_wait_txdone/ti_abb_clear_all_txdone Greg Kroah-Hartman
2019-11-08 18:49 ` [PATCH 4.19 08/79] ASoC: rt5682: add NULL handler to set_jack function Greg Kroah-Hartman
2019-11-08 18:49 ` [PATCH 4.19 09/79] regulator: pfuze100-regulator: Variable "val" in pfuze100_regulator_probe() could be uninitialized Greg Kroah-Hartman
2019-11-08 18:49 ` [PATCH 4.19 10/79] ASoC: wm_adsp: Dont generate kcontrols without READ flags Greg Kroah-Hartman
2019-11-08 18:49 ` [PATCH 4.19 11/79] ASoc: rockchip: i2s: Fix RPM imbalance Greg Kroah-Hartman
2019-11-08 18:49 ` [PATCH 4.19 12/79] ARM: dts: logicpd-torpedo-som: Remove twl_keypad Greg Kroah-Hartman
2019-11-08 18:49 ` [PATCH 4.19 13/79] pinctrl: ns2: Fix off by one bugs in ns2_pinmux_enable() Greg Kroah-Hartman
2019-11-08 18:49 ` [PATCH 4.19 14/79] ARM: mm: fix alignment handler faults under memory pressure Greg Kroah-Hartman
2019-11-08 18:49 ` [PATCH 4.19 15/79] scsi: qla2xxx: fix a potential NULL pointer dereference Greg Kroah-Hartman
2019-11-08 18:49 ` [PATCH 4.19 16/79] scsi: scsi_dh_alua: handle RTPG sense code correctly during state transitions Greg Kroah-Hartman
2019-11-08 18:49 ` [PATCH 4.19 17/79] scsi: sni_53c710: fix compilation error Greg Kroah-Hartman
2019-11-08 18:49 ` [PATCH 4.19 18/79] scsi: fix kconfig dependency warning related to 53C700_LE_ON_BE Greg Kroah-Hartman
2019-11-08 18:49 ` [PATCH 4.19 19/79] ARM: dts: imx7s: Correct GPTs ipg clock source Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 20/79] perf c2c: Fix memory leak in build_cl_output() Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 21/79] 8250-men-mcb: fix error checking when get_num_ports returns -ENODEV Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 22/79] perf kmem: Fix memory leak in compact_gfp_flags() Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 23/79] ARM: davinci: dm365: Fix McBSP dma_slave_map entry Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 24/79] drm/amdgpu: fix potential VM faults Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 25/79] scsi: target: core: Do not overwrite CDB byte 1 Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 26/79] tracing: Fix "gfp_t" format for synthetic events Greg Kroah-Hartman
2019-11-08 18:50 ` Greg Kroah-Hartman [this message]
2019-11-08 18:50 ` [PATCH 4.19 28/79] of: unittest: fix memory leak in unittest_data_add Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 29/79] MIPS: bmips: mark exception vectors as char arrays Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 30/79] irqchip/gic-v3-its: Use the exact ITSList for VMOVP Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 31/79] i2c: stm32f7: fix first byte to send in slave mode Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 32/79] i2c: stm32f7: fix a race in slave mode with arbitration loss irq Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 33/79] i2c: stm32f7: remove warning when compiling with W=1 Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 34/79] cifs: Fix cifsInodeInfo lock_sem deadlock when reconnect occurs Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 35/79] nbd: protect cmd->status with cmd->lock Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 36/79] nbd: handle racing with errored out commands Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 37/79] cxgb4: fix panic when attaching to ULD fail Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 38/79] dccp: do not leak jiffies on the wire Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 39/79] erspan: fix the tun_info options_len check for erspan Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 40/79] inet: stop leaking jiffies on the wire Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 41/79] net: annotate accesses to sk->sk_incoming_cpu Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 42/79] net: annotate lockless accesses to sk->sk_napi_id Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 43/79] net: dsa: bcm_sf2: Fix IMP setup for port different than 8 Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 44/79] net: ethernet: ftgmac100: Fix DMA coherency issue with SW checksum Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 45/79] net: fix sk_page_frag() recursion from memory reclaim Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 46/79] net: hisilicon: Fix ping latency when deal with high throughput Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 47/79] net/mlx4_core: Dynamically set guaranteed amount of counters per VF Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 48/79] netns: fix GFP flags in rtnl_net_notifyid() Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 49/79] net: usb: lan78xx: Disable interrupts before calling generic_handle_irq() Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 50/79] net: Zeroing the structure ethtool_wolinfo in ethtool_get_wol() Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 51/79] selftests: net: reuseport_dualstack: fix uninitalized parameter Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 52/79] udp: fix data-race in udp_set_dev_scratch() Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 53/79] vxlan: check tun_info options_len properly Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 54/79] net: add skb_queue_empty_lockless() Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 55/79] udp: use skb_queue_empty_lockless() Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 56/79] net: use skb_queue_empty_lockless() in poll() handlers Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 57/79] net: use skb_queue_empty_lockless() in busy poll contexts Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 58/79] net: add READ_ONCE() annotation in __skb_wait_for_more_packets() Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 59/79] ipv4: fix route update on metric change Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 60/79] selftests: fib_tests: add more tests for metric update Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 61/79] net/mlx5e: Fix handling of compressed CQEs in case of low NAPI budget Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 62/79] r8169: fix wrong PHY ID issue with RTL8168dp Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 63/79] net/mlx5e: Fix ethtool self test: link speed Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 64/79] net: dsa: b53: Do not clear existing mirrored port mask Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 65/79] net: bcmgenet: dont set phydev->link from MAC Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 66/79] net: phy: bcm7xxx: define soft_reset for 40nm EPHY Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 67/79] net: bcmgenet: reset 40nm EPHY on energy detect Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 68/79] net: usb: lan78xx: Connect PHY before registering MAC Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 69/79] net: dsa: fix switch tree list Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 70/79] r8152: add device id for Lenovo ThinkPad USB-C Dock Gen 2 Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 71/79] net/flow_dissector: switch to siphash Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 72/79] wireless: Skip directory when generating certificates Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 73/79] platform/x86: pmc_atom: Add Siemens SIMATIC IPC227E to critclk_systems DMI table Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 74/79] powerpc/mm: Fixup tlbie vs mtpidr/mtlpidr ordering issue on POWER9 Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 75/79] selftests/powerpc: Add test case for tlbie vs mtpidr ordering issue Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 76/79] selftests/powerpc: Fix compile error on tlbie_test due to newer gcc Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 77/79] ASoC: pcm3168a: The codec does not support S32_LE Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 78/79] arm64: dts: ti: k3-am65-main: Fix gic-its node unit-address Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.19 79/79] usb: gadget: udc: core: Fix segfault if udc_bind_to_driver() for pending driver fails Greg Kroah-Hartman
2019-11-08 23:57 ` [PATCH 4.19 00/79] 4.19.83-stable review kernelci.org bot
2019-11-09 10:46 ` Naresh Kamboju
2019-11-09 15:40 ` Guenter Roeck

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