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b844489ec0
Commit 43569ee374 ("Fix objtool: missing int3 after ret warning")
addressed replacing all `ret`s in x86 asm code to a macro in the
Linux kernel in order to enable SLS. That was done by copying the
upstream macro definitions and fixed objtool complaints.
Since then, several more mitigations were introduced, including
Rethunk. It requires to have a jump to one of the thunks in order
to work, so the RET macro was changed again. And, as ZFS code
didn't use the mainline defition, but copied it, this is currently
missing.
Objtool reminds about it time to time (Clang 16, CONFIG_RETHUNK=y):
fs/zfs/lua/zlua.o: warning: objtool: setjmp+0x25: 'naked' return
found in RETHUNK build
fs/zfs/lua/zlua.o: warning: objtool: longjmp+0x27: 'naked' return
found in RETHUNK build
Do it the following way:
* if we're building under Linux, unconditionally include
<linux/linkage.h> in the related files. It is available in x86
sources since even pre-2.6 times, so doesn't need any conftests;
* then, if RET macro is available, it will be used directly, so that
we will always have the version actual to the kernel we build;
* if there's no such macro, we define it as a simple `ret`, as it
was on pre-SLS times.
This ensures we always have the up-to-date definition with no need
to update it manually, and at the same time is safe for the whole
variety of kernels ZFS module supports.
Then, there's a couple more "naked" rets left in the code, they're
just defined as:
.byte 0xf3,0xc3
In fact, this is just:
rep ret
`rep ret` instead of just `ret` seems to mitigate performance issues
on some old AMD processors and most likely makes no sense as of
today.
Anyways, address those rets, so that they will be protected with
Rethunk and SLS. Include <sys/asm_linkage.h> here which now always
has RET definition and replace those constructs with just RET.
This wipes the last couple of places with unpatched rets objtool's
been complaining about.
Reviewed-by: Attila Fülöp <attila@fueloep.org>
Reviewed-by: Tino Reichardt <milky-zfs@mcmilk.de>
Reviewed-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Alexander Lobakin <alobakin@pm.me>
Closes #14035
177 lines
3.8 KiB
C
177 lines
3.8 KiB
C
/*
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* CDDL HEADER START
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*
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* The contents of this file are subject to the terms of the
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* Common Development and Distribution License (the "License").
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* You may not use this file except in compliance with the License.
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*
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* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
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* or https://opensource.org/licenses/CDDL-1.0.
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* See the License for the specific language governing permissions
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* and limitations under the License.
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*
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* When distributing Covered Code, include this CDDL HEADER in each
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* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
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* If applicable, add the following below this CDDL HEADER, with the
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* fields enclosed by brackets "[]" replaced with your own identifying
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* information: Portions Copyright [yyyy] [name of copyright owner]
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*
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* CDDL HEADER END
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*/
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/*
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* Copyright 2008 Sun Microsystems, Inc. All rights reserved.
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* Use is subject to license terms.
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*/
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#ifndef _IA32_SYS_ASM_LINKAGE_H
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#define _IA32_SYS_ASM_LINKAGE_H
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#include <sys/stack.h>
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#include <sys/trap.h>
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#if defined(_KERNEL) && defined(__linux__)
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#include <linux/linkage.h>
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#endif
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#ifndef RET
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#define RET ret
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#endif
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#ifdef __cplusplus
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extern "C" {
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#endif
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#ifdef _ASM /* The remainder of this file is only for assembly files */
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/*
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* make annoying differences in assembler syntax go away
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*/
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/*
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* D16 and A16 are used to insert instructions prefixes; the
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* macros help the assembler code be slightly more portable.
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*/
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#if !defined(__GNUC_AS__)
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/*
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* /usr/ccs/bin/as prefixes are parsed as separate instructions
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*/
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#define D16 data16;
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#define A16 addr16;
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/*
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* (There are some weird constructs in constant expressions)
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*/
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#define _CONST(const) [const]
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#define _BITNOT(const) -1!_CONST(const)
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#define _MUL(a, b) _CONST(a \* b)
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#else
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/*
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* Why not use the 'data16' and 'addr16' prefixes .. well, the
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* assembler doesn't quite believe in real mode, and thus argues with
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* us about what we're trying to do.
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*/
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#define D16 .byte 0x66;
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#define A16 .byte 0x67;
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#define _CONST(const) (const)
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#define _BITNOT(const) ~_CONST(const)
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#define _MUL(a, b) _CONST(a * b)
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#endif
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/*
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* C pointers are different sizes between i386 and amd64.
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* These constants can be used to compute offsets into pointer arrays.
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*/
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#if defined(__amd64)
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#define CLONGSHIFT 3
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#define CLONGSIZE 8
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#define CLONGMASK 7
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#elif defined(__i386)
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#define CLONGSHIFT 2
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#define CLONGSIZE 4
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#define CLONGMASK 3
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#endif
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/*
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* Since we know we're either ILP32 or LP64 ..
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*/
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#define CPTRSHIFT CLONGSHIFT
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#define CPTRSIZE CLONGSIZE
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#define CPTRMASK CLONGMASK
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#if CPTRSIZE != (1 << CPTRSHIFT) || CLONGSIZE != (1 << CLONGSHIFT)
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#error "inconsistent shift constants"
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#endif
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#if CPTRMASK != (CPTRSIZE - 1) || CLONGMASK != (CLONGSIZE - 1)
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#error "inconsistent mask constants"
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#endif
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#define ASM_ENTRY_ALIGN 16
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/*
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* SSE register alignment and save areas
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*/
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#define XMM_SIZE 16
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#define XMM_ALIGN 16
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/*
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* ENTRY provides the standard procedure entry code and an easy way to
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* insert the calls to mcount for profiling. ENTRY_NP is identical, but
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* never calls mcount.
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*/
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#undef ENTRY
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#define ENTRY(x) \
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.text; \
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.align ASM_ENTRY_ALIGN; \
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.globl x; \
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.type x, @function; \
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x: MCOUNT(x)
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#define ENTRY_NP(x) \
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.text; \
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.align ASM_ENTRY_ALIGN; \
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.globl x; \
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.type x, @function; \
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x:
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/*
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* ENTRY2 is identical to ENTRY but provides two labels for the entry point.
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*/
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#define ENTRY2(x, y) \
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.text; \
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.align ASM_ENTRY_ALIGN; \
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.globl x, y; \
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.type x, @function; \
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.type y, @function; \
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x:; \
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y: MCOUNT(x)
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#define ENTRY_NP2(x, y) \
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.text; \
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.align ASM_ENTRY_ALIGN; \
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.globl x, y; \
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.type x, @function; \
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.type y, @function; \
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x:; \
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y:
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/*
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* SET_SIZE trails a function and set the size for the ELF symbol table.
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*/
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#define SET_SIZE(x) \
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.size x, [.-x]
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#endif /* _ASM */
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#ifdef __cplusplus
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}
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#endif
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#endif /* _IA32_SYS_ASM_LINKAGE_H */
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