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[PATCH 4.4 02/60] ARM: 8452/3: PJ4: make coprocessor access sequences buildable in Thumb2 mode

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4.4-stable review patch.  If anyone has any objections, please let me know.

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

From: Ard Biesheuvel <ard.biesheuvel@linaro.org>

commit 5008efc83bf85b647aa1cbc44718b1675bbb7444 upstream.

The PJ4 inline asm sequence to write to cp15 cannot be built in Thumb-2
mode, due to the way it performs arithmetic on the program counter, so it
is built in ARM mode instead. However, building C files in ARM mode under
CONFIG_THUMB2_KERNEL is problematic, since the instrumentation performed
by subsystems like ftrace does not expect having to deal with interworking
branches.

Since the sequence in question is simply a poor man's ISB instruction,
let's use a straight 'isb' instead when building in Thumb2 mode. Thumb2
implies V7, so 'isb' should always be supported in that case.

Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/arm/kernel/Makefile  |    1 -
 arch/arm/kernel/pj4-cp0.c |    4 ++++
 2 files changed, 4 insertions(+), 1 deletion(-)

--- a/arch/arm/kernel/Makefile
+++ b/arch/arm/kernel/Makefile
@@ -73,7 +73,6 @@ obj-$(CONFIG_IWMMXT)		+= iwmmxt.o
 obj-$(CONFIG_PERF_EVENTS)	+= perf_regs.o perf_callchain.o
 obj-$(CONFIG_HW_PERF_EVENTS)	+= perf_event_xscale.o perf_event_v6.o \
 				   perf_event_v7.o
-CFLAGS_pj4-cp0.o		:= -marm
 AFLAGS_iwmmxt.o			:= -Wa,-mcpu=iwmmxt
 obj-$(CONFIG_ARM_CPU_TOPOLOGY)  += topology.o
 obj-$(CONFIG_VDSO)		+= vdso.o
--- a/arch/arm/kernel/pj4-cp0.c
+++ b/arch/arm/kernel/pj4-cp0.c
@@ -66,9 +66,13 @@ static void __init pj4_cp_access_write(u
 
 	__asm__ __volatile__ (
 		"mcr	p15, 0, %1, c1, c0, 2\n\t"
+#ifdef CONFIG_THUMB2_KERNEL
+		"isb\n\t"
+#else
 		"mrc	p15, 0, %0, c1, c0, 2\n\t"
 		"mov	%0, %0\n\t"
 		"sub	pc, pc, #4\n\t"
+#endif
 		: "=r" (temp) : "r" (value));
 }
 

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[PATCH 4.4 00/60] 4.4.68-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-11 16:40 +0200
  [PATCH 4.4 10/60] power: supply: bq24190_charger: Handle fault before status on interrupt Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-11 16:40 +0200
  [PATCH 4.4 05/60] power: supply: bq24190_charger: Fix irq trigger to IRQF_TRIGGER_FALLING Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-11 16:40 +0200
  [PATCH 4.4 49/60] tcp: do not underestimate skb->truesize in tcp_trim_head() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-11 16:40 +0200
  [PATCH 4.4 11/60] leds: ktd2692: avoid harmless maybe-uninitialized warning Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-11 16:40 +0200
  [PATCH 4.4 45/60] brcmfmac: Make skb header writable before use Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-11 16:40 +0200
  [PATCH 4.4 25/60] usb: host: ohci-exynos: Decrese node refcount on exynos_ehci_get_phy() error paths Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-11 16:40 +0200
  [PATCH 4.4 41/60] scsi: mac_scsi: Fix MAC_SCSI=m option when SCSI=m Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-11 16:40 +0200
  [PATCH 4.4 38/60] USB: serial: sierra: fix bogus alternate-setting assumption Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-11 16:40 +0200
    Re: [PATCH 4.4 38/60] USB: serial: sierra: fix bogus  alternate-setting assumption Ben Hutchings <ben.hutchings@codethink.co.uk> - 2017-05-12 13:30 +0200
      Re: [PATCH 4.4 38/60] USB: serial: sierra: fix bogus  alternate-setting assumption Johan Hovold <johan@kernel.org> - 2017-05-12 14:20 +0200
        Re: [PATCH 4.4 38/60] USB: serial: sierra: fix bogus  alternate-setting assumption Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-12 15:20 +0200
  [PATCH 4.4 40/60] serial: 8250_omap: Fix probe and remove for PM runtime Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-11 16:40 +0200
  [PATCH 4.4 02/60] ARM: 8452/3: PJ4: make coprocessor access sequences buildable in Thumb2 mode Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-11 16:40 +0200
  [PATCH 4.4 19/60] kprobes/x86: Fix kernel panic when certain exception-handling addresses are probed Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-11 16:40 +0200
  [PATCH 4.4 44/60] brcmfmac: Ensure pointer correctly set if skb data location changes Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-11 16:40 +0200
  [PATCH 4.4 47/60] staging: emxx_udc: remove incorrect __init annotations Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-11 16:40 +0200
  [PATCH 4.4 18/60] clk: Make x86/ conditional on CONFIG_COMMON_CLK Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-11 16:40 +0200
  [PATCH 4.4 13/60] mwifiex: debugfs: Fix (sometimes) off-by-1 SSID print Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-11 16:40 +0200
  [PATCH 4.4 55/60] ipv6: initialize route null entry in addrconf_init() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-11 16:40 +0200
  [PATCH 4.4 08/60] power: supply: bq24190_charger: Call power_supply_changed() for relevant component Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-11 16:40 +0200
  [PATCH 4.4 50/60] bpf, arm64: fix jit branch offset related to ldimm64 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-11 16:40 +0200
  [PATCH 4.4 15/60] mwifiex: Avoid skipping WEP key deletion for AP Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-11 16:50 +0200
  [PATCH 4.4 01/60] 9p: fix a potential acl leak Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-11 16:50 +0200
  [PATCH 4.4 14/60] mwifiex: remove redundant dma padding in AMSDU Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-11 16:50 +0200
  Re: [PATCH 4.4 00/60] 4.4.68-stable review Guenter Roeck <linux@roeck-us.net> - 2017-05-11 23:10 +0200
    Re: [PATCH 4.4 00/60] 4.4.68-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-12 18:00 +0200
  Re: [PATCH 4.4 00/60] 4.4.68-stable review Shuah Khan <shuahkh@osg.samsung.com> - 2017-05-12 17:30 +0200
  Re: [PATCH 4.4 00/60] 4.4.68-stable review Guenter Roeck <linux@roeck-us.net> - 2017-05-12 21:50 +0200

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