[PATCH v4 00/15] ARM: enable IRQ stacks and vmap'ed stacks for UP

[PATCH v4 00/15] ARM: enable IRQ stacks and vmap'ed stacks for UP

[Ard Biesheuvel]

First, enable the use of the TLS register to hold the 'current' pointer
for all configurations that can support it, including non-SMP ones that
target v6k or later CPUs, and multi-platform SMP ones that also support
v6 based UP systems.

The remaining configurations are all strictly UP, which means we can
switch to a global variable to hold the current pointer. By doing this,
we can enable THREAD_INFO_IN_TASK, which moves thread info off the
stack, protecting it from overflows. It also permits us to enable IRQ
stacks and vmap'ed stacks for UP configurations as well.

Supporting v6 cores without SMP extensions in SMP configurations (e.g.,
omap2plus_defconfig or imx_v6_v7_defconfig) makes this a bit tricky, and
this is a feature we may consider dropping entirely in the future. But
for the time being, we can support this mode as well.

The accesses to the global variable holding 'current' are constructed in
a way that ensures that no literal pool accesses (and associated D-cache
misses) are needed unless the access is from a module and module PLTs
are enabled. This means that accessing 'current' is just as costly as
before, as it used to require some arithmetic involving the stack
pointer and a load from the thread_info::task field.

However, accessing thread_info itself now also involves a load, although
it should be noted that all thread_info and current accesses now go via
the same variable, which is therefore expected to be hot in the caches
at all times.

Changes since v3:
- remove some dead code from the RiscPC interrupt handling routines
  before porting them to C, as suggested by Russell;
- add clarifying comments to the module loader patch to explain where
  the group relocations are defined, and how to process them;
- add some RBs and TBs

Changes since v2:
- support THREAD_INFO_IN_TASK and the IRQ stack on v7m as well,
- incorporate a v7m cleanup from Vladimir to enable the above,
- avoid declaring smp_on_up globally,
- fix an oversight in the IOP32x IRQ #0 fix
- add some more acks

Changes since RFC/v1:
- add five preparatory patches that move RiscPC, IOP32x and Footbridge
  to GENERIC_IRQ_MULTI_HANDLER so that even these ancient platforms can
  benefit from the IRQ stacks changes for UP that this series proposes
  (contributed by Arnd)
- fix various issues related to SMP+v6 corner cases that were caught by
  kernelci testing;
- add acks from Nico and Linus (thanks!)

Cc: Russell King <linux@armlinux.org.uk>
Cc: Nicolas Pitre <nico@fluxnic.net>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Kees Cook <keescook@chromium.org>
Cc: Keith Packard <keithpac@amazon.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Vladimir Murzin <vladimir.murzin@arm.com>
Cc: Jesse Taube <mr.bossman075@gmail.com>

Ard Biesheuvel (9):
  ARM: riscpc: drop support for IOMD_IRQREQC/IOMD_IRQREQD IRQ groups
  ARM: entry: preserve thread_info pointer in switch_to
  ARM: module: implement support for PC-relative group relocations
  ARM: assembler: add optimized ldr/str macros to load variables from
    memory
  ARM: percpu: add SMP_ON_UP support
  ARM: use TLS register for 'current' on !SMP as well
  ARM: smp: defer TPIDRURO update for SMP v6 configurations too
  ARM: implement THREAD_INFO_IN_TASK for uniprocessor systems
  ARM: v7m: enable support for IRQ stacks

Arnd Bergmann (5):
  ARM: riscpc: use GENERIC_IRQ_MULTI_HANDLER
  ARM: footbridge: use GENERIC_IRQ_MULTI_HANDLER
  ARM: iop32x: offset IRQ numbers by 1
  ARM: iop32x: use GENERIC_IRQ_MULTI_HANDLER
  ARM: remove old-style irq entry

Vladimir Murzin (1):
  irqchip: nvic: Use GENERIC_IRQ_MULTI_HANDLER

 arch/arm/Kconfig                                    |  22 +--
 arch/arm/include/asm/assembler.h                    | 185 ++++++++++++++++----
 arch/arm/include/asm/current.h                      |  37 ++--
 arch/arm/include/asm/elf.h                          |   3 +
 arch/arm/include/asm/entry-macro-multi.S            |  16 --
 arch/arm/include/asm/hardware/entry-macro-iomd.S    | 131 --------------
 arch/arm/include/asm/insn.h                         |  24 +++
 arch/arm/include/asm/irq.h                          |   1 -
 arch/arm/include/asm/mach/arch.h                    |   2 -
 arch/arm/include/asm/percpu.h                       |  25 ++-
 arch/arm/include/asm/switch_to.h                    |   3 +-
 arch/arm/include/asm/thread_info.h                  |  27 ---
 arch/arm/include/asm/tls.h                          |  13 +-
 arch/arm/include/asm/v7m.h                          |   3 +-
 arch/arm/kernel/asm-offsets.c                       |   3 -
 arch/arm/kernel/entry-armv.S                        |  48 ++---
 arch/arm/kernel/entry-common.S                      |  16 +-
 arch/arm/kernel/entry-header.S                      |  13 +-
 arch/arm/kernel/entry-v7m.S                         |  39 +++--
 arch/arm/kernel/head-common.S                       |   4 +-
 arch/arm/kernel/irq.c                               |  17 --
 arch/arm/kernel/module.c                            |  85 +++++++++
 arch/arm/kernel/process.c                           |   7 +-
 arch/arm/kernel/sleep.S                             |   4 +-
 arch/arm/kernel/smp.c                               |  11 ++
 arch/arm/kernel/traps.c                             |   4 +
 arch/arm/mach-footbridge/common.c                   |  87 +++++++++
 arch/arm/mach-footbridge/include/mach/entry-macro.S | 107 -----------
 arch/arm/mach-iop32x/cp6.c                          |  10 +-
 arch/arm/mach-iop32x/include/mach/entry-macro.S     |  31 ----
 arch/arm/mach-iop32x/include/mach/irqs.h            |   2 +-
 arch/arm/mach-iop32x/iop3xx.h                       |   1 +
 arch/arm/mach-iop32x/irq.c                          |  29 ++-
 arch/arm/mach-iop32x/irqs.h                         |  60 ++++---
 arch/arm/mach-rpc/fiq.S                             |   5 +-
 arch/arm/mach-rpc/include/mach/entry-macro.S        |  13 --
 arch/arm/mach-rpc/irq.c                             |  95 ++++++++++
 arch/arm/mm/Kconfig                                 |   1 +
 drivers/irqchip/Kconfig                             |   1 +
 drivers/irqchip/irq-nvic.c                          |  22 +--
 40 files changed, 667 insertions(+), 540 deletions(-)
 delete mode 100644 arch/arm/include/asm/entry-macro-multi.S
 delete mode 100644 arch/arm/include/asm/hardware/entry-macro-iomd.S
 delete mode 100644 arch/arm/mach-footbridge/include/mach/entry-macro.S
 delete mode 100644 arch/arm/mach-iop32x/include/mach/entry-macro.S
 delete mode 100644 arch/arm/mach-rpc/include/mach/entry-macro.S

-- 
2.30.2


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[PATCH v4 01/15] ARM: riscpc: drop support for IOMD_IRQREQC/IOMD_IRQREQD IRQ groups

[Ard Biesheuvel]

IOMD_IRQREQC nor IOMD_IRQREQD are ever defined, so any conditionally
compiled code that depends on them is dead code, and can be removed.

Suggested-by: Russell King <linux@armlinux.org.uk>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 arch/arm/include/asm/hardware/entry-macro-iomd.S | 47 --------------------
 1 file changed, 47 deletions(-)

diff --git a/arch/arm/include/asm/hardware/entry-macro-iomd.S b/arch/arm/include/asm/hardware/entry-macro-iomd.S
index f7692731e514..81441dfa5282 100644
--- a/arch/arm/include/asm/hardware/entry-macro-iomd.S
+++ b/arch/arm/include/asm/hardware/entry-macro-iomd.S
@@ -24,16 +24,6 @@
 		ldrbeq	\irqstat, [\base, #IOMD_IRQREQA]	@ get low priority
 		addeq	\tmp, \tmp, #256		@ irq_prio_d table size
 		teqeq	\irqstat, #0
-#ifdef IOMD_IRQREQC
-		ldrbeq	\irqstat, [\base, #IOMD_IRQREQC]
-		addeq	\tmp, \tmp, #256		@ irq_prio_l table size
-		teqeq	\irqstat, #0
-#endif
-#ifdef IOMD_IRQREQD
-		ldrbeq	\irqstat, [\base, #IOMD_IRQREQD]
-		addeq	\tmp, \tmp, #256		@ irq_prio_lc table size
-		teqeq	\irqstat, #0
-#endif
 2406:		ldrbne	\irqnr, [\tmp, \irqstat]	@ get IRQ number
 		.endm
 
@@ -92,40 +82,3 @@ irq_prio_l:	.byte	 0, 0, 1, 0, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3
 		.byte	 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7
 		.byte	 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7
 		.byte	 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7
-#ifdef IOMD_IRQREQC
-irq_prio_lc:	.byte	24,24,25,24,26,26,26,26,27,27,27,27,27,27,27,27
-		.byte	28,24,25,24,26,26,26,26,27,27,27,27,27,27,27,27
-		.byte	29,29,29,29,29,29,29,29,29,29,29,29,29,29,29,29
-		.byte	29,29,29,29,29,29,29,29,29,29,29,29,29,29,29,29
-		.byte	30,30,30,30,30,30,30,30,27,27,27,27,27,27,27,27
-		.byte	30,30,30,30,30,30,30,30,27,27,27,27,27,27,27,27
-		.byte	29,29,29,29,29,29,29,29,29,29,29,29,29,29,29,29
-		.byte	29,29,29,29,29,29,29,29,29,29,29,29,29,29,29,29
-		.byte	31,31,31,31,31,31,31,31,31,31,31,31,31,31,31,31
-		.byte	31,31,31,31,31,31,31,31,31,31,31,31,31,31,31,31
-		.byte	31,31,31,31,31,31,31,31,31,31,31,31,31,31,31,31
-		.byte	31,31,31,31,31,31,31,31,31,31,31,31,31,31,31,31
-		.byte	31,31,31,31,31,31,31,31,31,31,31,31,31,31,31,31
-		.byte	31,31,31,31,31,31,31,31,31,31,31,31,31,31,31,31
-		.byte	31,31,31,31,31,31,31,31,31,31,31,31,31,31,31,31
-		.byte	31,31,31,31,31,31,31,31,31,31,31,31,31,31,31,31
-#endif
-#ifdef IOMD_IRQREQD
-irq_prio_ld:	.byte	40,40,41,40,42,42,42,42,43,43,43,43,43,43,43,43
-		.byte	44,40,41,40,42,42,42,42,43,43,43,43,43,43,43,43
-		.byte	45,45,45,45,45,45,45,45,45,45,45,45,45,45,45,45
-		.byte	45,45,45,45,45,45,45,45,45,45,45,45,45,45,45,45
-		.byte	46,46,46,46,46,46,46,46,43,43,43,43,43,43,43,43
-		.byte	46,46,46,46,46,46,46,46,43,43,43,43,43,43,43,43
-		.byte	45,45,45,45,45,45,45,45,45,45,45,45,45,45,45,45
-		.byte	45,45,45,45,45,45,45,45,45,45,45,45,45,45,45,45
-		.byte	47,47,47,47,47,47,47,47,47,47,47,47,47,47,47,47
-		.byte	47,47,47,47,47,47,47,47,47,47,47,47,47,47,47,47
-		.byte	47,47,47,47,47,47,47,47,47,47,47,47,47,47,47,47
-		.byte	47,47,47,47,47,47,47,47,47,47,47,47,47,47,47,47
-		.byte	47,47,47,47,47,47,47,47,47,47,47,47,47,47,47,47
-		.byte	47,47,47,47,47,47,47,47,47,47,47,47,47,47,47,47
-		.byte	47,47,47,47,47,47,47,47,47,47,47,47,47,47,47,47
-		.byte	47,47,47,47,47,47,47,47,47,47,47,47,47,47,47,47
-#endif
-
-- 
2.30.2


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[PATCH v4 02/15] ARM: riscpc: use GENERIC_IRQ_MULTI_HANDLER

[Ard Biesheuvel]

From: Arnd Bergmann <arnd@arndb.de>

This is one of the last platforms using the old entry path.
While this code path is spread over a few files, it is fairly
straightforward to convert it into an equivalent C version,
leaving the existing algorithm and all the priority handling
the same.

Unlike most irqchip drivers, this means reading the status
register(s) in a loop and always handling the highest-priority
irq first.

The IOMD_IRQREQC and IOMD_IRQREQD registers are not actaully
used here, but I left the code in place for the time being,
to keep the conversion as direct as possible. It could be
removed in a cleanup on top.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
[ardb: drop obsolete IOMD_IRQREQC/IOMD_IRQREQD handling]
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Marc Zyngier <maz@kernel.org>
Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M
---
 arch/arm/Kconfig                                 |  1 +
 arch/arm/include/asm/hardware/entry-macro-iomd.S | 84 -----------------
 arch/arm/mach-rpc/fiq.S                          |  5 +-
 arch/arm/mach-rpc/include/mach/entry-macro.S     | 13 ---
 arch/arm/mach-rpc/irq.c                          | 95 ++++++++++++++++++++
 5 files changed, 99 insertions(+), 99 deletions(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index e2ab72f2bf4a..25f1868e5703 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -444,6 +444,7 @@ config ARCH_RPC
 	select ARM_HAS_SG_CHAIN
 	select CPU_SA110
 	select FIQ
+	select GENERIC_IRQ_MULTI_HANDLER
 	select HAVE_PATA_PLATFORM
 	select ISA_DMA_API
 	select LEGACY_TIMER_TICK
diff --git a/arch/arm/include/asm/hardware/entry-macro-iomd.S b/arch/arm/include/asm/hardware/entry-macro-iomd.S
deleted file mode 100644
index 81441dfa5282..000000000000
--- a/arch/arm/include/asm/hardware/entry-macro-iomd.S
+++ /dev/null
@@ -1,84 +0,0 @@
-/*
- * arch/arm/include/asm/hardware/entry-macro-iomd.S
- *
- * Low-level IRQ helper macros for IOC/IOMD based platforms
- *
- * This file is licensed under  the terms of the GNU General Public
- * License version 2. This program is licensed "as is" without any
- * warranty of any kind, whether express or implied.
- */
-
-/* IOC / IOMD based hardware */
-#include <asm/hardware/iomd.h>
-
-		.macro	get_irqnr_and_base, irqnr, irqstat, base, tmp
-		ldrb	\irqstat, [\base, #IOMD_IRQREQB]	@ get high priority first
-		ldr	\tmp, =irq_prio_h
-		teq	\irqstat, #0
-#ifdef IOMD_BASE
-		ldrbeq	\irqstat, [\base, #IOMD_DMAREQ]	@ get dma
-		addeq	\tmp, \tmp, #256		@ irq_prio_h table size
-		teqeq	\irqstat, #0
-		bne	2406f
-#endif
-		ldrbeq	\irqstat, [\base, #IOMD_IRQREQA]	@ get low priority
-		addeq	\tmp, \tmp, #256		@ irq_prio_d table size
-		teqeq	\irqstat, #0
-2406:		ldrbne	\irqnr, [\tmp, \irqstat]	@ get IRQ number
-		.endm
-
-/*
- * Interrupt table (incorporates priority).  Please note that we
- * rely on the order of these tables (see above code).
- */
-		.align	5
-irq_prio_h:	.byte	 0, 8, 9, 8,10,10,10,10,11,11,11,11,10,10,10,10
-		.byte	12, 8, 9, 8,10,10,10,10,11,11,11,11,10,10,10,10
-		.byte	13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10
-		.byte	13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10
-		.byte	14,14,14,14,10,10,10,10,11,11,11,11,10,10,10,10
-		.byte	14,14,14,14,10,10,10,10,11,11,11,11,10,10,10,10
-		.byte	13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10
-		.byte	13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10
-		.byte	15,15,15,15,10,10,10,10,11,11,11,11,10,10,10,10
-		.byte	15,15,15,15,10,10,10,10,11,11,11,11,10,10,10,10
-		.byte	13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10
-		.byte	13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10
-		.byte	15,15,15,15,10,10,10,10,11,11,11,11,10,10,10,10
-		.byte	15,15,15,15,10,10,10,10,11,11,11,11,10,10,10,10
-		.byte	13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10
-		.byte	13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10
-#ifdef IOMD_BASE
-irq_prio_d:	.byte	 0,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16
-		.byte	20,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16
-		.byte	21,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16
-		.byte	21,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16
-		.byte	22,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16
-		.byte	22,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16
-		.byte	21,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16
-		.byte	21,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16
-		.byte	23,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16
-		.byte	23,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16
-		.byte	21,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16
-		.byte	21,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16
-		.byte	22,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16
-		.byte	22,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16
-		.byte	21,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16
-		.byte	21,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16
-#endif
-irq_prio_l:	.byte	 0, 0, 1, 0, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3
-		.byte	 4, 0, 1, 0, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3
-		.byte	 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5
-		.byte	 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5
-		.byte	 6, 6, 6, 6, 6, 6, 6, 6, 3, 3, 3, 3, 3, 3, 3, 3
-		.byte	 6, 6, 6, 6, 6, 6, 6, 6, 3, 3, 3, 3, 3, 3, 3, 3
-		.byte	 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5
-		.byte	 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5
-		.byte	 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7
-		.byte	 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7
-		.byte	 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7
-		.byte	 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7
-		.byte	 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7
-		.byte	 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7
-		.byte	 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7
-		.byte	 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7
diff --git a/arch/arm/mach-rpc/fiq.S b/arch/arm/mach-rpc/fiq.S
index 0de83e9b0b39..087bdf4bc093 100644
--- a/arch/arm/mach-rpc/fiq.S
+++ b/arch/arm/mach-rpc/fiq.S
@@ -2,10 +2,11 @@
 #include <linux/linkage.h>
 #include <asm/assembler.h>
 #include <mach/hardware.h>
-#include <mach/entry-macro.S>
 
-	.text
+	.equ	ioc_base_high, IOC_BASE & 0xff000000
+	.equ	ioc_base_low, IOC_BASE & 0x00ff0000
 
+	.text
 	.global	rpc_default_fiq_end
 ENTRY(rpc_default_fiq_start)
 	mov	r12, #ioc_base_high
diff --git a/arch/arm/mach-rpc/include/mach/entry-macro.S b/arch/arm/mach-rpc/include/mach/entry-macro.S
deleted file mode 100644
index a6d1a9f4bb79..000000000000
--- a/arch/arm/mach-rpc/include/mach/entry-macro.S
+++ /dev/null
@@ -1,13 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-#include <mach/hardware.h>
-#include <asm/hardware/entry-macro-iomd.S>
-
-	.equ	ioc_base_high, IOC_BASE & 0xff000000
-	.equ	ioc_base_low, IOC_BASE & 0x00ff0000
-
-	.macro  get_irqnr_preamble, base, tmp
-	mov	\base, #ioc_base_high		@ point at IOC
-	.if	ioc_base_low
-	orr	\base, \base, #ioc_base_low
-	.endif
-	.endm
diff --git a/arch/arm/mach-rpc/irq.c b/arch/arm/mach-rpc/irq.c
index 803aeb126f0e..dc29384b6ef8 100644
--- a/arch/arm/mach-rpc/irq.c
+++ b/arch/arm/mach-rpc/irq.c
@@ -14,6 +14,99 @@
 #define CLR	0x04
 #define MASK	0x08
 
+static const u8 irq_prio_h[256] = {
+	 0, 8, 9, 8,10,10,10,10,11,11,11,11,10,10,10,10,
+	12, 8, 9, 8,10,10,10,10,11,11,11,11,10,10,10,10,
+	13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10,
+	13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10,
+	14,14,14,14,10,10,10,10,11,11,11,11,10,10,10,10,
+	14,14,14,14,10,10,10,10,11,11,11,11,10,10,10,10,
+	13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10,
+	13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10,
+	15,15,15,15,10,10,10,10,11,11,11,11,10,10,10,10,
+	15,15,15,15,10,10,10,10,11,11,11,11,10,10,10,10,
+	13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10,
+	13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10,
+	15,15,15,15,10,10,10,10,11,11,11,11,10,10,10,10,
+	15,15,15,15,10,10,10,10,11,11,11,11,10,10,10,10,
+	13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10,
+	13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10,
+};
+
+static const u8 irq_prio_d[256] = {
+	 0,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
+	20,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
+	21,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
+	21,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
+	22,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
+	22,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
+	21,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
+	21,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
+	23,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
+	23,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
+	21,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
+	21,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
+	22,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
+	22,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
+	21,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
+	21,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
+};
+
+static const u8 irq_prio_l[256] = {
+	 0, 0, 1, 0, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3,
+	 4, 0, 1, 0, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3,
+	 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
+	 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
+	 6, 6, 6, 6, 6, 6, 6, 6, 3, 3, 3, 3, 3, 3, 3, 3,
+	 6, 6, 6, 6, 6, 6, 6, 6, 3, 3, 3, 3, 3, 3, 3, 3,
+	 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
+	 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
+	 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
+	 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
+	 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
+	 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
+	 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
+	 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
+	 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
+	 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
+};
+
+static int iomd_get_irq_nr(void)
+{
+	int irq;
+	u8 reg;
+
+	/* get highest priority first */
+	reg = readb(IOC_BASE + IOMD_IRQREQB);
+	irq = irq_prio_h[reg];
+	if (irq)
+		return irq;
+
+	/* get DMA  */
+	reg = readb(IOC_BASE + IOMD_DMAREQ);
+	irq = irq_prio_d[reg];
+	if (irq)
+		return irq;
+
+	/* get low priority */
+	reg = readb(IOC_BASE + IOMD_IRQREQA);
+	irq = irq_prio_l[reg];
+	if (irq)
+		return irq;
+	return 0;
+}
+
+static void iomd_handle_irq(struct pt_regs *regs)
+{
+	int irq;
+
+	do {
+		irq = iomd_get_irq_nr();
+		if (irq)
+			generic_handle_irq(irq);
+	} while (irq);
+}
+
 static void __iomem *iomd_get_base(struct irq_data *d)
 {
 	void *cd = irq_data_get_irq_chip_data(d);
@@ -82,6 +175,8 @@ void __init rpc_init_irq(void)
 	set_fiq_handler(&rpc_default_fiq_start,
 		&rpc_default_fiq_end - &rpc_default_fiq_start);
 
+	set_handle_irq(iomd_handle_irq);
+
 	for (irq = 0; irq < NR_IRQS; irq++) {
 		clr = IRQ_NOREQUEST;
 		set = 0;
-- 
2.30.2


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[PATCH v4 03/15] ARM: footbridge: use GENERIC_IRQ_MULTI_HANDLER

[Ard Biesheuvel]

From: Arnd Bergmann <arnd@arndb.de>

Footbridge still uses the classic IRQ entry path in assembler,
but this is easily converted into an equivalent C version.

In this case, the correlation between IRQ numbers and bits in
the status register is non-obvious, and the priorities are
handled by manually checking each bit in a static order,
re-reading the status register after each handled event.

I moved the code into the new file and edited the syntax without
changing this sequence to keep the behavior as close as possible
to what it traditionally did.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Marc Zyngier <maz@kernel.org>
Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
---
 arch/arm/Kconfig                                    |   1 +
 arch/arm/mach-footbridge/common.c                   |  87 ++++++++++++++++
 arch/arm/mach-footbridge/include/mach/entry-macro.S | 107 --------------------
 3 files changed, 88 insertions(+), 107 deletions(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 25f1868e5703..a0cc9ca66ae0 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -362,6 +362,7 @@ config ARCH_FOOTBRIDGE
 	select FOOTBRIDGE
 	select NEED_MACH_IO_H if !MMU
 	select NEED_MACH_MEMORY_H
+	select GENERIC_IRQ_MULTI_HANDLER
 	help
 	  Support for systems based on the DC21285 companion chip
 	  ("FootBridge"), such as the Simtec CATS and the Rebel NetWinder.
diff --git a/arch/arm/mach-footbridge/common.c b/arch/arm/mach-footbridge/common.c
index eee095f0e2f6..322495df271d 100644
--- a/arch/arm/mach-footbridge/common.c
+++ b/arch/arm/mach-footbridge/common.c
@@ -27,6 +27,91 @@
 
 #include "common.h"
 
+#include <mach/hardware.h>
+#include <mach/irqs.h>
+#include <asm/hardware/dec21285.h>
+
+static int dc21285_get_irq(void)
+{
+	void __iomem *irqstatus = (void __iomem *)CSR_IRQ_STATUS;
+	u32 mask = readl(irqstatus);
+
+	if (mask & IRQ_MASK_SDRAMPARITY)
+		return IRQ_SDRAMPARITY;
+
+	if (mask & IRQ_MASK_UART_RX)
+		return IRQ_CONRX;
+
+	if (mask & IRQ_MASK_DMA1)
+		return IRQ_DMA1;
+
+	if (mask & IRQ_MASK_DMA2)
+		return IRQ_DMA2;
+
+	if (mask & IRQ_MASK_IN0)
+		return IRQ_IN0;
+
+	if (mask & IRQ_MASK_IN1)
+		return IRQ_IN1;
+
+	if (mask & IRQ_MASK_IN2)
+		return IRQ_IN2;
+
+	if (mask & IRQ_MASK_IN3)
+		return IRQ_IN3;
+
+	if (mask & IRQ_MASK_PCI)
+		return IRQ_PCI;
+
+	if (mask & IRQ_MASK_DOORBELLHOST)
+		return IRQ_DOORBELLHOST;
+
+	if (mask & IRQ_MASK_I2OINPOST)
+		return IRQ_I2OINPOST;
+
+	if (mask & IRQ_MASK_TIMER1)
+		return IRQ_TIMER1;
+
+	if (mask & IRQ_MASK_TIMER2)
+		return IRQ_TIMER2;
+
+	if (mask & IRQ_MASK_TIMER3)
+		return IRQ_TIMER3;
+
+	if (mask & IRQ_MASK_UART_TX)
+		return IRQ_CONTX;
+
+	if (mask & IRQ_MASK_PCI_ABORT)
+		return IRQ_PCI_ABORT;
+
+	if (mask & IRQ_MASK_PCI_SERR)
+		return IRQ_PCI_SERR;
+
+	if (mask & IRQ_MASK_DISCARD_TIMER)
+		return IRQ_DISCARD_TIMER;
+
+	if (mask & IRQ_MASK_PCI_DPERR)
+		return IRQ_PCI_DPERR;
+
+	if (mask & IRQ_MASK_PCI_PERR)
+		return IRQ_PCI_PERR;
+
+	return 0;
+}
+
+static void dc21285_handle_irq(struct pt_regs *regs)
+{
+	int irq;
+	do {
+		irq = dc21285_get_irq();
+		if (!irq)
+			break;
+
+		generic_handle_irq(irq);
+	} while (1);
+}
+
+
 unsigned int mem_fclk_21285 = 50000000;
 
 EXPORT_SYMBOL(mem_fclk_21285);
@@ -108,6 +193,8 @@ static void __init __fb_init_irq(void)
 
 void __init footbridge_init_irq(void)
 {
+	set_handle_irq(dc21285_handle_irq);
+
 	__fb_init_irq();
 
 	if (!footbridge_cfn_mode())
diff --git a/arch/arm/mach-footbridge/include/mach/entry-macro.S b/arch/arm/mach-footbridge/include/mach/entry-macro.S
deleted file mode 100644
index dabbd5c54a78..000000000000
--- a/arch/arm/mach-footbridge/include/mach/entry-macro.S
+++ /dev/null
@@ -1,107 +0,0 @@
-/*
- * arch/arm/mach-footbridge/include/mach/entry-macro.S
- *
- * Low-level IRQ helper macros for footbridge-based platforms
- *
- * This file is licensed under  the terms of the GNU General Public
- * License version 2. This program is licensed "as is" without any
- * warranty of any kind, whether express or implied.
- */
-#include <mach/hardware.h>
-#include <mach/irqs.h>
-#include <asm/hardware/dec21285.h>
-
-		.equ	dc21285_high, ARMCSR_BASE & 0xff000000
-		.equ	dc21285_low, ARMCSR_BASE & 0x00ffffff
-
-		.macro  get_irqnr_preamble, base, tmp
-		mov	\base, #dc21285_high
-		.if	dc21285_low
-		orr	\base, \base, #dc21285_low
-		.endif
-		.endm
-
-		.macro	get_irqnr_and_base, irqnr, irqstat, base, tmp
-		ldr	\irqstat, [\base, #0x180]	@ get interrupts
-
-		mov	\irqnr, #IRQ_SDRAMPARITY
-		tst	\irqstat, #IRQ_MASK_SDRAMPARITY
-		bne	1001f
-
-		tst	\irqstat, #IRQ_MASK_UART_RX
-		movne	\irqnr, #IRQ_CONRX
-		bne	1001f
-
-		tst	\irqstat, #IRQ_MASK_DMA1
-		movne	\irqnr, #IRQ_DMA1
-		bne	1001f
-
-		tst	\irqstat, #IRQ_MASK_DMA2
-		movne	\irqnr, #IRQ_DMA2
-		bne	1001f
-
-		tst	\irqstat, #IRQ_MASK_IN0
-		movne	\irqnr, #IRQ_IN0
-		bne	1001f
-
-		tst	\irqstat, #IRQ_MASK_IN1
-		movne	\irqnr, #IRQ_IN1
-		bne	1001f
-
-		tst	\irqstat, #IRQ_MASK_IN2
-		movne	\irqnr, #IRQ_IN2
-		bne	1001f
-
-		tst	\irqstat, #IRQ_MASK_IN3
-		movne	\irqnr, #IRQ_IN3
-		bne	1001f
-
-		tst	\irqstat, #IRQ_MASK_PCI
-		movne	\irqnr, #IRQ_PCI
-		bne	1001f
-
-		tst	\irqstat, #IRQ_MASK_DOORBELLHOST
-		movne	\irqnr, #IRQ_DOORBELLHOST
-		bne     1001f
-
-		tst	\irqstat, #IRQ_MASK_I2OINPOST
-		movne	\irqnr, #IRQ_I2OINPOST
-		bne	1001f
-
-		tst	\irqstat, #IRQ_MASK_TIMER1
-		movne	\irqnr, #IRQ_TIMER1
-		bne	1001f
-
-		tst	\irqstat, #IRQ_MASK_TIMER2
-		movne	\irqnr, #IRQ_TIMER2
-		bne	1001f
-
-		tst	\irqstat, #IRQ_MASK_TIMER3
-		movne	\irqnr, #IRQ_TIMER3
-		bne	1001f
-
-		tst	\irqstat, #IRQ_MASK_UART_TX
-		movne	\irqnr, #IRQ_CONTX
-		bne	1001f
-
-		tst	\irqstat, #IRQ_MASK_PCI_ABORT
-		movne	\irqnr, #IRQ_PCI_ABORT
-		bne	1001f
-
-		tst	\irqstat, #IRQ_MASK_PCI_SERR
-		movne	\irqnr, #IRQ_PCI_SERR
-		bne	1001f
-
-		tst	\irqstat, #IRQ_MASK_DISCARD_TIMER
-		movne	\irqnr, #IRQ_DISCARD_TIMER
-		bne	1001f
-
-		tst	\irqstat, #IRQ_MASK_PCI_DPERR
-		movne	\irqnr, #IRQ_PCI_DPERR
-		bne	1001f
-
-		tst	\irqstat, #IRQ_MASK_PCI_PERR
-		movne	\irqnr, #IRQ_PCI_PERR
-1001:
-		.endm
-
-- 
2.30.2


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[PATCH v4 04/15] ARM: iop32x: offset IRQ numbers by 1

[Ard Biesheuvel]

From: Arnd Bergmann <arnd@arndb.de>

iop32x is one of the last platforms to use IRQ 0, and this has apparently
stopped working in a 2014 cleanup without anyone noticing. This interrupt
is used for the DMA engine, so most likely this has not actually worked
in the past 7 years, but it's also not essential for using this board.

I'm splitting out this change from my GENERIC_IRQ_MULTI_HANDLER
conversion so it can be backported if anyone cares.

Fixes: a71b092a9c68 ("ARM: Convert handle_IRQ to use __handle_domain_irq")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
[ardb: take +1 offset into account in mask/unmask and init as well]
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Marc Zyngier <maz@kernel.org>
Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
---
 arch/arm/mach-iop32x/include/mach/entry-macro.S |  2 +-
 arch/arm/mach-iop32x/include/mach/irqs.h        |  2 +-
 arch/arm/mach-iop32x/irq.c                      |  6 +-
 arch/arm/mach-iop32x/irqs.h                     | 60 +++++++++++---------
 4 files changed, 37 insertions(+), 33 deletions(-)

diff --git a/arch/arm/mach-iop32x/include/mach/entry-macro.S b/arch/arm/mach-iop32x/include/mach/entry-macro.S
index 8e6766d4621e..341e5d9a6616 100644
--- a/arch/arm/mach-iop32x/include/mach/entry-macro.S
+++ b/arch/arm/mach-iop32x/include/mach/entry-macro.S
@@ -20,7 +20,7 @@
 	mrc     p6, 0, \irqstat, c8, c0, 0	@ Read IINTSRC
 	cmp     \irqstat, #0
 	clzne   \irqnr, \irqstat
-	rsbne   \irqnr, \irqnr, #31
+	rsbne   \irqnr, \irqnr, #32
 	.endm
 
 	.macro arch_ret_to_user, tmp1, tmp2
diff --git a/arch/arm/mach-iop32x/include/mach/irqs.h b/arch/arm/mach-iop32x/include/mach/irqs.h
index c4e78df428e8..e09ae5f48aec 100644
--- a/arch/arm/mach-iop32x/include/mach/irqs.h
+++ b/arch/arm/mach-iop32x/include/mach/irqs.h
@@ -9,6 +9,6 @@
 #ifndef __IRQS_H
 #define __IRQS_H
 
-#define NR_IRQS			32
+#define NR_IRQS			33
 
 #endif
diff --git a/arch/arm/mach-iop32x/irq.c b/arch/arm/mach-iop32x/irq.c
index 2d48bf1398c1..d1e8824cbd82 100644
--- a/arch/arm/mach-iop32x/irq.c
+++ b/arch/arm/mach-iop32x/irq.c
@@ -32,14 +32,14 @@ static void intstr_write(u32 val)
 static void
 iop32x_irq_mask(struct irq_data *d)
 {
-	iop32x_mask &= ~(1 << d->irq);
+	iop32x_mask &= ~(1 << (d->irq - 1));
 	intctl_write(iop32x_mask);
 }
 
 static void
 iop32x_irq_unmask(struct irq_data *d)
 {
-	iop32x_mask |= 1 << d->irq;
+	iop32x_mask |= 1 << (d->irq - 1);
 	intctl_write(iop32x_mask);
 }
 
@@ -65,7 +65,7 @@ void __init iop32x_init_irq(void)
 	    machine_is_em7210())
 		*IOP3XX_PCIIRSR = 0x0f;
 
-	for (i = 0; i < NR_IRQS; i++) {
+	for (i = 1; i < NR_IRQS; i++) {
 		irq_set_chip_and_handler(i, &ext_chip, handle_level_irq);
 		irq_clear_status_flags(i, IRQ_NOREQUEST | IRQ_NOPROBE);
 	}
diff --git a/arch/arm/mach-iop32x/irqs.h b/arch/arm/mach-iop32x/irqs.h
index 69858e4e905d..e1dfc8b4e7d7 100644
--- a/arch/arm/mach-iop32x/irqs.h
+++ b/arch/arm/mach-iop32x/irqs.h
@@ -7,36 +7,40 @@
 #ifndef __IOP32X_IRQS_H
 #define __IOP32X_IRQS_H
 
+/* Interrupts in Linux start at 1, hardware starts at 0 */
+
+#define IOP_IRQ(x) ((x) + 1)
+
 /*
  * IOP80321 chipset interrupts
  */
-#define IRQ_IOP32X_DMA0_EOT	0
-#define IRQ_IOP32X_DMA0_EOC	1
-#define IRQ_IOP32X_DMA1_EOT	2
-#define IRQ_IOP32X_DMA1_EOC	3
-#define IRQ_IOP32X_AA_EOT	6
-#define IRQ_IOP32X_AA_EOC	7
-#define IRQ_IOP32X_CORE_PMON	8
-#define IRQ_IOP32X_TIMER0	9
-#define IRQ_IOP32X_TIMER1	10
-#define IRQ_IOP32X_I2C_0	11
-#define IRQ_IOP32X_I2C_1	12
-#define IRQ_IOP32X_MESSAGING	13
-#define IRQ_IOP32X_ATU_BIST	14
-#define IRQ_IOP32X_PERFMON	15
-#define IRQ_IOP32X_CORE_PMU	16
-#define IRQ_IOP32X_BIU_ERR	17
-#define IRQ_IOP32X_ATU_ERR	18
-#define IRQ_IOP32X_MCU_ERR	19
-#define IRQ_IOP32X_DMA0_ERR	20
-#define IRQ_IOP32X_DMA1_ERR	21
-#define IRQ_IOP32X_AA_ERR	23
-#define IRQ_IOP32X_MSG_ERR	24
-#define IRQ_IOP32X_SSP		25
-#define IRQ_IOP32X_XINT0	27
-#define IRQ_IOP32X_XINT1	28
-#define IRQ_IOP32X_XINT2	29
-#define IRQ_IOP32X_XINT3	30
-#define IRQ_IOP32X_HPI		31
+#define IRQ_IOP32X_DMA0_EOT	IOP_IRQ(0)
+#define IRQ_IOP32X_DMA0_EOC	IOP_IRQ(1)
+#define IRQ_IOP32X_DMA1_EOT	IOP_IRQ(2)
+#define IRQ_IOP32X_DMA1_EOC	IOP_IRQ(3)
+#define IRQ_IOP32X_AA_EOT	IOP_IRQ(6)
+#define IRQ_IOP32X_AA_EOC	IOP_IRQ(7)
+#define IRQ_IOP32X_CORE_PMON	IOP_IRQ(8)
+#define IRQ_IOP32X_TIMER0	IOP_IRQ(9)
+#define IRQ_IOP32X_TIMER1	IOP_IRQ(10)
+#define IRQ_IOP32X_I2C_0	IOP_IRQ(11)
+#define IRQ_IOP32X_I2C_1	IOP_IRQ(12)
+#define IRQ_IOP32X_MESSAGING	IOP_IRQ(13)
+#define IRQ_IOP32X_ATU_BIST	IOP_IRQ(14)
+#define IRQ_IOP32X_PERFMON	IOP_IRQ(15)
+#define IRQ_IOP32X_CORE_PMU	IOP_IRQ(16)
+#define IRQ_IOP32X_BIU_ERR	IOP_IRQ(17)
+#define IRQ_IOP32X_ATU_ERR	IOP_IRQ(18)
+#define IRQ_IOP32X_MCU_ERR	IOP_IRQ(19)
+#define IRQ_IOP32X_DMA0_ERR	IOP_IRQ(20)
+#define IRQ_IOP32X_DMA1_ERR	IOP_IRQ(21)
+#define IRQ_IOP32X_AA_ERR	IOP_IRQ(23)
+#define IRQ_IOP32X_MSG_ERR	IOP_IRQ(24)
+#define IRQ_IOP32X_SSP		IOP_IRQ(25)
+#define IRQ_IOP32X_XINT0	IOP_IRQ(27)
+#define IRQ_IOP32X_XINT1	IOP_IRQ(28)
+#define IRQ_IOP32X_XINT2	IOP_IRQ(29)
+#define IRQ_IOP32X_XINT3	IOP_IRQ(30)
+#define IRQ_IOP32X_HPI		IOP_IRQ(31)
 
 #endif
-- 
2.30.2


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[PATCH v4 05/15] ARM: iop32x: use GENERIC_IRQ_MULTI_HANDLER

[Ard Biesheuvel]

From: Arnd Bergmann <arnd@arndb.de>

iop32x uses the entry-macro.S file for both the IRQ entry and for
hooking into the arch_ret_to_user code path. This is done because the
cp6 registers have to be enabled before accessing any of the interrupt
controller registers but have to be disabled when running in user space.

There is also a lazy-enable logic in cp6.c, but during a hardirq, we
know it has to be enabled.

Both the cp6-enable code and the code to read the IRQ status can be
lifted into the normal generic_handle_arch_irq() path, but the
cp6-disable code has to remain in the user return code. As nothing
other than iop32x uses this hook, just open-code it there with an
ifdef for the platform that can eventually be removed when iop32x
has reached the end of its life.

The cp6-enable path in the IRQ entry has an extra cp_wait barrier that
the trap version does not have, but it is harmless to do it in both
cases to simplify the logic here at the cost of a few extra cycles
for the trap.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Marc Zyngier <maz@kernel.org>
Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M
---
 arch/arm/Kconfig                                |  5 +---
 arch/arm/kernel/entry-common.S                  | 16 +++++-----
 arch/arm/mach-iop32x/cp6.c                      | 10 ++++++-
 arch/arm/mach-iop32x/include/mach/entry-macro.S | 31 --------------------
 arch/arm/mach-iop32x/iop3xx.h                   |  1 +
 arch/arm/mach-iop32x/irq.c                      | 23 +++++++++++++++
 6 files changed, 43 insertions(+), 43 deletions(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index a0cc9ca66ae0..d9ba6961b295 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -227,9 +227,6 @@ config GENERIC_ISA_DMA
 config FIQ
 	bool
 
-config NEED_RET_TO_USER
-	bool
-
 config ARCH_MTD_XIP
 	bool
 
@@ -371,9 +368,9 @@ config ARCH_IOP32X
 	bool "IOP32x-based"
 	depends on MMU
 	select CPU_XSCALE
+	select GENERIC_IRQ_MULTI_HANDLER
 	select GPIO_IOP
 	select GPIOLIB
-	select NEED_RET_TO_USER
 	select FORCE_PCI
 	select PLAT_IOP
 	help
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index ac86c34682bb..c928d6b04cce 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -16,12 +16,14 @@
 
 	.equ	NR_syscalls, __NR_syscalls
 
-#ifdef CONFIG_NEED_RET_TO_USER
-#include <mach/entry-macro.S>
-#else
-	.macro  arch_ret_to_user, tmp1, tmp2
-	.endm
+	.macro  arch_ret_to_user, tmp
+#ifdef CONFIG_ARCH_IOP32X
+	mrc	p15, 0, \tmp, c15, c1, 0
+	tst	\tmp, #(1 << 6)
+	bicne	\tmp, \tmp, #(1 << 6)
+	mcrne	p15, 0, \tmp, c15, c1, 0	@ Disable cp6 access
 #endif
+	.endm
 
 #include "entry-header.S"
 
@@ -55,7 +57,7 @@ __ret_fast_syscall:
 
 
 	/* perform architecture specific actions before user return */
-	arch_ret_to_user r1, lr
+	arch_ret_to_user r1
 
 	restore_user_regs fast = 1, offset = S_OFF
  UNWIND(.fnend		)
@@ -128,7 +130,7 @@ no_work_pending:
 	asm_trace_hardirqs_on save = 0
 
 	/* perform architecture specific actions before user return */
-	arch_ret_to_user r1, lr
+	arch_ret_to_user r1
 	ct_user_enter save = 0
 
 	restore_user_regs fast = 0, offset = 0
diff --git a/arch/arm/mach-iop32x/cp6.c b/arch/arm/mach-iop32x/cp6.c
index ec74b07fb7e3..2882674a1c39 100644
--- a/arch/arm/mach-iop32x/cp6.c
+++ b/arch/arm/mach-iop32x/cp6.c
@@ -7,7 +7,7 @@
 #include <asm/traps.h>
 #include <asm/ptrace.h>
 
-static int cp6_trap(struct pt_regs *regs, unsigned int instr)
+void iop_enable_cp6(void)
 {
 	u32 temp;
 
@@ -16,7 +16,15 @@ static int cp6_trap(struct pt_regs *regs, unsigned int instr)
 		"mrc	p15, 0, %0, c15, c1, 0\n\t"
 		"orr	%0, %0, #(1 << 6)\n\t"
 		"mcr	p15, 0, %0, c15, c1, 0\n\t"
+		"mrc	p15, 0, %0, c15, c1, 0\n\t"
+		"mov	%0, %0\n\t"
+		"sub	pc, pc, #4  @ cp_wait\n\t"
 		: "=r"(temp));
+}
+
+static int cp6_trap(struct pt_regs *regs, unsigned int instr)
+{
+	iop_enable_cp6();
 
 	return 0;
 }
diff --git a/arch/arm/mach-iop32x/include/mach/entry-macro.S b/arch/arm/mach-iop32x/include/mach/entry-macro.S
deleted file mode 100644
index 341e5d9a6616..000000000000
--- a/arch/arm/mach-iop32x/include/mach/entry-macro.S
+++ /dev/null
@@ -1,31 +0,0 @@
-/*
- * arch/arm/mach-iop32x/include/mach/entry-macro.S
- *
- * Low-level IRQ helper macros for IOP32x-based platforms
- *
- * This file is licensed under the terms of the GNU General Public
- * License version 2. This program is licensed "as is" without any
- * warranty of any kind, whether express or implied.
- */
-	.macro get_irqnr_preamble, base, tmp
-	mrc	p15, 0, \tmp, c15, c1, 0
-	orr	\tmp, \tmp, #(1 << 6)
-	mcr	p15, 0, \tmp, c15, c1, 0	@ Enable cp6 access
-	mrc	p15, 0, \tmp, c15, c1, 0
-	mov	\tmp, \tmp
-	sub	pc, pc, #4			@ cp_wait
-	.endm
-
-	.macro  get_irqnr_and_base, irqnr, irqstat, base, tmp
-	mrc     p6, 0, \irqstat, c8, c0, 0	@ Read IINTSRC
-	cmp     \irqstat, #0
-	clzne   \irqnr, \irqstat
-	rsbne   \irqnr, \irqnr, #32
-	.endm
-
-	.macro arch_ret_to_user, tmp1, tmp2
-	mrc	p15, 0, \tmp1, c15, c1, 0
-	ands	\tmp2, \tmp1, #(1 << 6)
-	bicne	\tmp1, \tmp1, #(1 << 6)
-	mcrne	p15, 0, \tmp1, c15, c1, 0	@ Disable cp6 access
-	.endm
diff --git a/arch/arm/mach-iop32x/iop3xx.h b/arch/arm/mach-iop32x/iop3xx.h
index 46b4b34a4ad2..a6ec7ebadb35 100644
--- a/arch/arm/mach-iop32x/iop3xx.h
+++ b/arch/arm/mach-iop32x/iop3xx.h
@@ -225,6 +225,7 @@ extern int iop3xx_get_init_atu(void);
 #include <linux/reboot.h>
 
 void iop3xx_map_io(void);
+void iop_enable_cp6(void);
 void iop_init_cp6_handler(void);
 void iop_init_time(unsigned long tickrate);
 void iop3xx_restart(enum reboot_mode, const char *);
diff --git a/arch/arm/mach-iop32x/irq.c b/arch/arm/mach-iop32x/irq.c
index d1e8824cbd82..b820839eaae8 100644
--- a/arch/arm/mach-iop32x/irq.c
+++ b/arch/arm/mach-iop32x/irq.c
@@ -29,6 +29,15 @@ static void intstr_write(u32 val)
 	asm volatile("mcr p6, 0, %0, c4, c0, 0" : : "r" (val));
 }
 
+static u32 iintsrc_read(void)
+{
+	int irq;
+
+	asm volatile("mrc p6, 0, %0, c8, c0, 0" : "=r" (irq));
+
+	return irq;
+}
+
 static void
 iop32x_irq_mask(struct irq_data *d)
 {
@@ -50,11 +59,25 @@ struct irq_chip ext_chip = {
 	.irq_unmask	= iop32x_irq_unmask,
 };
 
+void iop_handle_irq(struct pt_regs *regs)
+{
+	u32 mask;
+
+	iop_enable_cp6();
+
+	do {
+		mask = iintsrc_read();
+		if (mask)
+			generic_handle_irq(fls(mask));
+	} while (mask);
+}
+
 void __init iop32x_init_irq(void)
 {
 	int i;
 
 	iop_init_cp6_handler();
+	set_handle_irq(iop_handle_irq);
 
 	intctl_write(0);
 	intstr_write(0);
-- 
2.30.2


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[PATCH v4 06/15] ARM: remove old-style irq entry

[Ard Biesheuvel]

From: Arnd Bergmann <arnd@arndb.de>

The last user of arch_irq_handler_default is gone now, so the
entry-macro-multi.S file and all references to mach/entry-macro.S can
be removed, as well as the asm_do_IRQ() entrypoint into the interrupt
handling routines implemented in C.

Note: The ARMv7-M entry still uses its own top-level IRQ entry, calling
nvic_handle_irq() from assembly. This could be changed to go through
generic_handle_arch_irq() as well, but it's unclear to me if there are
any benefits.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
[ardb: keep irq_handler macro as it carries all the IRQ stack handling]
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Marc Zyngier <maz@kernel.org>
Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
---
 arch/arm/Kconfig                         | 14 ++------------
 arch/arm/include/asm/entry-macro-multi.S | 16 ----------------
 arch/arm/include/asm/irq.h               |  1 -
 arch/arm/include/asm/mach/arch.h         |  2 --
 arch/arm/kernel/entry-armv.S             |  8 --------
 arch/arm/kernel/irq.c                    | 17 -----------------
 6 files changed, 2 insertions(+), 56 deletions(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index d9ba6961b295..b0e403076227 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -58,6 +58,7 @@ config ARM
 	select GENERIC_CPU_AUTOPROBE
 	select GENERIC_EARLY_IOREMAP
 	select GENERIC_IDLE_POLL_SETUP
+	select GENERIC_IRQ_MULTI_HANDLER if MMU
 	select GENERIC_IRQ_PROBE
 	select GENERIC_IRQ_SHOW
 	select GENERIC_IRQ_SHOW_LEVEL
@@ -320,7 +321,6 @@ config ARCH_MULTIPLATFORM
 	select AUTO_ZRELADDR
 	select TIMER_OF
 	select COMMON_CLK
-	select GENERIC_IRQ_MULTI_HANDLER
 	select HAVE_PCI
 	select PCI_DOMAINS_GENERIC if PCI
 	select SPARSE_IRQ
@@ -344,7 +344,6 @@ config ARCH_EP93XX
 	select ARM_AMBA
 	imply ARM_PATCH_PHYS_VIRT
 	select ARM_VIC
-	select GENERIC_IRQ_MULTI_HANDLER
 	select AUTO_ZRELADDR
 	select CLKSRC_MMIO
 	select CPU_ARM920T
@@ -359,7 +358,6 @@ config ARCH_FOOTBRIDGE
 	select FOOTBRIDGE
 	select NEED_MACH_IO_H if !MMU
 	select NEED_MACH_MEMORY_H
-	select GENERIC_IRQ_MULTI_HANDLER
 	help
 	  Support for systems based on the DC21285 companion chip
 	  ("FootBridge"), such as the Simtec CATS and the Rebel NetWinder.
@@ -368,7 +366,6 @@ config ARCH_IOP32X
 	bool "IOP32x-based"
 	depends on MMU
 	select CPU_XSCALE
-	select GENERIC_IRQ_MULTI_HANDLER
 	select GPIO_IOP
 	select GPIOLIB
 	select FORCE_PCI
@@ -384,7 +381,6 @@ config ARCH_IXP4XX
 	select ARCH_SUPPORTS_BIG_ENDIAN
 	select CPU_XSCALE
 	select DMABOUNCE if PCI
-	select GENERIC_IRQ_MULTI_HANDLER
 	select GPIO_IXP4XX
 	select GPIOLIB
 	select HAVE_PCI
@@ -400,7 +396,6 @@ config ARCH_IXP4XX
 config ARCH_DOVE
 	bool "Marvell Dove"
 	select CPU_PJ4
-	select GENERIC_IRQ_MULTI_HANDLER
 	select GPIOLIB
 	select HAVE_PCI
 	select MVEBU_MBUS
@@ -423,7 +418,6 @@ config ARCH_PXA
 	select CLKSRC_MMIO
 	select TIMER_OF
 	select CPU_XSCALE if !CPU_XSC3
-	select GENERIC_IRQ_MULTI_HANDLER
 	select GPIO_PXA
 	select GPIOLIB
 	select IRQ_DOMAIN
@@ -442,7 +436,6 @@ config ARCH_RPC
 	select ARM_HAS_SG_CHAIN
 	select CPU_SA110
 	select FIQ
-	select GENERIC_IRQ_MULTI_HANDLER
 	select HAVE_PATA_PLATFORM
 	select ISA_DMA_API
 	select LEGACY_TIMER_TICK
@@ -463,7 +456,6 @@ config ARCH_SA1100
 	select COMMON_CLK
 	select CPU_FREQ
 	select CPU_SA1100
-	select GENERIC_IRQ_MULTI_HANDLER
 	select GPIOLIB
 	select IRQ_DOMAIN
 	select ISA
@@ -478,7 +470,6 @@ config ARCH_S3C24XX
 	select CLKSRC_SAMSUNG_PWM
 	select GPIO_SAMSUNG
 	select GPIOLIB
-	select GENERIC_IRQ_MULTI_HANDLER
 	select HAVE_S3C2410_I2C if I2C
 	select NEED_MACH_IO_H
 	select S3C2410_WATCHDOG
@@ -497,7 +488,6 @@ config ARCH_OMAP1
 	select ARCH_OMAP
 	select CLKSRC_MMIO
 	select GENERIC_IRQ_CHIP
-	select GENERIC_IRQ_MULTI_HANDLER
 	select GPIOLIB
 	select HAVE_LEGACY_CLK
 	select IRQ_DOMAIN
@@ -1168,7 +1158,7 @@ config CURRENT_POINTER_IN_TPIDRURO
 
 config IRQSTACKS
 	def_bool y
-	depends on GENERIC_IRQ_MULTI_HANDLER && THREAD_INFO_IN_TASK
+	depends on THREAD_INFO_IN_TASK
 	select HAVE_IRQ_EXIT_ON_IRQ_STACK
 	select HAVE_SOFTIRQ_ON_OWN_STACK
 
diff --git a/arch/arm/include/asm/entry-macro-multi.S b/arch/arm/include/asm/entry-macro-multi.S
deleted file mode 100644
index 24486dad9e19..000000000000
--- a/arch/arm/include/asm/entry-macro-multi.S
+++ /dev/null
@@ -1,16 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-#include <asm/assembler.h>
-
-/*
- * Interrupt handling.  Preserves r7, r8, r9
- */
-	.macro	arch_irq_handler_default
-	get_irqnr_preamble r6, lr
-1:	get_irqnr_and_base r0, r2, r6, lr
-	movne	r1, sp
-	@
-	@ routine called with r0 = irq number, r1 = struct pt_regs *
-	@
-	badrne	lr, 1b
-	bne	asm_do_IRQ
-	.endm
diff --git a/arch/arm/include/asm/irq.h b/arch/arm/include/asm/irq.h
index 1cbcc462b07e..a7c2337b0c7d 100644
--- a/arch/arm/include/asm/irq.h
+++ b/arch/arm/include/asm/irq.h
@@ -26,7 +26,6 @@
 struct irqaction;
 struct pt_regs;
 
-extern void asm_do_IRQ(unsigned int, struct pt_regs *);
 void handle_IRQ(unsigned int, struct pt_regs *);
 void init_IRQ(void);
 
diff --git a/arch/arm/include/asm/mach/arch.h b/arch/arm/include/asm/mach/arch.h
index eec0c0bda766..9349e7a82c9c 100644
--- a/arch/arm/include/asm/mach/arch.h
+++ b/arch/arm/include/asm/mach/arch.h
@@ -56,9 +56,7 @@ struct machine_desc {
 	void			(*init_time)(void);
 	void			(*init_machine)(void);
 	void			(*init_late)(void);
-#ifdef CONFIG_GENERIC_IRQ_MULTI_HANDLER
 	void			(*handle_irq)(struct pt_regs *);
-#endif
 	void			(*restart)(enum reboot_mode, const char *);
 };
 
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index 5fb7465d14d9..9744d087ee9f 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -19,9 +19,6 @@
 #include <asm/glue-df.h>
 #include <asm/glue-pf.h>
 #include <asm/vfpmacros.h>
-#ifndef CONFIG_GENERIC_IRQ_MULTI_HANDLER
-#include <mach/entry-macro.S>
-#endif
 #include <asm/thread_notify.h>
 #include <asm/unwind.h>
 #include <asm/unistd.h>
@@ -30,14 +27,12 @@
 #include <asm/uaccess-asm.h>
 
 #include "entry-header.S"
-#include <asm/entry-macro-multi.S>
 #include <asm/probes.h>
 
 /*
  * Interrupt handling.
  */
 	.macro	irq_handler, from_user:req
-#ifdef CONFIG_GENERIC_IRQ_MULTI_HANDLER
 	mov	r0, sp
 #ifdef CONFIG_IRQSTACKS
 	mov_l	r2, irq_stack_ptr	@ Take base address
@@ -92,9 +87,6 @@ UNWIND(	.setfp	fpreg, sp		)
 	mov	sp, r9			@ Restore original SP
 #endif // CONFIG_UNWINDER_ARM
 #endif // CONFIG_IRQSTACKS
-#else
-	arch_irq_handler_default
-#endif
 	.endm
 
 	.macro	pabt_helper
diff --git a/arch/arm/kernel/irq.c b/arch/arm/kernel/irq.c
index 5deb40f39999..5c6f8d11a3ce 100644
--- a/arch/arm/kernel/irq.c
+++ b/arch/arm/kernel/irq.c
@@ -120,23 +120,6 @@ void handle_IRQ(unsigned int irq, struct pt_regs *regs)
 		ack_bad_irq(irq);
 }
 
-/*
- * asm_do_IRQ is the interface to be used from assembly code.
- */
-asmlinkage void __exception_irq_entry
-asm_do_IRQ(unsigned int irq, struct pt_regs *regs)
-{
-	struct pt_regs *old_regs;
-
-	irq_enter();
-	old_regs = set_irq_regs(regs);
-
-	handle_IRQ(irq, regs);
-
-	set_irq_regs(old_regs);
-	irq_exit();
-}
-
 void __init init_IRQ(void)
 {
 	int ret;
-- 
2.30.2


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[PATCH v4 07/15] irqchip: nvic: Use GENERIC_IRQ_MULTI_HANDLER

[Ard Biesheuvel]

From: Vladimir Murzin <vladimir.murzin@arm.com>

Rather then restructuring the ARMv7M entrly logic per TODO, just move
NVIC to GENERIC_IRQ_MULTI_HANDLER.

Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Marc Zyngier <maz@kernel.org>
Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M
---
 arch/arm/include/asm/v7m.h  |  3 ++-
 arch/arm/kernel/entry-v7m.S | 10 +++------
 drivers/irqchip/Kconfig     |  1 +
 drivers/irqchip/irq-nvic.c  | 22 +++++---------------
 4 files changed, 11 insertions(+), 25 deletions(-)

diff --git a/arch/arm/include/asm/v7m.h b/arch/arm/include/asm/v7m.h
index 2cb00d15831b..4512f7e1918f 100644
--- a/arch/arm/include/asm/v7m.h
+++ b/arch/arm/include/asm/v7m.h
@@ -13,6 +13,7 @@
 #define V7M_SCB_ICSR_PENDSVSET			(1 << 28)
 #define V7M_SCB_ICSR_PENDSVCLR			(1 << 27)
 #define V7M_SCB_ICSR_RETTOBASE			(1 << 11)
+#define V7M_SCB_ICSR_VECTACTIVE			0x000001ff
 
 #define V7M_SCB_VTOR			0x08
 
@@ -38,7 +39,7 @@
 #define V7M_SCB_SHCSR_MEMFAULTENA		(1 << 16)
 
 #define V7M_xPSR_FRAMEPTRALIGN			0x00000200
-#define V7M_xPSR_EXCEPTIONNO			0x000001ff
+#define V7M_xPSR_EXCEPTIONNO			V7M_SCB_ICSR_VECTACTIVE
 
 /*
  * When branching to an address that has bits [31:28] == 0xf an exception return
diff --git a/arch/arm/kernel/entry-v7m.S b/arch/arm/kernel/entry-v7m.S
index 7bde93c10962..520dd43e7e08 100644
--- a/arch/arm/kernel/entry-v7m.S
+++ b/arch/arm/kernel/entry-v7m.S
@@ -39,14 +39,10 @@ __irq_entry:
 	@
 	@ Invoke the IRQ handler
 	@
-	mrs	r0, ipsr
-	ldr	r1, =V7M_xPSR_EXCEPTIONNO
-	and	r0, r1
-	sub	r0, #16
-	mov	r1, sp
+	mov	r0, sp
 	stmdb	sp!, {lr}
-	@ routine called with r0 = irq number, r1 = struct pt_regs *
-	bl	nvic_handle_irq
+	@ routine called with r0 = struct pt_regs *
+	bl	generic_handle_arch_irq
 
 	pop	{lr}
 	@
diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
index 7038957f4a77..488eaa14d3a7 100644
--- a/drivers/irqchip/Kconfig
+++ b/drivers/irqchip/Kconfig
@@ -58,6 +58,7 @@ config ARM_NVIC
 	bool
 	select IRQ_DOMAIN_HIERARCHY
 	select GENERIC_IRQ_CHIP
+	select GENERIC_IRQ_MULTI_HANDLER
 
 config ARM_VIC
 	bool
diff --git a/drivers/irqchip/irq-nvic.c b/drivers/irqchip/irq-nvic.c
index 63bac3f78863..c0de696b3823 100644
--- a/drivers/irqchip/irq-nvic.c
+++ b/drivers/irqchip/irq-nvic.c
@@ -37,25 +37,12 @@
 
 static struct irq_domain *nvic_irq_domain;
 
-static void __nvic_handle_irq(irq_hw_number_t hwirq)
+static void __irq_entry nvic_handle_irq(struct pt_regs *regs)
 {
-	generic_handle_domain_irq(nvic_irq_domain, hwirq);
-}
+	unsigned long icsr = readl_relaxed(BASEADDR_V7M_SCB + V7M_SCB_ICSR);
+	irq_hw_number_t hwirq = (icsr & V7M_SCB_ICSR_VECTACTIVE) - 16;
 
-/*
- * TODO: restructure the ARMv7M entry logic so that this entry logic can live
- * in arch code.
- */
-asmlinkage void __exception_irq_entry
-nvic_handle_irq(irq_hw_number_t hwirq, struct pt_regs *regs)
-{
-	struct pt_regs *old_regs;
-
-	irq_enter();
-	old_regs = set_irq_regs(regs);
-	__nvic_handle_irq(hwirq);
-	set_irq_regs(old_regs);
-	irq_exit();
+	generic_handle_domain_irq(nvic_irq_domain, hwirq);
 }
 
 static int nvic_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
@@ -141,6 +128,7 @@ static int __init nvic_of_init(struct device_node *node,
 	for (i = 0; i < irqs; i += 4)
 		writel_relaxed(0, nvic_base + NVIC_IPR + i);
 
+	set_handle_irq(nvic_handle_irq);
 	return 0;
 }
 IRQCHIP_DECLARE(armv7m_nvic, "arm,armv7m-nvic", nvic_of_init);
-- 
2.30.2


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[PATCH v4 08/15] ARM: entry: preserve thread_info pointer in switch_to

[Ard Biesheuvel]

Tweak the UP stack protector handling code so that the thread info
pointer is preserved in R7 until set_current is called. This is needed
for a subsequent patch that implements THREAD_INFO_IN_TASK and
set_current for UP as well.

This also means we will prefer the per-task protector on UP systems that
implement the thread ID registers, so tweak the preprocessor
conditionals to reflect this.

Acked-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Marc Zyngier <maz@kernel.org>
Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M
---
 arch/arm/kernel/entry-armv.S | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index 9744d087ee9f..1a6cf711a3b4 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -806,16 +806,16 @@ ENTRY(__switch_to)
 	ldr	r6, [r2, #TI_CPU_DOMAIN]
 #endif
 	switch_tls r1, r4, r5, r3, r7
-#if defined(CONFIG_STACKPROTECTOR) && !defined(CONFIG_SMP)
-	ldr	r7, [r2, #TI_TASK]
+#if defined(CONFIG_STACKPROTECTOR) && !defined(CONFIG_SMP) && \
+    !defined(CONFIG_STACKPROTECTOR_PER_TASK)
+	ldr	r9, [r2, #TI_TASK]
 	ldr	r8, =__stack_chk_guard
 	.if (TSK_STACK_CANARY > IMM12_MASK)
-	add	r7, r7, #TSK_STACK_CANARY & ~IMM12_MASK
+	add	r9, r9, #TSK_STACK_CANARY & ~IMM12_MASK
 	.endif
-	ldr	r7, [r7, #TSK_STACK_CANARY & IMM12_MASK]
-#elif defined(CONFIG_CURRENT_POINTER_IN_TPIDRURO)
-	mov	r7, r2				@ Preserve 'next'
+	ldr	r9, [r9, #TSK_STACK_CANARY & IMM12_MASK]
 #endif
+	mov	r7, r2				@ Preserve 'next'
 #ifdef CONFIG_CPU_USE_DOMAINS
 	mcr	p15, 0, r6, c3, c0, 0		@ Set domain register
 #endif
@@ -824,8 +824,9 @@ ENTRY(__switch_to)
 	ldr	r0, =thread_notify_head
 	mov	r1, #THREAD_NOTIFY_SWITCH
 	bl	atomic_notifier_call_chain
-#if defined(CONFIG_STACKPROTECTOR) && !defined(CONFIG_SMP)
-	str	r7, [r8]
+#if defined(CONFIG_STACKPROTECTOR) && !defined(CONFIG_SMP) && \
+    !defined(CONFIG_STACKPROTECTOR_PER_TASK)
+	str	r9, [r8]
 #endif
 	mov	r0, r5
 #if !defined(CONFIG_THUMB2_KERNEL) && !defined(CONFIG_VMAP_STACK)
-- 
2.30.2


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[PATCH v4 09/15] ARM: module: implement support for PC-relative group relocations

[Ard Biesheuvel]

Add support for the R_ARM_ALU_PC_Gn_NC and R_ARM_LDR_PC_G2 group
relocations [0] so we can use them in modules. These will be used to
load the current task pointer from a global variable without having to
rely on a literal pool entry to carry the address of this variable,
which may have a significant negative impact on cache utilization for
variables that are used often and in many different places, as each
occurrence will result in a literal pool entry and therefore a line in
the D-cache.

[0] 'ELF for the ARM architecture'
    https://github.com/ARM-software/abi-aa/releases

Acked-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Marc Zyngier <maz@kernel.org>
Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M
---
 arch/arm/include/asm/elf.h |  3 +
 arch/arm/kernel/module.c   | 85 ++++++++++++++++++++
 2 files changed, 88 insertions(+)

diff --git a/arch/arm/include/asm/elf.h b/arch/arm/include/asm/elf.h
index b8102a6ddf16..d68101655b74 100644
--- a/arch/arm/include/asm/elf.h
+++ b/arch/arm/include/asm/elf.h
@@ -61,6 +61,9 @@ typedef struct user_fp elf_fpregset_t;
 #define R_ARM_MOVT_ABS		44
 #define R_ARM_MOVW_PREL_NC	45
 #define R_ARM_MOVT_PREL		46
+#define R_ARM_ALU_PC_G0_NC	57
+#define R_ARM_ALU_PC_G1_NC	59
+#define R_ARM_LDR_PC_G2		63
 
 #define R_ARM_THM_CALL		10
 #define R_ARM_THM_JUMP24	30
diff --git a/arch/arm/kernel/module.c b/arch/arm/kernel/module.c
index beac45e89ba6..4d33a7acf617 100644
--- a/arch/arm/kernel/module.c
+++ b/arch/arm/kernel/module.c
@@ -68,6 +68,42 @@ bool module_exit_section(const char *name)
 		strstarts(name, ".ARM.exidx.exit");
 }
 
+/*
+ * This implements the partitioning algorithm for group relocations as
+ * documented in the ARM AArch32 ELF psABI (IHI 0044).
+ *
+ * A single PC-relative symbol reference is divided in up to 3 add or subtract
+ * operations, where the final one could be incorporated into a load/store
+ * instruction with immediate offset. E.g.,
+ *
+ *   ADD	Rd, PC, #...		or	ADD	Rd, PC, #...
+ *   ADD	Rd, Rd, #...			ADD	Rd, Rd, #...
+ *   LDR	Rd, [Rd, #...]			ADD	Rd, Rd, #...
+ *
+ * The latter has a guaranteed range of only 16 MiB (3x8 == 24 bits), so it is
+ * of limited use in the kernel. However, the ADD/ADD/LDR combo has a range of
+ * -/+ 256 MiB, (2x8 + 12 == 28 bits), which means it has sufficient range for
+ * any in-kernel symbol reference (unless module PLTs are being used).
+ *
+ * The main advantage of this approach over the typical pattern using a literal
+ * load is that literal loads may miss in the D-cache, and generally lead to
+ * lower cache efficiency for variables that are referenced often from many
+ * different places in the code.
+ */
+static u32 get_group_rem(u32 group, u32 *offset)
+{
+	u32 val = *offset;
+	u32 shift;
+	do {
+		shift = val ? (31 - __fls(val)) & ~1 : 32;
+		*offset = val;
+		if (!val)
+			break;
+		val &= 0xffffff >> shift;
+	} while (group--);
+	return shift;
+}
+
 int
 apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex,
 	       unsigned int relindex, struct module *module)
@@ -82,6 +118,7 @@ apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex,
 		unsigned long loc;
 		Elf32_Sym *sym;
 		const char *symname;
+		u32 shift, group = 1;
 		s32 offset;
 		u32 tmp;
 #ifdef CONFIG_THUMB2_KERNEL
@@ -212,6 +249,54 @@ apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex,
 			*(u32 *)loc = __opcode_to_mem_arm(tmp);
 			break;
 
+		case R_ARM_ALU_PC_G0_NC:
+			group = 0;
+			fallthrough;
+		case R_ARM_ALU_PC_G1_NC:
+			tmp = __mem_to_opcode_arm(*(u32 *)loc);
+			offset = ror32(tmp & 0xff, (tmp & 0xf00) >> 7);
+			if (tmp & BIT(22))
+				offset = -offset;
+			offset += sym->st_value - loc;
+			if (offset < 0) {
+				offset = -offset;
+				tmp = (tmp & ~BIT(23)) | BIT(22); // SUB opcode
+			} else {
+				tmp = (tmp & ~BIT(22)) | BIT(23); // ADD opcode
+			}
+
+			shift = get_group_rem(group, &offset);
+			if (shift < 24) {
+				offset >>= 24 - shift;
+				offset |= (shift + 8) << 7;
+			}
+			*(u32 *)loc = __opcode_to_mem_arm((tmp & ~0xfff) | offset);
+			break;
+
+		case R_ARM_LDR_PC_G2:
+			tmp = __mem_to_opcode_arm(*(u32 *)loc);
+			offset = tmp & 0xfff;
+			if (~tmp & BIT(23))		// U bit cleared?
+				offset = -offset;
+			offset += sym->st_value - loc;
+			if (offset < 0) {
+				offset = -offset;
+				tmp &= ~BIT(23);	// clear U bit
+			} else {
+				tmp |= BIT(23);		// set U bit
+			}
+			get_group_rem(2, &offset);
+
+			if (offset > 0xfff) {
+				pr_err("%s: section %u reloc %u sym '%s': relocation %u out of range (%#lx -> %#x)\n",
+				       module->name, relindex, i, symname,
+				       ELF32_R_TYPE(rel->r_info), loc,
+				       sym->st_value);
+				return -ENOEXEC;
+			}
+			*(u32 *)loc = __opcode_to_mem_arm((tmp & ~0xfff) | offset);
+			break;
+
 #ifdef CONFIG_THUMB2_KERNEL
 		case R_ARM_THM_CALL:
 		case R_ARM_THM_JUMP24:
-- 
2.30.2


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[PATCH v4 10/15] ARM: assembler: add optimized ldr/str macros to load variables from memory

[Ard Biesheuvel]

We will be adding variable loads to various hot paths, so it makes sense
to add a helper macro that can load variables from asm code without the
use of literal pool entries. On v7 or later, we can simply use MOVW/MOVT
pairs, but on earlier cores, this requires a bit of hackery to emit a
instruction sequence that implements this using a sequence of ADD/LDR
instructions.

Acked-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Marc Zyngier <maz@kernel.org>
Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M
---
 arch/arm/include/asm/assembler.h | 45 ++++++++++++++++++--
 arch/arm/kernel/entry-armv.S     |  2 +-
 arch/arm/kernel/entry-header.S   |  2 +-
 3 files changed, 43 insertions(+), 6 deletions(-)

diff --git a/arch/arm/include/asm/assembler.h b/arch/arm/include/asm/assembler.h
index 1b9d4df331aa..2095638b7140 100644
--- a/arch/arm/include/asm/assembler.h
+++ b/arch/arm/include/asm/assembler.h
@@ -568,12 +568,12 @@ THUMB(	orr	\reg , \reg , #PSR_T_BIT	)
 	/*
 	 * mov_l - move a constant value or [relocated] address into a register
 	 */
-	.macro		mov_l, dst:req, imm:req
+	.macro		mov_l, dst:req, imm:req, cond
 	.if		__LINUX_ARM_ARCH__ < 7
-	ldr		\dst, =\imm
+	ldr\cond	\dst, =\imm
 	.else
-	movw		\dst, #:lower16:\imm
-	movt		\dst, #:upper16:\imm
+	movw\cond	\dst, #:lower16:\imm
+	movt\cond	\dst, #:upper16:\imm
 	.endif
 	.endm
 
@@ -611,6 +611,43 @@ THUMB(	orr	\reg , \reg , #PSR_T_BIT	)
 	__adldst_l	str, \src, \sym, \tmp, \cond
 	.endm
 
+	.macro		__ldst_va, op, reg, tmp, sym, cond
+#if __LINUX_ARM_ARCH__ >= 7 || \
+    (defined(MODULE) && defined(CONFIG_ARM_MODULE_PLTS)) || \
+    (defined(CONFIG_LD_IS_LLD) && CONFIG_LLD_VERSION < 140000)
+	mov_l		\tmp, \sym, \cond
+	\op\cond	\reg, [\tmp]
+#else
+	/*
+	 * Avoid a literal load, by emitting a sequence of ADD/LDR instructions
+	 * with the appropriate relocations. The combined sequence has a range
+	 * of -/+ 256 MiB, which should be sufficient for the core kernel and
+	 * for modules loaded into the module region.
+	 */
+	.globl		\sym
+	.reloc		.L0_\@, R_ARM_ALU_PC_G0_NC, \sym
+	.reloc		.L1_\@, R_ARM_ALU_PC_G1_NC, \sym
+	.reloc		.L2_\@, R_ARM_LDR_PC_G2, \sym
+.L0_\@: sub\cond	\tmp, pc, #8
+.L1_\@: sub\cond	\tmp, \tmp, #4
+.L2_\@: \op\cond	\reg, [\tmp, #0]
+#endif
+	.endm
+
+	/*
+	 * ldr_va - load a 32-bit word from the virtual address of \sym
+	 */
+	.macro		ldr_va, rd:req, sym:req, cond
+	__ldst_va	ldr, \rd, \rd, \sym, \cond
+	.endm
+
+	/*
+	 * str_va - store a 32-bit word to the virtual address of \sym
+	 */
+	.macro		str_va, rn:req, sym:req, tmp:req, cond
+	__ldst_va	str, \rn, \tmp, \sym, \cond
+	.endm
+
 	/*
 	 * rev_l - byte-swap a 32-bit value
 	 *
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index 1a6cf711a3b4..7f7ac963445c 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -53,7 +53,7 @@ UNWIND(	.setfp	fpreg, sp		)
 	subs	r2, sp, r0		@ SP above bottom of IRQ stack?
 	rsbscs	r2, r2, #THREAD_SIZE	@ ... and below the top?
 #ifdef CONFIG_VMAP_STACK
-	ldr_l	r2, high_memory, cc	@ End of the linear region
+	ldr_va	r2, high_memory, cc	@ End of the linear region
 	cmpcc	r2, r0			@ Stack pointer was below it?
 #endif
 	movcs	sp, r0			@ If so, revert to incoming SP
diff --git a/arch/arm/kernel/entry-header.S b/arch/arm/kernel/entry-header.S
index 81df2a3561ca..268f7f4c5c05 100644
--- a/arch/arm/kernel/entry-header.S
+++ b/arch/arm/kernel/entry-header.S
@@ -445,7 +445,7 @@ THUMB(	it	ne						)
 	@ in such cases so just carry on.
 	@
 	str	ip, [r0, #12]			@ Stash IP on the mode stack
-	ldr_l	ip, high_memory			@ Start of VMALLOC space
+	ldr_va	ip, high_memory			@ Start of VMALLOC space
 ARM(	cmp	sp, ip			)	@ SP in vmalloc space?
 THUMB(	cmp	r1, ip			)
 THUMB(	itt	lo			)
-- 
2.30.2


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[PATCH v4 11/15] ARM: percpu: add SMP_ON_UP support

[Ard Biesheuvel]

Permit the use of the TPIDRPRW system register for carrying the per-CPU
offset in generic SMP configurations that also target non-SMP capable
ARMv6 cores. This uses the SMP_ON_UP code patching framework to turn all
TPIDRPRW accesses into reads/writes of entry #0 in the __per_cpu_offset
array.

While at it, switch over some existing direct TPIDRPRW accesses in asm
code to invocations of a new helper that is patched in the same way when
necessary.

Note that CPU_V6+SMP without SMP_ON_UP results in a kernel that does not
boot on v6 CPUs without SMP extensions, so add this dependency to
Kconfig as well.

Acked-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Marc Zyngier <maz@kernel.org>
Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M
---
 arch/arm/include/asm/assembler.h | 59 +++++++++++++++++++-
 arch/arm/include/asm/insn.h      | 24 ++++++++
 arch/arm/include/asm/percpu.h    | 25 ++++++++-
 arch/arm/kernel/entry-armv.S     | 16 +-----
 arch/arm/kernel/sleep.S          |  4 +-
 arch/arm/mm/Kconfig              |  1 +
 6 files changed, 107 insertions(+), 22 deletions(-)

diff --git a/arch/arm/include/asm/assembler.h b/arch/arm/include/asm/assembler.h
index 2095638b7140..f9b3dd0e9ef5 100644
--- a/arch/arm/include/asm/assembler.h
+++ b/arch/arm/include/asm/assembler.h
@@ -220,9 +220,7 @@ THUMB(	fpreg	.req	r7	)
 
 	.macro	reload_current, t1:req, t2:req
 #ifdef CONFIG_CURRENT_POINTER_IN_TPIDRURO
-	adr_l	\t1, __entry_task		@ get __entry_task base address
-	mrc	p15, 0, \t2, c13, c0, 4		@ get per-CPU offset
-	ldr	\t1, [\t1, \t2]			@ load variable
+	ldr_this_cpu \t1, __entry_task, \t1, \t2
 	mcr	p15, 0, \t1, c13, c0, 3		@ store in TPIDRURO
 #endif
 	.endm
@@ -312,6 +310,26 @@ THUMB(	fpreg	.req	r7	)
 #define ALT_UP_B(label) b label
 #endif
 
+	/*
+	 * this_cpu_offset - load the per-CPU offset of this CPU into
+	 * 		     register 'rd'
+	 */
+	.macro		this_cpu_offset, rd:req
+#ifdef CONFIG_SMP
+ALT_SMP(mrc		p15, 0, \rd, c13, c0, 4)
+#ifdef CONFIG_CPU_V6
+ALT_UP_B(.L1_\@)
+.L0_\@:
+	.subsection	1
+.L1_\@: ldr_va		\rd, __per_cpu_offset
+	b		.L0_\@
+	.previous
+#endif
+#else
+	mov		\rd, #0
+#endif
+	.endm
+
 /*
  * Instruction barrier
  */
@@ -648,6 +666,41 @@ THUMB(	orr	\reg , \reg , #PSR_T_BIT	)
 	__ldst_va	str, \rn, \tmp, \sym, \cond
 	.endm
 
+	/*
+	 * ldr_this_cpu_armv6 - Load a 32-bit word from the per-CPU variable 'sym',
+	 *			without using a temp register. Supported in ARM mode
+	 *			only.
+	 */
+	.macro		ldr_this_cpu_armv6, rd:req, sym:req
+	this_cpu_offset	\rd
+	.globl		\sym
+	.reloc		.L0_\@, R_ARM_ALU_PC_G0_NC, \sym
+	.reloc		.L1_\@, R_ARM_ALU_PC_G1_NC, \sym
+	.reloc		.L2_\@, R_ARM_LDR_PC_G2, \sym
+	add		\rd, \rd, pc
+.L0_\@: sub		\rd, \rd, #4
+.L1_\@: sub		\rd, \rd, #0
+.L2_\@: ldr		\rd, [\rd, #4]
+	.endm
+
+	/*
+	 * ldr_this_cpu - Load a 32-bit word from the per-CPU variable 'sym'
+	 *		  into register 'rd', which may be the stack pointer,
+	 *		  using 't1' and 't2' as general temp registers. These
+	 *		  are permitted to overlap with 'rd' if != sp
+	 */
+	.macro		ldr_this_cpu, rd:req, sym:req, t1:req, t2:req
+#if __LINUX_ARM_ARCH__ >= 7 || \
+    (defined(MODULE) && defined(CONFIG_ARM_MODULE_PLTS)) || \
+    (defined(CONFIG_LD_IS_LLD) && CONFIG_LLD_VERSION < 140000)
+	this_cpu_offset	\t1
+	mov_l		\t2, \sym
+	ldr		\rd, [\t1, \t2]
+#else
+	ldr_this_cpu_armv6 \rd, \sym
+#endif
+	.endm
+
 	/*
 	 * rev_l - byte-swap a 32-bit value
 	 *
diff --git a/arch/arm/include/asm/insn.h b/arch/arm/include/asm/insn.h
index 5475cbf9fb6b..a160ed3ea427 100644
--- a/arch/arm/include/asm/insn.h
+++ b/arch/arm/include/asm/insn.h
@@ -2,6 +2,30 @@
 #ifndef __ASM_ARM_INSN_H
 #define __ASM_ARM_INSN_H
 
+#include <linux/types.h>
+
+/*
+ * Avoid a literal load by emitting a sequence of ADD/LDR instructions with the
+ * appropriate relocations. The combined sequence has a range of -/+ 256 MiB,
+ * which should be sufficient for the core kernel as well as modules loaded
+ * into the module region. (Not supported by LLD before release 14)
+ */
+#if !(defined(MODULE) && defined(CONFIG_ARM_MODULE_PLTS)) && \
+    !(defined(CONFIG_LD_IS_LLD) && CONFIG_LLD_VERSION < 140000)
+#define LOAD_SYM_ARMV6(reg, sym)					\
+	"	.globl	" #sym "				\n\t"	\
+	"	.reloc	10f, R_ARM_ALU_PC_G0_NC, " #sym "	\n\t"	\
+	"	.reloc	11f, R_ARM_ALU_PC_G1_NC, " #sym "	\n\t"	\
+	"	.reloc	12f, R_ARM_LDR_PC_G2, " #sym "		\n\t"	\
+	"10:	sub	" #reg ", pc, #8			\n\t"	\
+	"11:	sub	" #reg ", " #reg ", #4			\n\t"	\
+	"12:	ldr	" #reg ", [" #reg ", #0]		\n\t"
+#else
+#define LOAD_SYM_ARMV6(reg, sym)					\
+	"	ldr	" #reg ", =" #sym "			\n\t"	\
+	"	ldr	" #reg ", [" #reg "]			\n\t"
+#endif
+
 static inline unsigned long
 arm_gen_nop(void)
 {
diff --git a/arch/arm/include/asm/percpu.h b/arch/arm/include/asm/percpu.h
index e2fcb3cfd3de..a4a0d38d016a 100644
--- a/arch/arm/include/asm/percpu.h
+++ b/arch/arm/include/asm/percpu.h
@@ -5,15 +5,22 @@
 #ifndef _ASM_ARM_PERCPU_H_
 #define _ASM_ARM_PERCPU_H_
 
+#include <asm/insn.h>
+
 register unsigned long current_stack_pointer asm ("sp");
 
 /*
  * Same as asm-generic/percpu.h, except that we store the per cpu offset
  * in the TPIDRPRW. TPIDRPRW only exists on V6K and V7
  */
-#if defined(CONFIG_SMP) && !defined(CONFIG_CPU_V6)
+#ifdef CONFIG_SMP
 static inline void set_my_cpu_offset(unsigned long off)
 {
+	extern unsigned int smp_on_up;
+
+	if (IS_ENABLED(CONFIG_CPU_V6) && !smp_on_up)
+		return;
+
 	/* Set TPIDRPRW */
 	asm volatile("mcr p15, 0, %0, c13, c0, 4" : : "r" (off) : "memory");
 }
@@ -27,8 +34,20 @@ static inline unsigned long __my_cpu_offset(void)
 	 * We want to allow caching the value, so avoid using volatile and
 	 * instead use a fake stack read to hazard against barrier().
 	 */
-	asm("mrc p15, 0, %0, c13, c0, 4" : "=r" (off)
-		: "Q" (*(const unsigned long *)current_stack_pointer));
+	asm("0:	mrc p15, 0, %0, c13, c0, 4			\n\t"
+#ifdef CONFIG_CPU_V6
+	    "1:							\n\t"
+	    "	.subsection 1					\n\t"
+	    "2: " LOAD_SYM_ARMV6(%0, __per_cpu_offset) "	\n\t"
+	    "	b	1b					\n\t"
+	    "	.previous					\n\t"
+	    "	.pushsection \".alt.smp.init\", \"a\"		\n\t"
+	    "	.long	0b - .					\n\t"
+	    "	b	. + (2b - 0b)				\n\t"
+	    "	.popsection					\n\t"
+#endif
+	     : "=r" (off)
+	     : "Q" (*(const unsigned long *)current_stack_pointer));
 
 	return off;
 }
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index 7f7ac963445c..43d917f0d9a9 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -35,15 +35,14 @@
 	.macro	irq_handler, from_user:req
 	mov	r0, sp
 #ifdef CONFIG_IRQSTACKS
-	mov_l	r2, irq_stack_ptr	@ Take base address
-	mrc	p15, 0, r3, c13, c0, 4	@ Get CPU offset
 #ifdef CONFIG_UNWINDER_ARM
 	mov	fpreg, sp		@ Preserve original SP
 #else
 	mov	r8, fp			@ Preserve original FP
 	mov	r9, sp			@ Preserve original SP
 #endif
-	ldr	sp, [r2, r3]		@ Load SP from per-CPU var
+	ldr_this_cpu sp, irq_stack_ptr, r2, r3
+
 	.if	\from_user == 0
 UNWIND(	.setfp	fpreg, sp		)
 	@
@@ -876,16 +875,7 @@ __bad_stack:
 THUMB(	bx	pc		)
 THUMB(	nop			)
 THUMB(	.arm			)
-	mrc	p15, 0, ip, c13, c0, 4		@ Get per-CPU offset
-
-	.globl	overflow_stack_ptr
-	.reloc	0f, R_ARM_ALU_PC_G0_NC, overflow_stack_ptr
-	.reloc	1f, R_ARM_ALU_PC_G1_NC, overflow_stack_ptr
-	.reloc	2f, R_ARM_LDR_PC_G2, overflow_stack_ptr
-	add	ip, ip, pc
-0:	add	ip, ip, #-4
-1:	add	ip, ip, #0
-2:	ldr	ip, [ip, #4]
+	ldr_this_cpu_armv6 ip, overflow_stack_ptr
 
 	str	sp, [ip, #-4]!			@ Preserve original SP value
 	mov	sp, ip				@ Switch to overflow stack
diff --git a/arch/arm/kernel/sleep.S b/arch/arm/kernel/sleep.S
index 803b51e5cba0..f909baf17912 100644
--- a/arch/arm/kernel/sleep.S
+++ b/arch/arm/kernel/sleep.S
@@ -71,9 +71,7 @@ ENTRY(__cpu_suspend)
 	@ Run the suspend code from the overflow stack so we don't have to rely
 	@ on vmalloc-to-phys conversions anywhere in the arch suspend code.
 	@ The original SP value captured in R5 will be restored on the way out.
-	mov_l	r6, overflow_stack_ptr	@ Base pointer
-	mrc	p15, 0, r7, c13, c0, 4	@ Get per-CPU offset
-	ldr	sp, [r6, r7]		@ Address of this CPU's overflow stack
+	ldr_this_cpu sp, overflow_stack_ptr, r6, r7
 #endif
 	add	r4, r4, #12		@ Space for pgd, virt sp, phys resume fn
 	sub	sp, sp, r4		@ allocate CPU state on stack
diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig
index 58afba346729..a91ff22c6c2e 100644
--- a/arch/arm/mm/Kconfig
+++ b/arch/arm/mm/Kconfig
@@ -386,6 +386,7 @@ config CPU_V6
 	select CPU_PABRT_V6
 	select CPU_THUMB_CAPABLE
 	select CPU_TLB_V6 if MMU
+	select SMP_ON_UP if SMP
 
 # ARMv6k
 config CPU_V6K
-- 
2.30.2


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[PATCH v4 12/15] ARM: use TLS register for 'current' on !SMP as well

[Ard Biesheuvel]

Enable the use of the TLS register to hold the 'current' pointer also on
non-SMP configurations that target v6k or later CPUs. This will permit
the use of THREAD_INFO_IN_TASK as well as IRQ stacks and vmap'ed stacks
for such configurations.

Acked-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Nicolas Pitre <nico@fluxnic.net>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Marc Zyngier <maz@kernel.org>
Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M
---
 arch/arm/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index b0e403076227..5ad2151c43dd 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1154,7 +1154,7 @@ config SMP_ON_UP
 
 config CURRENT_POINTER_IN_TPIDRURO
 	def_bool y
-	depends on SMP && CPU_32v6K && !CPU_V6
+	depends on CPU_32v6K && !CPU_V6
 
 config IRQSTACKS
 	def_bool y
-- 
2.30.2


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[PATCH v4 13/15] ARM: smp: defer TPIDRURO update for SMP v6 configurations too

[Ard Biesheuvel]

Defer TPIDURO updates for user space until exit also for CPU_V6+SMP
configurations so that we can decide at runtime whether to use it to
carry the current pointer, provided that we are running on a CPU that
actually implements this register. This is needed for
THREAD_INFO_IN_TASK support for UP systems, which requires that all SMP
capable systems use the TPIDRURO based access to 'current' as the only
remaining alternative will be a global variable which only works on UP.

Acked-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Marc Zyngier <maz@kernel.org>
Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M
---
 arch/arm/include/asm/tls.h     | 13 +++++++------
 arch/arm/kernel/entry-header.S | 11 ++++++++++-
 2 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/arch/arm/include/asm/tls.h b/arch/arm/include/asm/tls.h
index c3296499176c..d712c170c095 100644
--- a/arch/arm/include/asm/tls.h
+++ b/arch/arm/include/asm/tls.h
@@ -18,13 +18,14 @@
 	.endm
 
 	.macro switch_tls_v6, base, tp, tpuser, tmp1, tmp2
-	ldr	\tmp1, =elf_hwcap
-	ldr	\tmp1, [\tmp1, #0]
+	ldr_va	\tmp1, elf_hwcap
 	mov	\tmp2, #0xffff0fff
 	tst	\tmp1, #HWCAP_TLS		@ hardware TLS available?
 	streq	\tp, [\tmp2, #-15]		@ set TLS value at 0xffff0ff0
 	mrcne	p15, 0, \tmp2, c13, c0, 2	@ get the user r/w register
+#ifndef CONFIG_SMP
 	mcrne	p15, 0, \tp, c13, c0, 3		@ yes, set TLS register
+#endif
 	mcrne	p15, 0, \tpuser, c13, c0, 2	@ set user r/w register
 	strne	\tmp2, [\base, #TI_TP_VALUE + 4] @ save it
 	.endm
@@ -43,7 +44,7 @@
 #elif defined(CONFIG_CPU_V6)
 #define tls_emu		0
 #define has_tls_reg		(elf_hwcap & HWCAP_TLS)
-#define defer_tls_reg_update	0
+#define defer_tls_reg_update	IS_ENABLED(CONFIG_SMP)
 #define switch_tls	switch_tls_v6
 #elif defined(CONFIG_CPU_32v6K)
 #define tls_emu		0
@@ -81,11 +82,11 @@ static inline void set_tls(unsigned long val)
 	 */
 	barrier();
 
-	if (!tls_emu && !defer_tls_reg_update) {
-		if (has_tls_reg) {
+	if (!tls_emu) {
+		if (has_tls_reg && !defer_tls_reg_update) {
 			asm("mcr p15, 0, %0, c13, c0, 3"
 			    : : "r" (val));
-		} else {
+		} else if (!has_tls_reg) {
 #ifdef CONFIG_KUSER_HELPERS
 			/*
 			 * User space must never try to access this
diff --git a/arch/arm/kernel/entry-header.S b/arch/arm/kernel/entry-header.S
index 268f7f4c5c05..cb82ff5adec1 100644
--- a/arch/arm/kernel/entry-header.S
+++ b/arch/arm/kernel/entry-header.S
@@ -292,12 +292,21 @@
 
 
 	.macro	restore_user_regs, fast = 0, offset = 0
-#if defined(CONFIG_CPU_32v6K) && !defined(CONFIG_CPU_V6)
+#if defined(CONFIG_CPU_32v6K) || defined(CONFIG_SMP)
+#if defined(CONFIG_CPU_V6) && defined(CONFIG_SMP)
+ALT_SMP(b	.L1_\@	)
+ALT_UP( nop		)
+	ldr_va	r1, elf_hwcap
+	tst	r1, #HWCAP_TLS			@ hardware TLS available?
+	beq	.L2_\@
+.L1_\@:
+#endif
 	@ The TLS register update is deferred until return to user space so we
 	@ can use it for other things while running in the kernel
 	get_thread_info r1
 	ldr	r1, [r1, #TI_TP_VALUE]
 	mcr	p15, 0, r1, c13, c0, 3		@ set TLS register
+.L2_\@:
 #endif
 
 	uaccess_enable r1, isb=0
-- 
2.30.2


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[PATCH v4 14/15] ARM: implement THREAD_INFO_IN_TASK for uniprocessor systems

[Ard Biesheuvel]

On UP systems, only a single task can be 'current' at the same time,
which means we can use a global variable to track it. This means we can
also enable THREAD_INFO_IN_TASK for those systems, as in that case,
thread_info is accessed via current rather than the other way around,
removing the need to store thread_info at the base of the task stack.
This, in turn, permits us to enable IRQ stacks and vmap'ed stacks on UP
systems as well.

To partially mitigate the performance overhead of this arrangement, use
a ADD/ADD/LDR sequence with the appropriate PC-relative group
relocations to load the value of current when needed. This means that
accessing current will still only require a single load as before,
avoiding the need for a literal to carry the address of the global
variable in each function. However, accessing thread_info will now
require this load as well.

Acked-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Marc Zyngier <maz@kernel.org>
Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M
---
 arch/arm/Kconfig                   |  8 +-
 arch/arm/include/asm/assembler.h   | 83 +++++++++++++-------
 arch/arm/include/asm/current.h     | 37 +++++----
 arch/arm/include/asm/switch_to.h   |  3 +-
 arch/arm/include/asm/thread_info.h | 27 -------
 arch/arm/kernel/asm-offsets.c      |  3 -
 arch/arm/kernel/entry-armv.S       | 11 +--
 arch/arm/kernel/entry-v7m.S        | 10 ++-
 arch/arm/kernel/head-common.S      |  4 +-
 arch/arm/kernel/process.c          |  7 +-
 arch/arm/kernel/smp.c              | 11 +++
 arch/arm/kernel/traps.c            |  4 +
 12 files changed, 116 insertions(+), 92 deletions(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 5ad2151c43dd..50ae5286f59b 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -127,8 +127,8 @@ config ARM
 	select PERF_USE_VMALLOC
 	select RTC_LIB
 	select SYS_SUPPORTS_APM_EMULATION
-	select THREAD_INFO_IN_TASK if CURRENT_POINTER_IN_TPIDRURO
-	select HAVE_ARCH_VMAP_STACK if MMU && THREAD_INFO_IN_TASK && (!LD_IS_LLD || LLD_VERSION >= 140000)
+	select THREAD_INFO_IN_TASK
+	select HAVE_ARCH_VMAP_STACK if MMU && (!LD_IS_LLD || LLD_VERSION >= 140000)
 	select TRACE_IRQFLAGS_SUPPORT if !CPU_V7M
 	# Above selects are sorted alphabetically; please add new ones
 	# according to that.  Thanks.
@@ -1158,7 +1158,7 @@ config CURRENT_POINTER_IN_TPIDRURO
 
 config IRQSTACKS
 	def_bool y
-	depends on THREAD_INFO_IN_TASK
+	depends on MMU
 	select HAVE_IRQ_EXIT_ON_IRQ_STACK
 	select HAVE_SOFTIRQ_ON_OWN_STACK
 
@@ -1608,7 +1608,7 @@ config CC_HAVE_STACKPROTECTOR_TLS
 
 config STACKPROTECTOR_PER_TASK
 	bool "Use a unique stack canary value for each task"
-	depends on STACKPROTECTOR && THREAD_INFO_IN_TASK && !XIP_DEFLATED_DATA
+	depends on STACKPROTECTOR && CURRENT_POINTER_IN_TPIDRURO && !XIP_DEFLATED_DATA
 	depends on GCC_PLUGINS || CC_HAVE_STACKPROTECTOR_TLS
 	select GCC_PLUGIN_ARM_SSP_PER_TASK if !CC_HAVE_STACKPROTECTOR_TLS
 	default y
diff --git a/arch/arm/include/asm/assembler.h b/arch/arm/include/asm/assembler.h
index f9b3dd0e9ef5..59d7b9e81934 100644
--- a/arch/arm/include/asm/assembler.h
+++ b/arch/arm/include/asm/assembler.h
@@ -203,41 +203,12 @@ THUMB(	fpreg	.req	r7	)
 	.endm
 	.endr
 
-	.macro	get_current, rd
-#ifdef CONFIG_CURRENT_POINTER_IN_TPIDRURO
-	mrc	p15, 0, \rd, c13, c0, 3		@ get TPIDRURO register
-#else
-	get_thread_info \rd
-	ldr	\rd, [\rd, #TI_TASK]
-#endif
-	.endm
-
-	.macro	set_current, rn
-#ifdef CONFIG_CURRENT_POINTER_IN_TPIDRURO
-	mcr	p15, 0, \rn, c13, c0, 3		@ set TPIDRURO register
-#endif
-	.endm
-
-	.macro	reload_current, t1:req, t2:req
-#ifdef CONFIG_CURRENT_POINTER_IN_TPIDRURO
-	ldr_this_cpu \t1, __entry_task, \t1, \t2
-	mcr	p15, 0, \t1, c13, c0, 3		@ store in TPIDRURO
-#endif
-	.endm
-
 /*
  * Get current thread_info.
  */
 	.macro	get_thread_info, rd
-#ifdef CONFIG_THREAD_INFO_IN_TASK
 	/* thread_info is the first member of struct task_struct */
 	get_current \rd
-#else
- ARM(	mov	\rd, sp, lsr #THREAD_SIZE_ORDER + PAGE_SHIFT	)
- THUMB(	mov	\rd, sp			)
- THUMB(	lsr	\rd, \rd, #THREAD_SIZE_ORDER + PAGE_SHIFT	)
-	mov	\rd, \rd, lsl #THREAD_SIZE_ORDER + PAGE_SHIFT
-#endif
 	.endm
 
 /*
@@ -330,6 +301,60 @@ ALT_UP_B(.L1_\@)
 #endif
 	.endm
 
+	/*
+	 * set_current - store the task pointer of this CPU's current task
+	 */
+	.macro		set_current, rn:req, tmp:req
+#if defined(CONFIG_CURRENT_POINTER_IN_TPIDRURO) || defined(CONFIG_SMP)
+9998:	mcr		p15, 0, \rn, c13, c0, 3		@ set TPIDRURO register
+#ifdef CONFIG_CPU_V6
+ALT_UP_B(.L0_\@)
+	.subsection	1
+.L0_\@: str_va		\rn, __current, \tmp
+	b		.L1_\@
+	.previous
+.L1_\@:
+#endif
+#else
+	str_va		\rn, __current, \tmp
+#endif
+	.endm
+
+	/*
+	 * get_current - load the task pointer of this CPU's current task
+	 */
+	.macro		get_current, rd:req
+#if defined(CONFIG_CURRENT_POINTER_IN_TPIDRURO) || defined(CONFIG_SMP)
+9998:	mrc		p15, 0, \rd, c13, c0, 3		@ get TPIDRURO register
+#ifdef CONFIG_CPU_V6
+ALT_UP_B(.L0_\@)
+	.subsection	1
+.L0_\@: ldr_va		\rd, __current
+	b		.L1_\@
+	.previous
+.L1_\@:
+#endif
+#else
+	ldr_va		\rd, __current
+#endif
+	.endm
+
+	/*
+	 * reload_current - reload the task pointer of this CPU's current task
+	 *		    into the TLS register
+	 */
+	.macro		reload_current, t1:req, t2:req
+#if defined(CONFIG_CURRENT_POINTER_IN_TPIDRURO) || defined(CONFIG_SMP)
+#ifdef CONFIG_CPU_V6
+ALT_SMP(nop)
+ALT_UP_B(.L0_\@)
+#endif
+	ldr_this_cpu	\t1, __entry_task, \t1, \t2
+	mcr		p15, 0, \t1, c13, c0, 3		@ store in TPIDRURO
+.L0_\@:
+#endif
+	.endm
+
 /*
  * Instruction barrier
  */
diff --git a/arch/arm/include/asm/current.h b/arch/arm/include/asm/current.h
index 6bf0aad672c3..69ecf4c6c725 100644
--- a/arch/arm/include/asm/current.h
+++ b/arch/arm/include/asm/current.h
@@ -8,25 +8,18 @@
 #define _ASM_ARM_CURRENT_H
 
 #ifndef __ASSEMBLY__
+#include <asm/insn.h>
 
 struct task_struct;
 
-static inline void set_current(struct task_struct *cur)
-{
-	if (!IS_ENABLED(CONFIG_CURRENT_POINTER_IN_TPIDRURO))
-		return;
-
-	/* Set TPIDRURO */
-	asm("mcr p15, 0, %0, c13, c0, 3" :: "r"(cur) : "memory");
-}
+extern struct task_struct *__current;
 
-#ifdef CONFIG_CURRENT_POINTER_IN_TPIDRURO
-
-static inline struct task_struct *get_current(void)
+static inline __attribute_const__ struct task_struct *get_current(void)
 {
 	struct task_struct *cur;
 
 #if __has_builtin(__builtin_thread_pointer) && \
+    defined(CONFIG_CURRENT_POINTER_IN_TPIDRURO) && \
     !(defined(CONFIG_THUMB2_KERNEL) && \
       defined(CONFIG_CC_IS_CLANG) && CONFIG_CLANG_VERSION < 130001)
 	/*
@@ -39,16 +32,30 @@ static inline struct task_struct *get_current(void)
 	 * https://github.com/ClangBuiltLinux/linux/issues/1485
 	 */
 	cur = __builtin_thread_pointer();
+#elif defined(CONFIG_CURRENT_POINTER_IN_TPIDRURO) || defined(CONFIG_SMP)
+	asm("0:	mrc p15, 0, %0, c13, c0, 3			\n\t"
+#ifdef CONFIG_CPU_V6
+	    "1:							\n\t"
+	    "	.subsection 1					\n\t"
+	    "2: " LOAD_SYM_ARMV6(%0, __current) "		\n\t"
+	    "	b	1b					\n\t"
+	    "	.previous					\n\t"
+	    "	.pushsection \".alt.smp.init\", \"a\"		\n\t"
+	    "	.long	0b - .					\n\t"
+	    "	b	. + (2b - 0b)				\n\t"
+	    "	.popsection					\n\t"
+#endif
+	    : "=r"(cur));
+#elif __LINUX_ARM_ARCH__>=7 || \
+      (defined(MODULE) && defined(CONFIG_ARM_MODULE_PLTS))
+	cur = __current;
 #else
-	asm("mrc p15, 0, %0, c13, c0, 3" : "=r"(cur));
+	asm(LOAD_SYM_ARMV6(%0, __current) : "=r"(cur));
 #endif
 	return cur;
 }
 
 #define current get_current()
-#else
-#include <asm-generic/current.h>
-#endif /* CONFIG_CURRENT_POINTER_IN_TPIDRURO */
 
 #endif /* __ASSEMBLY__ */
 
diff --git a/arch/arm/include/asm/switch_to.h b/arch/arm/include/asm/switch_to.h
index b55c7b2755e4..a482c99934ff 100644
--- a/arch/arm/include/asm/switch_to.h
+++ b/arch/arm/include/asm/switch_to.h
@@ -40,7 +40,8 @@ static inline void set_ti_cpu(struct task_struct *p)
 do {									\
 	__complete_pending_tlbi();					\
 	set_ti_cpu(next);						\
-	if (IS_ENABLED(CONFIG_CURRENT_POINTER_IN_TPIDRURO))		\
+	if (IS_ENABLED(CONFIG_CURRENT_POINTER_IN_TPIDRURO) ||		\
+	    IS_ENABLED(CONFIG_SMP))					\
 		__this_cpu_write(__entry_task, next);			\
 	last = __switch_to(prev,task_thread_info(prev), task_thread_info(next));	\
 } while (0)
diff --git a/arch/arm/include/asm/thread_info.h b/arch/arm/include/asm/thread_info.h
index 004b89d86224..aecc403b2880 100644
--- a/arch/arm/include/asm/thread_info.h
+++ b/arch/arm/include/asm/thread_info.h
@@ -62,9 +62,6 @@ struct cpu_context_save {
 struct thread_info {
 	unsigned long		flags;		/* low level flags */
 	int			preempt_count;	/* 0 => preemptable, <0 => bug */
-#ifndef CONFIG_THREAD_INFO_IN_TASK
-	struct task_struct	*task;		/* main task structure */
-#endif
 	__u32			cpu;		/* cpu */
 	__u32			cpu_domain;	/* cpu domain */
 	struct cpu_context_save	cpu_context;	/* cpu context */
@@ -80,39 +77,15 @@ struct thread_info {
 
 #define INIT_THREAD_INFO(tsk)						\
 {									\
-	INIT_THREAD_INFO_TASK(tsk)					\
 	.flags		= 0,						\
 	.preempt_count	= INIT_PREEMPT_COUNT,				\
 }
 
-#ifdef CONFIG_THREAD_INFO_IN_TASK
-#define INIT_THREAD_INFO_TASK(tsk)
-
 static inline struct task_struct *thread_task(struct thread_info* ti)
 {
 	return (struct task_struct *)ti;
 }
 
-#else
-#define INIT_THREAD_INFO_TASK(tsk)	.task = &(tsk),
-
-static inline struct task_struct *thread_task(struct thread_info* ti)
-{
-	return ti->task;
-}
-
-/*
- * how to get the thread information struct from C
- */
-static inline struct thread_info *current_thread_info(void) __attribute_const__;
-
-static inline struct thread_info *current_thread_info(void)
-{
-	return (struct thread_info *)
-		(current_stack_pointer & ~(THREAD_SIZE - 1));
-}
-#endif
-
 #define thread_saved_pc(tsk)	\
 	((unsigned long)(task_thread_info(tsk)->cpu_context.pc))
 #define thread_saved_sp(tsk)	\
diff --git a/arch/arm/kernel/asm-offsets.c b/arch/arm/kernel/asm-offsets.c
index 645845e4982a..2c8d76fd7c66 100644
--- a/arch/arm/kernel/asm-offsets.c
+++ b/arch/arm/kernel/asm-offsets.c
@@ -43,9 +43,6 @@ int main(void)
   BLANK();
   DEFINE(TI_FLAGS,		offsetof(struct thread_info, flags));
   DEFINE(TI_PREEMPT,		offsetof(struct thread_info, preempt_count));
-#ifndef CONFIG_THREAD_INFO_IN_TASK
-  DEFINE(TI_TASK,		offsetof(struct thread_info, task));
-#endif
   DEFINE(TI_CPU,		offsetof(struct thread_info, cpu));
   DEFINE(TI_CPU_DOMAIN,		offsetof(struct thread_info, cpu_domain));
   DEFINE(TI_CPU_SAVE,		offsetof(struct thread_info, cpu_context));
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index 43d917f0d9a9..b58bda51e4b8 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -807,12 +807,13 @@ ENTRY(__switch_to)
 	switch_tls r1, r4, r5, r3, r7
 #if defined(CONFIG_STACKPROTECTOR) && !defined(CONFIG_SMP) && \
     !defined(CONFIG_STACKPROTECTOR_PER_TASK)
-	ldr	r9, [r2, #TI_TASK]
 	ldr	r8, =__stack_chk_guard
 	.if (TSK_STACK_CANARY > IMM12_MASK)
-	add	r9, r9, #TSK_STACK_CANARY & ~IMM12_MASK
-	.endif
+	add	r9, r2, #TSK_STACK_CANARY & ~IMM12_MASK
 	ldr	r9, [r9, #TSK_STACK_CANARY & IMM12_MASK]
+	.else
+	ldr	r9, [r2, #TSK_STACK_CANARY & IMM12_MASK]
+	.endif
 #endif
 	mov	r7, r2				@ Preserve 'next'
 #ifdef CONFIG_CPU_USE_DOMAINS
@@ -829,7 +830,7 @@ ENTRY(__switch_to)
 #endif
 	mov	r0, r5
 #if !defined(CONFIG_THUMB2_KERNEL) && !defined(CONFIG_VMAP_STACK)
-	set_current r7
+	set_current r7, r8
 	ldmia	r4, {r4 - sl, fp, sp, pc}	@ Load all regs saved previously
 #else
 	mov	r1, r7
@@ -851,7 +852,7 @@ ENTRY(__switch_to)
 	@ switches us to another stack, with few other side effects. In order
 	@ to prevent this distinction from causing any inconsistencies, let's
 	@ keep the 'set_current' call as close as we can to the update of SP.
-	set_current r1
+	set_current r1, r2
 	mov	sp, ip
 	ret	lr
 #endif
diff --git a/arch/arm/kernel/entry-v7m.S b/arch/arm/kernel/entry-v7m.S
index 520dd43e7e08..4e0d318b67c6 100644
--- a/arch/arm/kernel/entry-v7m.S
+++ b/arch/arm/kernel/entry-v7m.S
@@ -97,15 +97,17 @@ ENTRY(__switch_to)
 	str	sp, [ip], #4
 	str	lr, [ip], #4
 	mov	r5, r0
+	mov	r6, r2			@ Preserve 'next'
 	add	r4, r2, #TI_CPU_SAVE
 	ldr	r0, =thread_notify_head
 	mov	r1, #THREAD_NOTIFY_SWITCH
 	bl	atomic_notifier_call_chain
-	mov	ip, r4
 	mov	r0, r5
-	ldmia	ip!, {r4 - r11}		@ Load all regs saved previously
-	ldr	sp, [ip]
-	ldr	pc, [ip, #4]!
+	mov	r1, r6
+	ldmia	r4, {r4 - r12, lr}	@ Load all regs saved previously
+	set_current r1, r2
+	mov	sp, ip
+	bx	lr
 	.fnend
 ENDPROC(__switch_to)
 
diff --git a/arch/arm/kernel/head-common.S b/arch/arm/kernel/head-common.S
index da18e0a17dc2..42cae73fcc19 100644
--- a/arch/arm/kernel/head-common.S
+++ b/arch/arm/kernel/head-common.S
@@ -105,10 +105,8 @@ __mmap_switched:
 	mov	r1, #0
 	bl	__memset			@ clear .bss
 
-#ifdef CONFIG_CURRENT_POINTER_IN_TPIDRURO
 	adr_l	r0, init_task			@ get swapper task_struct
-	set_current r0
-#endif
+	set_current r0, r1
 
 	ldmia	r4, {r0, r1, r2, r3}
 	str	r9, [r0]			@ Save processor ID
diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index d47159f3791c..0617af11377f 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -36,7 +36,7 @@
 
 #include "signal.h"
 
-#ifdef CONFIG_CURRENT_POINTER_IN_TPIDRURO
+#if defined(CONFIG_CURRENT_POINTER_IN_TPIDRURO) || defined(CONFIG_SMP)
 DEFINE_PER_CPU(struct task_struct *, __entry_task);
 #endif
 
@@ -46,6 +46,11 @@ unsigned long __stack_chk_guard __read_mostly;
 EXPORT_SYMBOL(__stack_chk_guard);
 #endif
 
+#ifndef CONFIG_CURRENT_POINTER_IN_TPIDRURO
+asmlinkage struct task_struct *__current;
+EXPORT_SYMBOL(__current);
+#endif
+
 static const char *processor_modes[] __maybe_unused = {
   "USER_26", "FIQ_26" , "IRQ_26" , "SVC_26" , "UK4_26" , "UK5_26" , "UK6_26" , "UK7_26" ,
   "UK8_26" , "UK9_26" , "UK10_26", "UK11_26", "UK12_26", "UK13_26", "UK14_26", "UK15_26",
diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index 9c55ca915ba4..951559e5bea3 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -403,6 +403,17 @@ static void smp_store_cpu_info(unsigned int cpuid)
 	check_cpu_icache_size(cpuid);
 }
 
+static void set_current(struct task_struct *cur)
+{
+	if (!IS_ENABLED(CONFIG_CURRENT_POINTER_IN_TPIDRURO) && !is_smp()) {
+		__current = cur;
+		return;
+	}
+
+	/* Set TPIDRURO */
+	asm("mcr p15, 0, %0, c13, c0, 3" :: "r"(cur) : "memory");
+}
+
 /*
  * This is the secondary CPU boot entry.  We're using this CPUs
  * idle thread stack, but a set of temporary page tables.
diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
index b28a705c49cb..3f38357efc46 100644
--- a/arch/arm/kernel/traps.c
+++ b/arch/arm/kernel/traps.c
@@ -865,7 +865,9 @@ early_initcall(allocate_overflow_stacks);
 asmlinkage void handle_bad_stack(struct pt_regs *regs)
 {
 	unsigned long tsk_stk = (unsigned long)current->stack;
+#ifdef CONFIG_IRQSTACKS
 	unsigned long irq_stk = (unsigned long)this_cpu_read(irq_stack_ptr);
+#endif
 	unsigned long ovf_stk = (unsigned long)this_cpu_read(overflow_stack_ptr);
 
 	console_verbose();
@@ -873,8 +875,10 @@ asmlinkage void handle_bad_stack(struct pt_regs *regs)
 
 	pr_emerg("Task stack:     [0x%08lx..0x%08lx]\n",
 		 tsk_stk, tsk_stk + THREAD_SIZE);
+#ifdef CONFIG_IRQSTACKS
 	pr_emerg("IRQ stack:      [0x%08lx..0x%08lx]\n",
 		 irq_stk - THREAD_SIZE, irq_stk);
+#endif
 	pr_emerg("Overflow stack: [0x%08lx..0x%08lx]\n",
 		 ovf_stk - OVERFLOW_STACK_SIZE, ovf_stk);
 
-- 
2.30.2


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[PATCH v4 15/15] ARM: v7m: enable support for IRQ stacks

[Ard Biesheuvel]

Enable support for IRQ stacks on !MMU, and add the code to the IRQ entry
path to switch to the IRQ stack if not running from it already.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Marc Zyngier <maz@kernel.org>
Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M
---
 arch/arm/Kconfig            |  1 -
 arch/arm/kernel/entry-v7m.S | 17 +++++++++++++++--
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 50ae5286f59b..359a3b85c8b3 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1158,7 +1158,6 @@ config CURRENT_POINTER_IN_TPIDRURO
 
 config IRQSTACKS
 	def_bool y
-	depends on MMU
 	select HAVE_IRQ_EXIT_ON_IRQ_STACK
 	select HAVE_SOFTIRQ_ON_OWN_STACK
 
diff --git a/arch/arm/kernel/entry-v7m.S b/arch/arm/kernel/entry-v7m.S
index 4e0d318b67c6..de8a60363c85 100644
--- a/arch/arm/kernel/entry-v7m.S
+++ b/arch/arm/kernel/entry-v7m.S
@@ -40,11 +40,24 @@ __irq_entry:
 	@ Invoke the IRQ handler
 	@
 	mov	r0, sp
-	stmdb	sp!, {lr}
+	ldr_this_cpu sp, irq_stack_ptr, r1, r2
+
+	@
+	@ If we took the interrupt while running in the kernel, we may already
+	@ be using the IRQ stack, so revert to the original value in that case.
+	@
+	subs	r2, sp, r0		@ SP above bottom of IRQ stack?
+	rsbscs	r2, r2, #THREAD_SIZE	@ ... and below the top?
+	movcs	sp, r0
+
+	push	{r0, lr}		@ preserve LR and original SP
+
 	@ routine called with r0 = struct pt_regs *
 	bl	generic_handle_arch_irq
 
-	pop	{lr}
+	pop	{r0, lr}
+	mov	sp, r0
+
 	@
 	@ Check for any pending work if returning to user
 	@
-- 
2.30.2


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