forked from Minki/linux
4827d0cf74
When DSP extensions are present, some of the regular integer instructions such as DIV, MACD etc are executed in the DSP unit with semantics alterable by flags in DSP_CTRL aux register. This register is writable by userspace and thus can potentially affect corresponding instructions in kernel code, intentionally or otherwise. So safegaurd kernel by effectively disabling DSP_CTRL upon bootup and every entry to kernel. Do note that for this config we simply zero out the DSP_CTRL reg assuming userspace doesn't really care about DSP. The next patch caters to the DSP aware userspace where this reg is saved/restored upon kernel entry/exit. Reviewed-by: Vineet Gupta <vgupta@synopsys.com> Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com> Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
151 lines
3.9 KiB
ArmAsm
151 lines
3.9 KiB
ArmAsm
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* ARC CPU startup Code
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*
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* Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
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*
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* Vineetg: Dec 2007
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* -Check if we are running on Simulator or on real hardware
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* to skip certain things during boot on simulator
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*/
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#include <linux/linkage.h>
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#include <asm/asm-offsets.h>
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#include <asm/entry.h>
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#include <asm/arcregs.h>
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#include <asm/cache.h>
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#include <asm/dsp-impl.h>
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#include <asm/irqflags.h>
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.macro CPU_EARLY_SETUP
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; Setting up Vectror Table (in case exception happens in early boot
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sr @_int_vec_base_lds, [AUX_INTR_VEC_BASE]
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; Disable I-cache/D-cache if kernel so configured
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lr r5, [ARC_REG_IC_BCR]
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breq r5, 0, 1f ; I$ doesn't exist
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lr r5, [ARC_REG_IC_CTRL]
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#ifdef CONFIG_ARC_HAS_ICACHE
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bclr r5, r5, 0 ; 0 - Enable, 1 is Disable
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#else
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bset r5, r5, 0 ; I$ exists, but is not used
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#endif
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sr r5, [ARC_REG_IC_CTRL]
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1:
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lr r5, [ARC_REG_DC_BCR]
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breq r5, 0, 1f ; D$ doesn't exist
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lr r5, [ARC_REG_DC_CTRL]
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bclr r5, r5, 6 ; Invalidate (discard w/o wback)
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#ifdef CONFIG_ARC_HAS_DCACHE
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bclr r5, r5, 0 ; Enable (+Inv)
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#else
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bset r5, r5, 0 ; Disable (+Inv)
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#endif
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sr r5, [ARC_REG_DC_CTRL]
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1:
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#ifdef CONFIG_ISA_ARCV2
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; Unaligned access is disabled at reset, so re-enable early as
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; gcc 7.3.1 (ARC GNU 2018.03) onwards generates unaligned access
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; by default
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lr r5, [status32]
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#ifdef CONFIG_ARC_USE_UNALIGNED_MEM_ACCESS
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bset r5, r5, STATUS_AD_BIT
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#else
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; Although disabled at reset, bootloader might have enabled it
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bclr r5, r5, STATUS_AD_BIT
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#endif
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kflag r5
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#endif
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; Config DSP_CTRL properly, so kernel may use integer multiply,
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; multiply-accumulate, and divide operations
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DSP_EARLY_INIT
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.endm
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.section .init.text, "ax",@progbits
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;----------------------------------------------------------------
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; Default Reset Handler (jumped into from Reset vector)
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; - Don't clobber r0,r1,r2 as they might have u-boot provided args
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; - Platforms can override this weak version if needed
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;----------------------------------------------------------------
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WEAK(res_service)
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j stext
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END(res_service)
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;----------------------------------------------------------------
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; Kernel Entry point
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;----------------------------------------------------------------
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ENTRY(stext)
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CPU_EARLY_SETUP
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#ifdef CONFIG_SMP
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GET_CPU_ID r5
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cmp r5, 0
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mov.nz r0, r5
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bz .Lmaster_proceed
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; Non-Masters wait for Master to boot enough and bring them up
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; when they resume, tail-call to entry point
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mov blink, @first_lines_of_secondary
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j arc_platform_smp_wait_to_boot
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.Lmaster_proceed:
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#endif
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; Clear BSS before updating any globals
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; XXX: use ZOL here
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mov r5, __bss_start
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sub r6, __bss_stop, r5
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lsr.f lp_count, r6, 2
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lpnz 1f
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st.ab 0, [r5, 4]
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1:
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; Uboot - kernel ABI
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; r0 = [0] No uboot interaction, [1] cmdline in r2, [2] DTB in r2
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; r1 = magic number (always zero as of now)
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; r2 = pointer to uboot provided cmdline or external DTB in mem
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; These are handled later in handle_uboot_args()
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st r0, [@uboot_tag]
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st r1, [@uboot_magic]
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st r2, [@uboot_arg]
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; setup "current" tsk and optionally cache it in dedicated r25
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mov r9, @init_task
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SET_CURR_TASK_ON_CPU r9, r0 ; r9 = tsk, r0 = scratch
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; setup stack (fp, sp)
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mov fp, 0
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; tsk->thread_info is really a PAGE, whose bottom hoists stack
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GET_TSK_STACK_BASE r9, sp ; r9 = tsk, sp = stack base(output)
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j start_kernel ; "C" entry point
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END(stext)
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#ifdef CONFIG_SMP
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;----------------------------------------------------------------
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; First lines of code run by secondary before jumping to 'C'
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;----------------------------------------------------------------
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.section .text, "ax",@progbits
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ENTRY(first_lines_of_secondary)
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; setup per-cpu idle task as "current" on this CPU
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ld r0, [@secondary_idle_tsk]
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SET_CURR_TASK_ON_CPU r0, r1
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; setup stack (fp, sp)
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mov fp, 0
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; set it's stack base to tsk->thread_info bottom
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GET_TSK_STACK_BASE r0, sp
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j start_kernel_secondary
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END(first_lines_of_secondary)
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#endif
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