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0b58725fb9
The MMU off code path in ll_get_coherency_base() attempts to decide
whether the coherency fabric is mapped by testing the value of
coherency_base, which carries its virtual address if its mapped, and
0x0 otherwise.
However, what the code actually does is take the virtual address of
the coherency_base symbol, and compare it with 0x0, which are never
equal, and so the branch is never taken. In fact, with the MMU off,
dereferencing the VA of coherency_base is not possible to begin with,
nor can its value be relied upon with the MMU off since it is not
cleaned to the Dcache as is done with coherency_phys_base in
armada_370_coherency_init().
Instead, the value of coherency_phys_base is returned, which results
in the correct behavior since it will be 0x0 as well if the coherency
fabric is not mapped, and it is accessible with the MMU off. So just
drop the comparison and the branch.
Fixes: 30cdef9710 ("ARM: mvebu: make the coherency_ll.S functions work with no coherency fabric")
Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Gregory CLEMENT <gregory.clement@bootlin.com>
Cc: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>
162 lines
4.2 KiB
ArmAsm
162 lines
4.2 KiB
ArmAsm
/*
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* Coherency fabric: low level functions
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*
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* Copyright (C) 2012 Marvell
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*
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* Gregory CLEMENT <gregory.clement@free-electrons.com>
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*
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* This file is licensed under the terms of the GNU General Public
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* License version 2. This program is licensed "as is" without any
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* warranty of any kind, whether express or implied.
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*
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* This file implements the assembly function to add a CPU to the
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* coherency fabric. This function is called by each of the secondary
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* CPUs during their early boot in an SMP kernel, this why this
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* function have to callable from assembly. It can also be called by a
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* primary CPU from C code during its boot.
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*/
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#include <linux/linkage.h>
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#define ARMADA_XP_CFB_CTL_REG_OFFSET 0x0
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#define ARMADA_XP_CFB_CFG_REG_OFFSET 0x4
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#include <asm/assembler.h>
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#include <asm/cp15.h>
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.text
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/*
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* Returns the coherency base address in r1 (r0 is untouched), or 0 if
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* the coherency fabric is not enabled.
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*/
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ENTRY(ll_get_coherency_base)
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mrc p15, 0, r1, c1, c0, 0
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tst r1, #CR_M @ Check MMU bit enabled
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bne 1f
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/*
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* MMU is disabled, use the physical address of the coherency
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* base address, (or 0x0 if the coherency fabric is not mapped)
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*/
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adr r1, 3f
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ldr r3, [r1]
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ldr r1, [r1, r3]
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b 2f
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1:
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/*
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* MMU is enabled, use the virtual address of the coherency
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* base address.
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*/
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ldr r1, =coherency_base
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ldr r1, [r1]
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2:
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ret lr
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ENDPROC(ll_get_coherency_base)
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/*
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* Returns the coherency CPU mask in r3 (r0 is untouched). This
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* coherency CPU mask can be used with the coherency fabric
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* configuration and control registers. Note that the mask is already
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* endian-swapped as appropriate so that the calling functions do not
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* have to care about endianness issues while accessing the coherency
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* fabric registers
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*/
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ENTRY(ll_get_coherency_cpumask)
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mrc p15, 0, r3, cr0, cr0, 5
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and r3, r3, #15
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mov r2, #(1 << 24)
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lsl r3, r2, r3
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ARM_BE8(rev r3, r3)
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ret lr
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ENDPROC(ll_get_coherency_cpumask)
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/*
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* ll_add_cpu_to_smp_group(), ll_enable_coherency() and
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* ll_disable_coherency() use the strex/ldrex instructions while the
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* MMU can be disabled. The Armada XP SoC has an exclusive monitor
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* that tracks transactions to Device and/or SO memory and thanks to
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* that, exclusive transactions are functional even when the MMU is
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* disabled.
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*/
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ENTRY(ll_add_cpu_to_smp_group)
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/*
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* As r0 is not modified by ll_get_coherency_base() and
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* ll_get_coherency_cpumask(), we use it to temporarly save lr
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* and avoid it being modified by the branch and link
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* calls. This function is used very early in the secondary
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* CPU boot, and no stack is available at this point.
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*/
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mov r0, lr
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bl ll_get_coherency_base
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/* Bail out if the coherency is not enabled */
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cmp r1, #0
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reteq r0
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bl ll_get_coherency_cpumask
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mov lr, r0
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add r0, r1, #ARMADA_XP_CFB_CFG_REG_OFFSET
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1:
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ldrex r2, [r0]
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orr r2, r2, r3
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strex r1, r2, [r0]
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cmp r1, #0
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bne 1b
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ret lr
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ENDPROC(ll_add_cpu_to_smp_group)
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ENTRY(ll_enable_coherency)
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/*
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* As r0 is not modified by ll_get_coherency_base() and
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* ll_get_coherency_cpumask(), we use it to temporarly save lr
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* and avoid it being modified by the branch and link
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* calls. This function is used very early in the secondary
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* CPU boot, and no stack is available at this point.
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*/
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mov r0, lr
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bl ll_get_coherency_base
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/* Bail out if the coherency is not enabled */
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cmp r1, #0
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reteq r0
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bl ll_get_coherency_cpumask
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mov lr, r0
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add r0, r1, #ARMADA_XP_CFB_CTL_REG_OFFSET
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1:
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ldrex r2, [r0]
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orr r2, r2, r3
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strex r1, r2, [r0]
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cmp r1, #0
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bne 1b
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dsb
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mov r0, #0
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ret lr
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ENDPROC(ll_enable_coherency)
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ENTRY(ll_disable_coherency)
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/*
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* As r0 is not modified by ll_get_coherency_base() and
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* ll_get_coherency_cpumask(), we use it to temporarly save lr
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* and avoid it being modified by the branch and link
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* calls. This function is used very early in the secondary
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* CPU boot, and no stack is available at this point.
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*/
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mov r0, lr
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bl ll_get_coherency_base
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/* Bail out if the coherency is not enabled */
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cmp r1, #0
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reteq r0
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bl ll_get_coherency_cpumask
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mov lr, r0
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add r0, r1, #ARMADA_XP_CFB_CTL_REG_OFFSET
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1:
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ldrex r2, [r0]
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bic r2, r2, r3
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strex r1, r2, [r0]
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cmp r1, #0
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bne 1b
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dsb
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ret lr
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ENDPROC(ll_disable_coherency)
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.align 2
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3:
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.long coherency_phys_base - .
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