Unverified Commit 800149a7 authored by Vincent Chen's avatar Vincent Chen Committed by Palmer Dabbelt
Browse files

riscv: sifive: Apply errata "cip-453" patch 



Add sign extension to the $badaddr before addressing the instruction page
fault and instruction access fault to workaround the issue "cip-453".

To avoid affecting the existing code sequence, this patch will creates two
trampolines to add sign extension to the $badaddr. By the "alternative"
mechanism, these two trampolines will replace the original exception
handler of instruction page fault and instruction access fault in the
excp_vect_table. In this case, only the specific SiFive CPU core jumps to
the do_page_fault and do_trap_insn_fault through these two trampolines.
Other CPUs are not affected.

Signed-off-by: default avatarVincent Chen <vincent.chen@sifive.com>
Signed-off-by: default avatarPalmer Dabbelt <palmerdabbelt@google.com>
parent 1a0e5dbd

arch/riscv/Kconfig.erratas

+11 −0
Original line number Diff line number Diff line
@@ -19,4 +19,15 @@ config ERRATA_SIFIVE 


	  Otherwise, please say "N" here to avoid unnecessary overhead.



config ERRATA_SIFIVE_CIP_453

	bool "Apply SiFive errata CIP-453"

	depends on ERRATA_SIFIVE

	default y

	help

	  This will apply the SiFive CIP-453 errata to add sign extension

	  to the $badaddr when exception type is instruction page fault

	  and instruction access fault.



	  If you don't know what to do here, say "Y".



endmenu

arch/riscv/errata/sifive/Makefile

+1 −0
Original line number Diff line number Diff line 
obj-y += errata_cip_453.o

obj-y += errata.o

arch/riscv/errata/sifive/errata.c

+20 −0
Original line number Diff line number Diff line
@@ -16,6 +16,26 @@ struct errata_info_t { 
	bool (*check_func)(unsigned long  arch_id, unsigned long impid);

};



static bool errata_cip_453_check_func(unsigned long  arch_id, unsigned long impid)

{

	/*

	 * Affected cores:

	 * Architecture ID: 0x8000000000000007

	 * Implement ID: 0x20181004 <= impid <= 0x20191105

	 */

	if (arch_id != 0x8000000000000007 ||

	    (impid < 0x20181004 || impid > 0x20191105))

		return false;

	return true;

}



static struct errata_info_t errata_list[ERRATA_SIFIVE_NUMBER] = {

	{

		.name = "cip-453",

		.check_func = errata_cip_453_check_func

	},

};



static u32 __init sifive_errata_probe(unsigned long archid, unsigned long impid)

{

	int idx;

arch/riscv/errata/sifive/errata_cip_453.S

0 → 100644
+38 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0-only */

/*

 * Copyright (C) 2021 SiFive

 */



#include <linux/linkage.h>

#include <asm/asm.h>

#include <asm/asm-offsets.h>

#include <asm/alternative.h>



.macro ADD_SIGN_EXT pt_reg badaddr tmp_reg

	REG_L \badaddr, PT_BADADDR(\pt_reg)

	li \tmp_reg,1

	slli \tmp_reg,\tmp_reg,0x26

	and \tmp_reg,\tmp_reg,\badaddr

	beqz \tmp_reg, 1f

	li \tmp_reg,-1

	slli \tmp_reg,\tmp_reg,0x27

	or \badaddr,\tmp_reg,\badaddr

	REG_S \badaddr, PT_BADADDR(\pt_reg)

1:

.endm



ENTRY(sifive_cip_453_page_fault_trp)

	ADD_SIGN_EXT a0, t0, t1

#ifdef CONFIG_MMU

	la t0, do_page_fault

#else

	la t0, do_trap_unknown

#endif

	jr t0

END(sifive_cip_453_page_fault_trp)



ENTRY(sifive_cip_453_insn_fault_trp)

	ADD_SIGN_EXT a0, t0, t1

	la t0, do_trap_insn_fault

	jr t0

END(sifive_cip_453_insn_fault_trp)

arch/riscv/include/asm/errata_list.h

+20 −1
Original line number Diff line number Diff line
@@ -5,8 +5,27 @@ 
#ifndef ASM_ERRATA_LIST_H

#define ASM_ERRATA_LIST_H



#include <asm/alternative.h>

#include <asm/vendorid_list.h>



#ifdef CONFIG_ERRATA_SIFIVE

#define	ERRATA_SIFIVE_NUMBER 0

#define	ERRATA_SIFIVE_CIP_453 0

#define	ERRATA_SIFIVE_NUMBER 1

#endif



#ifdef __ASSEMBLY__



#define ALT_INSN_FAULT(x)						\

ALTERNATIVE(__stringify(RISCV_PTR do_trap_insn_fault),			\

	    __stringify(RISCV_PTR sifive_cip_453_insn_fault_trp),	\

	    SIFIVE_VENDOR_ID, ERRATA_SIFIVE_CIP_453,			\

	    CONFIG_ERRATA_SIFIVE_CIP_453)



#define ALT_PAGE_FAULT(x)						\

ALTERNATIVE(__stringify(RISCV_PTR do_page_fault),			\

	    __stringify(RISCV_PTR sifive_cip_453_page_fault_trp),	\

	    SIFIVE_VENDOR_ID, ERRATA_SIFIVE_CIP_453,			\

	    CONFIG_ERRATA_SIFIVE_CIP_453)

#endif /* __ASSEMBLY__ */



#endif