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(firewall.ctxuk.citrix.com. [46.33.159.2]) by mx.google.com with ESMTPSA id p5sm18995284eeg.5.2013.08.08.05.56.58 for (version=TLSv1.2 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Thu, 08 Aug 2013 05:56:59 -0700 (PDT) From: Julien Grall To: xen-devel@lists.xen.org Cc: stefano.stabellini@eu.citrix.com, ian.campbell@citrix.com, patches@linaro.org, tim@xen.org, Julien Grall Subject: [PATCH v5 1/2] xen/arm: Start to implement an ARM decoder instruction Date: Thu, 8 Aug 2013 13:56:50 +0100 Message-Id: <1375966611-16942-2-git-send-email-julien.grall@linaro.org> X-Mailer: git-send-email 1.7.10.4 In-Reply-To: <1375966611-16942-1-git-send-email-julien.grall@linaro.org> References: <1375966611-16942-1-git-send-email-julien.grall@linaro.org> X-Removed-Original-Auth: Dkim didn't pass. X-Original-Sender: julien.grall@linaro.org X-Original-Authentication-Results: mx.google.com; spf=neutral (google.com: 209.85.220.174 is neither permitted nor denied by best guess record for domain of patch+caf_=patchwork-forward=linaro.org@linaro.org) smtp.mail=patch+caf_=patchwork-forward=linaro.org@linaro.org Precedence: list Mailing-list: list patchwork-forward@linaro.org; contact patchwork-forward+owners@linaro.org List-ID: X-Google-Group-Id: 836684582541 List-Post: , List-Help: , List-Archive: List-Unsubscribe: , Some errata on ARM processor requires to decode the instruction. The decoder will, obviously, decode and fill the ISS fields of the hsr_dabt. For the moment, the decoder only supports: - THUMB2 store instruction - THUMB single load/store instruction Signed-off-by: Julien Grall --- Changes in v5: - Fix typo in commit - Use gdprintk instead of printk - Remove TODOs - Add warning when it's an ARM instruction Changes in v4: - Add warning about the purpose of this function - Add helper to update ISS (register, sign, size) field of DABT - Improve decoding for THUMB 2 store instruction - Only decode thumb instruction if it's a 32-bit guest --- xen/arch/arm/Makefile | 1 + xen/arch/arm/decode.c | 165 +++++++++++++++++++++++++++++++++++++++++++++++++ xen/arch/arm/decode.h | 49 +++++++++++++++ 3 files changed, 215 insertions(+) create mode 100644 xen/arch/arm/decode.c create mode 100644 xen/arch/arm/decode.h diff --git a/xen/arch/arm/Makefile b/xen/arch/arm/Makefile index 6e1208f..003ac84 100644 --- a/xen/arch/arm/Makefile +++ b/xen/arch/arm/Makefile @@ -30,6 +30,7 @@ obj-y += vtimer.o obj-y += vuart.o obj-y += hvm.o obj-y += device.o +obj-y += decode.o #obj-bin-y += ....o diff --git a/xen/arch/arm/decode.c b/xen/arch/arm/decode.c new file mode 100644 index 0000000..abe9f26 --- /dev/null +++ b/xen/arch/arm/decode.c @@ -0,0 +1,165 @@ +/* + * xen/arch/arm/decode.c + * + * Instruction decoder + * + * Julien Grall + * Copyright (C) 2013 Linaro Limited. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + +#include +#include +#include +#include +#include + +#include "decode.h" + +static void update_dabt(struct hsr_dabt *dabt, int reg, + uint8_t size, bool_t sign) +{ + dabt->reg = reg; + dabt->size = size; + dabt->sign = sign; +} + +static int decode_thumb2(register_t pc, struct hsr_dabt *dabt, uint16_t hw1) +{ + uint16_t hw2; + int rc; + uint16_t rt; + + rc = raw_copy_from_guest(&hw2, (void *__user)(pc + 2), sizeof (hw2)); + if ( rc ) + return rc; + + rt = (hw2 >> 12) & 0x7; + + switch ( (hw1 >> 9) & 0xf ) + { + case 12: + { + bool_t sign = !!(hw1 & (1 << 8)); + bool_t load = !!(hw1 & (1 << 4)); + + if ( (hw1 & 0x0110) == 0x0100 ) + /* NEON instruction */ + goto bad_thumb2; + + if ( (hw1 & 0x0070) == 0x0070 ) + /* Undefined opcodes */ + goto bad_thumb2; + + /* Store/Load single data item */ + if ( rt == 15 ) + /* XXX: Rt == 15 is only invalid for store instruction */ + goto bad_thumb2; + + if ( !load && sign ) + /* Store instruction doesn't support sign extension */ + goto bad_thumb2; + + update_dabt(dabt, rt, (hw1 >> 5) & 3, sign); + + break; + } + default: + goto bad_thumb2; + } + + return 0; + +bad_thumb2: + gdprintk(XENLOG_ERR, "unhandled THUMB2 instruction 0x%x%x\n", hw1, hw2); + + return 1; +} + +static int decode_thumb(register_t pc, struct hsr_dabt *dabt) +{ + uint16_t instr; + int rc; + + rc = raw_copy_from_guest(&instr, (void * __user)pc, sizeof (instr)); + if ( rc ) + return rc; + + switch ( instr >> 12 ) + { + case 5: + { + /* Load/Store register */ + uint16_t opB = (instr >> 9) & 0x7; + int reg = instr & 7; + + switch ( opB & 0x3 ) + { + case 0: /* Non-signed word */ + update_dabt(dabt, reg, 2, 0); + break; + case 1: /* Non-signed halfword */ + update_dabt(dabt, reg, 1, 0); + break; + case 2: /* Non-signed byte */ + update_dabt(dabt, reg, 0, 0); + break; + case 3: /* Signed byte */ + update_dabt(dabt, reg, 0, 1); + break; + } + + break; + } + case 6: + /* Load/Store word immediate offset */ + update_dabt(dabt, instr & 7, 2, 0); + break; + case 7: + /* Load/Store byte immediate offset */ + update_dabt(dabt, instr & 7, 0, 0); + break; + case 8: + /* Load/Store halfword immediate offset */ + update_dabt(dabt, instr & 7, 1, 0); + break; + case 9: + /* Load/Store word sp offset */ + update_dabt(dabt, (instr >> 8) & 7, 2, 0); + break; + case 14: + if ( instr & (1 << 11) ) + return decode_thumb2(pc, dabt, instr); + goto bad_thumb; + case 15: + return decode_thumb2(pc, dabt, instr); + default: + goto bad_thumb; + } + + return 0; + +bad_thumb: + gdprintk(XENLOG_ERR, "unhandled THUMB instruction 0x%x\n", instr); + return 1; +} + +int decode_instruction(const struct cpu_user_regs *regs, struct hsr_dabt *dabt) +{ + if ( is_pv32_domain(current->domain) && regs->cpsr & PSR_THUMB ) + return decode_thumb(regs->pc, dabt); + + /* TODO: Handle ARM instruction */ + gdprintk(XENLOG_ERR, "unhandled ARM instruction\n"); + + return 1; +} diff --git a/xen/arch/arm/decode.h b/xen/arch/arm/decode.h new file mode 100644 index 0000000..4613763 --- /dev/null +++ b/xen/arch/arm/decode.h @@ -0,0 +1,49 @@ +/* + * xen/arch/arm/decode.h + * + * Instruction decoder + * + * Julien Grall + * Copyright (C) 2013 Linaro Limited. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + +#ifndef __ARCH_ARM_DECODE_H_ +#define __ARCH_ARM_DECODE_H_ + +#include +#include + +/** + * Decode an instruction from pc + * /!\ This function is not intended to fully decode an instruction. It + * considers that the instruction is valid. + * + * This function will get: + * - The transfer register + * - Sign bit + * - Size + */ + +int decode_instruction(const struct cpu_user_regs *regs, + struct hsr_dabt *dabt); + +#endif /* __ARCH_ARM_DECODE_H_ */ + +/* + * Local variables: + * mode: C + * c-file-style: "BSD" + * c-basic-offset: 4 + * indent-tabs-mode: nil + * End: + */