commit 134ab5bd1883312d7a4b3033b05c6b5a1bb8889b upstream.
Instead of writing complete alternatives, simply provide a list of all
the retpoline thunk calls. Then the kernel is free to do with them as
it pleases. Simpler code all-round.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Borislav Petkov <bp@suse.de>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Tested-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/r/20211026120309.850007165@infradead.org
[cascardo: fixed conflict because of missing
8b946cc38e063f0f7bb67789478c38f6d7d457c9]
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 7a53f408902d913cd541b4f8ad7dbcd4961f5b82 ]
Since not all compilers have a function attribute to disable KCOV
instrumentation, objtool can rewrite KCOV instrumentation in noinstr
functions as per commit:
f56dae88a81f ("objtool: Handle __sanitize_cov*() tail calls")
However, this has subtle interaction with the SLS validation from
commit:
1cc1e4c8aab4 ("objtool: Add straight-line-speculation validation")
In that when a tail-call instrucion is replaced with a RET an
additional INT3 instruction is also written, but is not represented in
the decoded instruction stream.
This then leads to false positive missing INT3 objtool warnings in
noinstr code.
Instead of adding additional struct instruction objects, mark the RET
instruction with retpoline_safe to suppress the warning (since we know
there really is an INT3).
Fixes: 1cc1e4c8aab4 ("objtool: Add straight-line-speculation validation")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20220323230712.GA8939@worktop.programming.kicks-ass.net
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 1cc1e4c8aab4213bd4e6353dec2620476a233d6d ]
Teach objtool to validate the straight-line-speculation constraints:
- speculation trap after indirect calls
- speculation trap after RET
Notable: when an instruction is annotated RETPOLINE_SAFE, indicating
speculation isn't a problem, also don't care about sls for that
instruction.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20211204134908.023037659@infradead.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 9af9dcf11bda3e2c0e24c1acaacb8685ad974e93 ]
The asm_cpu_bringup_and_idle() function is required to push the return
value on the stack in order to make ORC happy, but the only reason
objtool doesn't complain is because of a happy accident.
The thing is that asm_cpu_bringup_and_idle() doesn't return, so
validate_branch() never terminates and falls through to the next
function, which in the normal case is the hypercall_page. And that, as
it happens, is 4095 NOPs and a RET.
Make asm_cpu_bringup_and_idle() terminate on it's own, by making the
function it calls as a dead-end. This way we no longer rely on what
code happens to come after.
Fixes: c3881eb58d ("x86/xen: Make the secondary CPU idle tasks reliable")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lore.kernel.org/r/20210624095147.693801717@infradead.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
Pull objtool updates from Ingo Molnar:
- Standardize the crypto asm code so that it looks like compiler-
generated code to objtool - so that it can understand it. This
enables unwinding from crypto asm code - and also fixes the last
known remaining objtool warnings for LTO and more.
- x86 decoder fixes: clean up and fix the decoder, and also extend it a
bit
- Misc fixes and cleanups
* tag 'objtool-core-2021-04-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits)
x86/crypto: Enable objtool in crypto code
x86/crypto/sha512-ssse3: Standardize stack alignment prologue
x86/crypto/sha512-avx2: Standardize stack alignment prologue
x86/crypto/sha512-avx: Standardize stack alignment prologue
x86/crypto/sha256-avx2: Standardize stack alignment prologue
x86/crypto/sha1_avx2: Standardize stack alignment prologue
x86/crypto/sha_ni: Standardize stack alignment prologue
x86/crypto/crc32c-pcl-intel: Standardize jump table
x86/crypto/camellia-aesni-avx2: Unconditionally allocate stack buffer
x86/crypto/aesni-intel_avx: Standardize stack alignment prologue
x86/crypto/aesni-intel_avx: Fix register usage comments
x86/crypto/aesni-intel_avx: Remove unused macros
objtool: Support asm jump tables
objtool: Parse options from OBJTOOL_ARGS
objtool: Collate parse_options() users
objtool: Add --backup
objtool,x86: More ModRM sugar
objtool,x86: Rewrite ADD/SUB/AND
objtool,x86: Support %riz encodings
objtool,x86: Simplify register decode
...
Provide infrastructure for architectures to rewrite/augment compiler
generated retpoline calls. Similar to what we do for static_call()s,
keep track of the instructions that are retpoline calls.
Use the same list_head, since a retpoline call cannot also be a
static_call.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/20210326151300.130805730@infradead.org
Instead of manually calling elf_rebuild_reloc_section() on sections
we've called elf_add_reloc() on, have elf_write() DTRT.
This makes it easier to add random relocations in places without
carefully tracking when we're done and need to flush what section.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/20210326151259.754213408@infradead.org
Due to:
c9c324dc22 ("objtool: Support stack layout changes in alternatives")
it is now possible to simplify the retpolines.
Currently our retpolines consist of 2 symbols:
- __x86_indirect_thunk_\reg: the compiler target
- __x86_retpoline_\reg: the actual retpoline.
Both are consecutive in code and aligned such that for any one register
they both live in the same cacheline:
0000000000000000 <__x86_indirect_thunk_rax>:
0: ff e0 jmpq *%rax
2: 90 nop
3: 90 nop
4: 90 nop
0000000000000005 <__x86_retpoline_rax>:
5: e8 07 00 00 00 callq 11 <__x86_retpoline_rax+0xc>
a: f3 90 pause
c: 0f ae e8 lfence
f: eb f9 jmp a <__x86_retpoline_rax+0x5>
11: 48 89 04 24 mov %rax,(%rsp)
15: c3 retq
16: 66 2e 0f 1f 84 00 00 00 00 00 nopw %cs:0x0(%rax,%rax,1)
The thunk is an alternative_2, where one option is a JMP to the
retpoline. This was done so that objtool didn't need to deal with
alternatives with stack ops. But that problem has been solved, so now
it is possible to fold the entire retpoline into the alternative to
simplify and consolidate unused bytes:
0000000000000000 <__x86_indirect_thunk_rax>:
0: ff e0 jmpq *%rax
2: 90 nop
3: 90 nop
4: 90 nop
5: 90 nop
6: 90 nop
7: 90 nop
8: 90 nop
9: 90 nop
a: 90 nop
b: 90 nop
c: 90 nop
d: 90 nop
e: 90 nop
f: 90 nop
10: 90 nop
11: 66 66 2e 0f 1f 84 00 00 00 00 00 data16 nopw %cs:0x0(%rax,%rax,1)
1c: 0f 1f 40 00 nopl 0x0(%rax)
Notice that since the longest alternative sequence is now:
0: e8 07 00 00 00 callq c <.altinstr_replacement+0xc>
5: f3 90 pause
7: 0f ae e8 lfence
a: eb f9 jmp 5 <.altinstr_replacement+0x5>
c: 48 89 04 24 mov %rax,(%rsp)
10: c3 retq
17 bytes, we have 15 bytes NOP at the end of our 32 byte slot. (IOW, if
we can shrink the retpoline by 1 byte we can pack it more densely).
[ bp: Massage commit message. ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20210326151259.506071949@infradead.org
Commit ab234a260b ("x86/pv: Rework arch_local_irq_restore() to not
use popf") replaced "push %reg; popf" with something like: "test
$0x200, %reg; jz 1f; sti; 1:", which breaks the pushf/popf symmetry
that commit ea24213d80 ("objtool: Add UACCESS validation") relies
on.
The result is:
drivers/gpu/drm/amd/amdgpu/si.o: warning: objtool: si_common_hw_init()+0xf36: PUSHF stack exhausted
Meanwhile, commit c9c324dc22 ("objtool: Support stack layout changes
in alternatives") makes that we can actually use stack-ops in
alternatives, which means we can revert 1ff865e343 ("x86,smap: Fix
smap_{save,restore}() alternatives").
That in turn means we can limit the PUSHF/POPF handling of
ea24213d80 to those instructions that are in alternatives.
Fixes: ab234a260b ("x86/pv: Rework arch_local_irq_restore() to not use popf")
Reported-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/YEY4rIbQYa5fnnEp@hirez.programming.kicks-ass.net
rewind_stack_do_exit()
UNWIND_HINT_FUNC
/* Prevent any naive code from trying to unwind to our caller. */
xorl %ebp, %ebp
movq PER_CPU_VAR(cpu_current_top_of_stack), %rax
leaq -PTREGS_SIZE(%rax), %rsp
UNWIND_HINT_REGS
call do_exit
Does unspeakable things to the stack, which objtool currently fails to
detect due to a limitation in instruction decoding. This will be
rectified after which the above will result in:
arch/x86/entry/entry_64.o: warning: objtool: .text+0xab: unsupported stack register modification
Allow the UNWIND_HINT on the next instruction to suppress this, it
will overwrite the state anyway.
Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://lkml.kernel.org/r/20210211173626.918498579@infradead.org
Pull x86 irq entry updates from Thomas Gleixner:
"The irq stack switching was moved out of the ASM entry code in course
of the entry code consolidation. It ended up being suboptimal in
various ways.
This reworks the X86 irq stack handling:
- Make the stack switching inline so the stackpointer manipulation is
not longer at an easy to find place.
- Get rid of the unnecessary indirect call.
- Avoid the double stack switching in interrupt return and reuse the
interrupt stack for softirq handling.
- A objtool fix for CONFIG_FRAME_POINTER=y builds where it got
confused about the stack pointer manipulation"
* tag 'x86-entry-2021-02-24' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
objtool: Fix stack-swizzle for FRAME_POINTER=y
um: Enforce the usage of asm-generic/softirq_stack.h
x86/softirq/64: Inline do_softirq_own_stack()
softirq: Move do_softirq_own_stack() to generic asm header
softirq: Move __ARCH_HAS_DO_SOFTIRQ to Kconfig
x86: Select CONFIG_HAVE_IRQ_EXIT_ON_IRQ_STACK
x86/softirq: Remove indirection in do_softirq_own_stack()
x86/entry: Use run_sysvec_on_irqstack_cond() for XEN upcall
x86/entry: Convert device interrupts to inline stack switching
x86/entry: Convert system vectors to irq stack macro
x86/irq: Provide macro for inlining irq stack switching
x86/apic: Split out spurious handling code
x86/irq/64: Adjust the per CPU irq stack pointer by 8
x86/irq: Sanitize irq stack tracking
x86/entry: Fix instrumentation annotation
Pull more clang LTO updates from Kees Cook:
"Clang LTO x86 enablement.
Full disclosure: while this has _not_ been in linux-next (since it
initially looked like the objtool dependencies weren't going to make
v5.12), it has been under daily build and runtime testing by Sami for
quite some time. These x86 portions have been discussed on lkml, with
Peter, Josh, and others helping nail things down.
The bulk of the changes are to get objtool working happily. The rest
of the x86 enablement is very small.
Summary:
- Generate __mcount_loc in objtool (Peter Zijlstra)
- Support running objtool against vmlinux.o (Sami Tolvanen)
- Clang LTO enablement for x86 (Sami Tolvanen)"
Link: https://lore.kernel.org/lkml/20201013003203.4168817-26-samitolvanen@google.com/
Link: https://lore.kernel.org/lkml/cover.1611263461.git.jpoimboe@redhat.com/
* tag 'clang-lto-v5.12-rc1-part2' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
kbuild: lto: force rebuilds when switching CONFIG_LTO
x86, build: allow LTO to be selected
x86, cpu: disable LTO for cpu.c
x86, vdso: disable LTO only for vDSO
kbuild: lto: postpone objtool
objtool: Split noinstr validation from --vmlinux
x86, build: use objtool mcount
tracing: add support for objtool mcount
objtool: Don't autodetect vmlinux.o
objtool: Fix __mcount_loc generation with Clang's assembler
objtool: Add a pass for generating __mcount_loc
This change adds a --noinstr flag to objtool to allow us to specify
that we're processing vmlinux.o without also enabling noinstr
validation. This is needed to avoid false positives with LTO when we
run objtool on vmlinux.o without CONFIG_DEBUG_ENTRY.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
When objtool generates relocations for the __mcount_loc section, it
tries to reference __fentry__ calls by their section symbol offset.
However, this fails with Clang's integrated assembler as it may not
generate section symbols for every section. This patch looks up a
function symbol instead if the section symbol is missing, similarly
to commit e81e072443 ("objtool: Support Clang non-section symbols
in ORC generation").
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Pull objtool updates from Thomas Gleixner:
- Make objtool work for big-endian cross compiles
- Make stack tracking via stack pointer memory operations match
push/pop semantics to prepare for architectures w/o PUSH/POP
instructions.
- Add support for analyzing alternatives
- Improve retpoline detection and handling
- Improve assembly code coverage on x86
- Provide support for inlined stack switching
* tag 'objtool-core-2021-02-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (33 commits)
objtool: Support stack-swizzle
objtool,x86: Additionally decode: mov %rsp, (%reg)
x86/unwind/orc: Change REG_SP_INDIRECT
x86/power: Support objtool validation in hibernate_asm_64.S
x86/power: Move restore_registers() to top of the file
x86/power: Annotate indirect branches as safe
x86/acpi: Support objtool validation in wakeup_64.S
x86/acpi: Annotate indirect branch as safe
x86/ftrace: Support objtool vmlinux.o validation in ftrace_64.S
x86/xen/pvh: Annotate indirect branch as safe
x86/xen: Support objtool vmlinux.o validation in xen-head.S
x86/xen: Support objtool validation in xen-asm.S
objtool: Add xen_start_kernel() to noreturn list
objtool: Combine UNWIND_HINT_RET_OFFSET and UNWIND_HINT_FUNC
objtool: Add asm version of STACK_FRAME_NON_STANDARD
objtool: Assume only ELF functions do sibling calls
x86/ftrace: Add UNWIND_HINT_FUNC annotation for ftrace_stub
objtool: Support retpoline jump detection for vmlinux.o
objtool: Fix ".cold" section suffix check for newer versions of GCC
objtool: Fix retpoline detection in asm code
...
When objtool encounters the stack-swizzle:
mov %rsp, (%[tos])
mov %[tos], %rsp
...
pop %rsp
Inside a FRAME_POINTER=y build, things go a little screwy because
clearly we're not adjusting the cfa->base. This then results in the
pop %rsp not being detected as a restore of cfa->base so it will turn
into a regular POP and offset the stack, resulting in:
kernel/softirq.o: warning: objtool: do_softirq()+0xdb: return with modified stack frame
Therefore, have "mov %[tos], %rsp" act like a PUSH (it sorta is
anyway) to balance the things out. We're not too concerned with the
actual stack_size for frame-pointer builds, since we don't generate
ORC data for them anyway.
Fixes: aafeb14e9d ("objtool: Support stack-swizzle")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/YC6UC+rc9KKmQrkd@hirez.programming.kicks-ass.net
When exporting static_call_key; with EXPORT_STATIC_CALL*(), the module
can use static_call_update() to change the function called. This is
not desirable in general.
Not exporting static_call_key however also disallows usage of
static_call(), since objtool needs the key to construct the
static_call_site.
Solve this by allowing objtool to create the static_call_site using
the trampoline address when it builds a module and cannot find the
static_call_key symbol. The module loader will then try and map the
trampole back to a key before it constructs the normal sites list.
Doing this requires a trampoline -> key associsation, so add another
magic section that keeps those.
Originally-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20210127231837.ifddpn7rhwdaepiu@treble
Merge in the recent paravirt changes to resolve conflicts caused
by objtool annotations.
Conflicts:
arch/x86/xen/xen-asm.S
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Natively support the stack swizzle pattern:
mov %rsp, (%[tos])
mov %[tos], %rsp
...
pop %rsp
It uses the vals[] array to link the first two stack-ops, and detect
the SP to SP_INDIRECT swizzle.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
The ORC metadata generated for UNWIND_HINT_FUNC isn't actually very
func-like. With certain usages it can cause stack state mismatches
because it doesn't set the return address (CFI_RA).
Also, users of UNWIND_HINT_RET_OFFSET no longer need to set a custom
return stack offset. Instead they just need to specify a func-like
situation, so the current ret_offset code is hacky for no good reason.
Solve both problems by simplifying the RET_OFFSET handling and
converting it into a more useful UNWIND_HINT_FUNC.
If we end up needing the old 'ret_offset' functionality again in the
future, we should be able to support it pretty easily with the addition
of a custom 'sp_offset' in UNWIND_HINT_FUNC.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/db9d1f5d79dddfbb3725ef6d8ec3477ad199948d.1611263462.git.jpoimboe@redhat.com
There's an inconsistency in how sibling calls are detected in
non-function asm code, depending on the scope of the object. If the
target code is external to the object, objtool considers it a sibling
call. If the target code is internal but not a function, objtool
*doesn't* consider it a sibling call.
This can cause some inconsistencies between per-object and vmlinux.o
validation.
Instead, assume only ELF functions can do sibling calls. This generally
matches existing reality, and makes sibling call validation consistent
between vmlinux.o and per-object.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/0e9ab6f3628cc7bf3bde7aa6762d54d7df19ad78.1611263461.git.jpoimboe@redhat.com
Objtool converts direct retpoline jumps to type INSN_JUMP_DYNAMIC, since
that's what they are semantically.
That conversion doesn't work in vmlinux.o validation because the
indirect thunk function is present in the object, so the intra-object
jump check succeeds before the retpoline jump check gets a chance.
Rearrange the checks: check for a retpoline jump before checking for an
intra-object jump.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/4302893513770dde68ddc22a9d6a2a04aca491dd.1611263461.git.jpoimboe@redhat.com
This is basically a revert of commit 644592d328 ("objtool: Fail the
kernel build on fatal errors").
That change turned out to be more trouble than it's worth. Failing the
build is an extreme measure which sometimes gets too much attention and
blocks CI build testing.
These fatal-type warnings aren't yet as rare as we'd hope, due to the
ever-increasing matrix of supported toolchains/plugins and their
fast-changing nature as of late.
Also, there are more people (and bots) looking for objtool warnings than
ever before, so even non-fatal warnings aren't likely to be ignored for
long.
Suggested-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
The ORC unwinder showed a warning [1] which revealed the stack layout
didn't match what was expected. The problem was that paravirt patching
had replaced "CALL *pv_ops.irq.save_fl" with "PUSHF;POP". That changed
the stack layout between the PUSHF and the POP, so unwinding from an
interrupt which occurred between those two instructions would fail.
Part of the agreed upon solution was to rework the custom paravirt
patching code to use alternatives instead, since objtool already knows
how to read alternatives (and converging runtime patching infrastructure
is always a good thing anyway). But the main problem still remains,
which is that runtime patching can change the stack layout.
Making stack layout changes in alternatives was disallowed with commit
7117f16bf4 ("objtool: Fix ORC vs alternatives"), but now that paravirt
is going to be doing it, it needs to be supported.
One way to do so would be to modify the ORC table when the code gets
patched. But ORC is simple -- a good thing! -- and it's best to leave
it alone.
Instead, support stack layout changes by "flattening" all possible stack
states (CFI) from parallel alternative code streams into a single set of
linear states. The only necessary limitation is that CFI conflicts are
disallowed at all possible instruction boundaries.
For example, this scenario is allowed:
Alt1 Alt2 Alt3
0x00 CALL *pv_ops.save_fl CALL xen_save_fl PUSHF
0x01 POP %RAX
0x02 NOP
...
0x05 NOP
...
0x07 <insn>
The unwind information for offset-0x00 is identical for all 3
alternatives. Similarly offset-0x05 and higher also are identical (and
the same as 0x00). However offset-0x01 has deviating CFI, but that is
only relevant for Alt3, neither of the other alternative instruction
streams will ever hit that offset.
This scenario is NOT allowed:
Alt1 Alt2
0x00 CALL *pv_ops.save_fl PUSHF
0x01 NOP6
...
0x07 NOP POP %RAX
The problem here is that offset-0x7, which is an instruction boundary in
both possible instruction patch streams, has two conflicting stack
layouts.
[ The above examples were stolen from Peter Zijlstra. ]
The new flattened CFI array is used both for the detection of conflicts
(like the second example above) and the generation of linear ORC
entries.
BTW, another benefit of these changes is that, thanks to some related
cleanups (new fake nops and alt_group struct) objtool can finally be rid
of fake jumps, which were a constant source of headaches.
[1] https://lkml.kernel.org/r/20201111170536.arx2zbn4ngvjoov7@treble
Cc: Shinichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Create a new struct associated with each group of alternatives
instructions. This will help with the removal of fake jumps, and more
importantly with adding support for stack layout changes in
alternatives.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Currently objtool headers are being included either by their base name
or included via ../ from a parent directory. In case of a base name usage:
#include "warn.h"
#include "arch_elf.h"
it does not make it apparent from which directory the file comes from.
To make it slightly better, and actually to avoid name clashes some arch
specific files have "arch_" suffix. And files from an arch folder have
to revert to including via ../ e.g:
#include "../../elf.h"
With additional architectures support and the code base growth there is
a need for clearer headers naming scheme for multiple reasons:
1. to make it instantly obvious where these files come from (objtool
itself / objtool arch|generic folders / some other external files),
2. to avoid name clashes of objtool arch specific headers, potential
obtool arch generic headers and the system header files (there is
/usr/include/elf.h already),
3. to avoid ../ includes and improve code readability.
4. to give a warm fuzzy feeling to developers who are mostly kernel
developers and are accustomed to linux kernel headers arranging
scheme.
Doesn't this make it instantly obvious where are these files come from?
#include <objtool/warn.h>
#include <arch/elf.h>
And doesn't it look nicer to avoid ugly ../ includes? Which also
guarantees this is elf.h from the objtool and not /usr/include/elf.h.
#include <objtool/elf.h>
This patch defines and implements new objtool headers arranging
scheme. Which is:
- all generic headers go to include/objtool (similar to include/linux)
- all arch headers go to arch/$(SRCARCH)/include/arch (to get arch
prefix). This is similar to linux arch specific "asm/*" headers but we
are not abusing "asm" name and calling it what it is. This also helps
to prevent name clashes (arch is not used in system headers or kernel
exports).
To bring objtool to this state the following things are done:
1. current top level tools/objtool/ headers are moved into
include/objtool/ subdirectory,
2. arch specific headers, currently only arch/x86/include/ are moved into
arch/x86/include/arch/ and were stripped of "arch_" suffix,
3. new -I$(srctree)/tools/objtool/include include path to make
includes like <objtool/warn.h> possible,
4. rewriting file includes,
5. make git not to ignore include/objtool/ subdirectory.
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
