Messages in this thread | | | Date | Tue, 23 Apr 2019 15:18:23 -0500 | From | Josh Poimboeuf <> | Subject | Re: [RFC 2/6] objtool: arm64: Add required implementation for supporting the aarch64 architecture in objtool. |
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On Tue, Apr 09, 2019 at 02:52:39PM +0100, Raphael Gault wrote: > Provide implementation for the arch-dependent functions that are called by the main check > function of objtool. > The ORC unwinder is not yet supported by the arm64 architecture so we only provide a dummy > interface for now. > The decoding of the instruction is split into classes and subclasses as described into > the Instruction Encoding in the ArmV8.5 Architecture Reference Manual.
Where did the code for the decoder come from? Was it written from scratch?
> diff --git a/tools/objtool/arch/arm64/include/arch_special.h b/tools/objtool/arch/arm64/include/arch_special.h > new file mode 100644 > index 000000000000..54bcce4c58c0 > --- /dev/null > +++ b/tools/objtool/arch/arm64/include/arch_special.h > @@ -0,0 +1,44 @@ > +/* > + * 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. > + * > + * You should have received a copy of the GNU General Public License > + * along with this program; if not, see <http://www.gnu.org/licenses/>. > + */ > +
Needs a header guard.
> +#define EX_ENTRY_SIZE 8 > +#define EX_ORIG_OFFSET 0 > +#define EX_NEW_OFFSET 4 > + > +#define JUMP_ENTRY_SIZE 16 > +#define JUMP_ORIG_OFFSET 0 > +#define JUMP_NEW_OFFSET 4 > + > +#define ALT_ENTRY_SIZE 12 > +#define ALT_ORIG_OFFSET 0 > +#define ALT_NEW_OFFSET 4 > +#define ALT_FEATURE_OFFSET 8 > +#define ALT_ORIG_LEN_OFFSET 10 > +#define ALT_NEW_LEN_OFFSET 11 > + > +/* > + * On arm64 the .altinstr_replacement is not always marked > + * as containing executable instruction. But we still want > + * to process it so we ignore the SHF_EXEC flag > + */ > +#define IGNORE_SHF_EXEC_FLAG 1 > + > +/* > + * The jump table detection is not the same on arm64 so for > + * now we just detect if it is a dynamic jump (br <Xn> insn) > + */ > +#define JUMP_DYNAMIC_IS_SWITCH_TABLE 1
Same as for x86, these flags should be added in the same patch which uses them.
> + > +#define X86_FEATURE_POPCNT (4*32+23) > diff --git a/tools/objtool/arch/arm64/include/asm/orc_types.h b/tools/objtool/arch/arm64/include/asm/orc_types.h > new file mode 100644 > index 000000000000..46f516dd80ce > --- /dev/null > +++ b/tools/objtool/arch/arm64/include/asm/orc_types.h > @@ -0,0 +1,109 @@ > +/* > + * Copyright (C) 2017 Josh Poimboeuf <jpoimboe@redhat.com> > + * > + * 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. > + * > + * You should have received a copy of the GNU General Public License > + * along with this program; if not, see <http://www.gnu.org/licenses/>. > + */ > + > +#ifndef _ORC_TYPES_H > +#define _ORC_TYPES_H > + > +#include <linux/types.h> > +#include <linux/compiler.h> > + > +/* > + * The ORC_REG_* registers are base registers which are used to find other > + * registers on the stack. > + * > + * ORC_REG_PREV_SP, also known as DWARF Call Frame Address (CFA), is the > + * address of the previous frame: the caller's SP before it called the current > + * function. > + * > + * ORC_REG_UNDEFINED means the corresponding register's value didn't change in > + * the current frame. > + * > + * The most commonly used base registers are SP and BP -- which the previous SP > + * is usually based on -- and PREV_SP and UNDEFINED -- which the previous BP is > + * usually based on. > + * > + * The rest of the base registers are needed for special cases like entry code > + * and GCC realigned stacks. > + */ > +#define ORC_REG_UNDEFINED 0 > +#define ORC_REG_PREV_SP 1 > +#define ORC_REG_DX 2 > +#define ORC_REG_DI 3 > +#define ORC_REG_BP 4 > +#define ORC_REG_SP 5 > +#define ORC_REG_R10 6 > +#define ORC_REG_R13 7 > +#define ORC_REG_BP_INDIRECT 8 > +#define ORC_REG_SP_INDIRECT 9 > +#define ORC_REG_MAX 15 > + > +/* > + * ORC_TYPE_CALL: Indicates that sp_reg+sp_offset resolves to PREV_SP (the > + * caller's SP right before it made the call). Used for all callable > + * functions, i.e. all C code and all callable asm functions. > + * > + * ORC_TYPE_REGS: Used in entry code to indicate that sp_reg+sp_offset points > + * to a fully populated pt_regs from a syscall, interrupt, or exception. > + * > + * ORC_TYPE_REGS_IRET: Used in entry code to indicate that sp_reg+sp_offset > + * points to the iret return frame. > + * > + * The UNWIND_HINT macros are used only for the unwind_hint struct. They > + * aren't used in struct orc_entry due to size and complexity constraints. > + * Objtool converts them to real types when it converts the hints to orc > + * entries. > + */ > +#define ORC_TYPE_CALL 0 > +#define ORC_TYPE_REGS 1 > +#define ORC_TYPE_REGS_IRET 2 > +#define UNWIND_HINT_TYPE_SAVE 3 > +#define UNWIND_HINT_TYPE_RESTORE 4 > + > +#ifndef __ASSEMBLY__ > +/* > + * This struct is more or less a vastly simplified version of the DWARF Call > + * Frame Information standard. It contains only the necessary parts of DWARF > + * CFI, simplified for ease of access by the in-kernel unwinder. It tells the > + * unwinder how to find the previous SP and BP (and sometimes entry regs) on > + * the stack for a given code address. Each instance of the struct corresponds > + * to one or more code locations. > + */ > +struct orc_entry { > + s16 sp_offset; > + s16 bp_offset; > + unsigned sp_reg:4; > + unsigned bp_reg:4; > + unsigned type:2; > + unsigned end:1; > +} __packed; > + > +/* > + * This struct is used by asm and inline asm code to manually annotate the > + * location of registers on the stack for the ORC unwinder. > + * > + * Type can be either ORC_TYPE_* or UNWIND_HINT_TYPE_*. > + */ > +struct unwind_hint { > + u32 ip; > + s16 sp_offset; > + u8 sp_reg; > + u8 type; > + u8 end; > +}; > +#endif /* __ASSEMBLY__ */ > + > +#endif /* _ORC_TYPES_H */
It seems odd to have the above header file in arm64 code, since it doesn't implement ORC. Is it really needed?
-- Josh
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