linux.git/tools/objtool, branch v5.10.135

objtool: Fix elf_create_undef_symbol() endianness

2022-07-25T09:26:56+00:00

commit 46c7405df7de8deb97229eacebcee96d61415f3f upstream.

Currently x86 cross-compilation fails on big endian system with:

  x86_64-cross-ld: init/main.o: invalid string offset 488112128 >= 6229 for section `.strtab'

Mark new ELF data in elf_create_undef_symbol() as symbol, so that libelf
does endianness handling correctly.

Fixes: 2f2f7e47f052 ("objtool: Add elf_create_undef_symbol()")
Signed-off-by: Vasily Gorbik 
Signed-off-by: Ingo Molnar 
Acked-by: Peter Zijlstra 
Link: https://lore.kernel.org/r/patch-1.thread-6c9df9.git-d39264656387.your-ad-here.call-01620841104-ext-2554@work.hours
Signed-off-by: Greg Kroah-Hartman

x86/retbleed: Add fine grained Kconfig knobs

2022-07-25T09:26:50+00:00

commit f43b9876e857c739d407bc56df288b0ebe1a9164 upstream.

Do fine-grained Kconfig for all the various retbleed parts.

NOTE: if your compiler doesn't support return thunks this will
silently 'upgrade' your mitigation to IBPB, you might not like this.

Signed-off-by: Peter Zijlstra (Intel) 
Signed-off-by: Borislav Petkov 
[cascardo: there is no CONFIG_OBJTOOL]
[cascardo: objtool calling and option parsing has changed]
Signed-off-by: Thadeu Lima de Souza Cascardo 
[bwh: Backported to 5.10:
 - In scripts/Makefile.build, add the objtool option with an ifdef
   block, same as for other options
 - Adjust filename, context]
Signed-off-by: Ben Hutchings 
Signed-off-by: Greg Kroah-Hartman

objtool: Re-add UNWIND_HINT_{SAVE_RESTORE}

2022-07-25T09:26:47+00:00

commit 8faea26e611189e933ea2281975ff4dc7c1106b6 upstream.

Commit

  c536ed2fffd5 ("objtool: Remove SAVE/RESTORE hints")

removed the save/restore unwind hints because they were no longer
needed. Now they're going to be needed again so re-add them.

Signed-off-by: Josh Poimboeuf 
Signed-off-by: Peter Zijlstra (Intel) 
Signed-off-by: Borislav Petkov 
Signed-off-by: Thadeu Lima de Souza Cascardo 
Signed-off-by: Ben Hutchings 
Signed-off-by: Greg Kroah-Hartman

objtool: Add entry UNRET validation

2022-07-25T09:26:45+00:00

commit a09a6e2399ba0595c3042b3164f3ca68a3cff33e upstream.

Since entry asm is tricky, add a validation pass that ensures the
retbleed mitigation has been done before the first actual RET
instruction.

Entry points are those that either have UNWIND_HINT_ENTRY, which acts
as UNWIND_HINT_EMPTY but marks the instruction as an entry point, or
those that have UWIND_HINT_IRET_REGS at +0.

This is basically a variant of validate_branch() that is
intra-function and it will simply follow all branches from marked
entry points and ensures that all paths lead to ANNOTATE_UNRET_END.

If a path hits RET or an indirection the path is a fail and will be
reported.

There are 3 ANNOTATE_UNRET_END instances:

 - UNTRAIN_RET itself
 - exception from-kernel; this path doesn't need UNTRAIN_RET
 - all early exceptions; these also don't need UNTRAIN_RET

Signed-off-by: Peter Zijlstra (Intel) 
Signed-off-by: Borislav Petkov 
Reviewed-by: Josh Poimboeuf 
Signed-off-by: Borislav Petkov 
[cascardo: arch/x86/entry/entry_64.S no pt_regs return at .Lerror_entry_done_lfence]
[cascardo: tools/objtool/builtin-check.c no link option validation]
[cascardo: tools/objtool/check.c opts.ibt is ibt]
[cascardo: tools/objtool/include/objtool/builtin.h leave unret option as bool, no struct opts]
[cascardo: objtool is still called from scripts/link-vmlinux.sh]
[cascardo: no IBT support]
Signed-off-by: Thadeu Lima de Souza Cascardo 
[bwh: Backported to 5.10:
 - In scripts/link-vmlinux.sh, use "test -n" instead of is_enabled
 - Adjust context]
Signed-off-by: Ben Hutchings 
Signed-off-by: Greg Kroah-Hartman

objtool: Update Retpoline validation

2022-07-25T09:26:44+00:00

commit 9bb2ec608a209018080ca262f771e6a9ff203b6f upstream.

Update retpoline validation with the new CONFIG_RETPOLINE requirement of
not having bare naked RET instructions.

Signed-off-by: Peter Zijlstra (Intel) 
Signed-off-by: Borislav Petkov 
Reviewed-by: Josh Poimboeuf 
Signed-off-by: Borislav Petkov 
[cascardo: conflict fixup at arch/x86/xen/xen-head.S]
Signed-off-by: Thadeu Lima de Souza Cascardo 
Signed-off-by: Ben Hutchings 
Signed-off-by: Greg Kroah-Hartman

x86: Add magic AMD return-thunk

2022-07-25T09:26:40+00:00

commit a149180fbcf336e97ce4eb2cdc13672727feb94d upstream.

Note: needs to be in a section distinct from Retpolines such that the
Retpoline RET substitution cannot possibly use immediate jumps.

ORC unwinding for zen_untrain_ret() and __x86_return_thunk() is a
little tricky but works due to the fact that zen_untrain_ret() doesn't
have any stack ops and as such will emit a single ORC entry at the
start (+0x3f).

Meanwhile, unwinding an IP, including the __x86_return_thunk() one
(+0x40) will search for the largest ORC entry smaller or equal to the
IP, these will find the one ORC entry (+0x3f) and all works.

  [ Alexandre: SVM part. ]
  [ bp: Build fix, massages. ]

Suggested-by: Andrew Cooper 
Signed-off-by: Peter Zijlstra (Intel) 
Signed-off-by: Borislav Petkov 
Reviewed-by: Josh Poimboeuf 
Signed-off-by: Borislav Petkov 
[cascardo: conflicts at arch/x86/entry/entry_64_compat.S]
[cascardo: there is no ANNOTATE_NOENDBR]
[cascardo: objtool commit 34c861e806478ac2ea4032721defbf1d6967df08 missing]
[cascardo: conflict fixup]
Signed-off-by: Thadeu Lima de Souza Cascardo 
[bwh: Backported to 5.10: SEV-ES is not supported, so drop the change
 in arch/x86/kvm/svm/vmenter.S]
Signed-off-by: Ben Hutchings 
Signed-off-by: Greg Kroah-Hartman

objtool: Treat .text.__x86.* as noinstr

2022-07-25T09:26:39+00:00

commit 951ddecf435659553ed15a9214e153a3af43a9a1 upstream.

Needed because zen_untrain_ret() will be called from noinstr code.

Also makes sense since the thunks MUST NOT contain instrumentation nor
be poked with dynamic instrumentation.

Signed-off-by: Peter Zijlstra (Intel) 
Signed-off-by: Borislav Petkov 
Reviewed-by: Josh Poimboeuf 
Signed-off-by: Borislav Petkov 
Signed-off-by: Thadeu Lima de Souza Cascardo 
Signed-off-by: Ben Hutchings 
Signed-off-by: Greg Kroah-Hartman

objtool: skip non-text sections when adding return-thunk sites

2022-07-25T09:26:37+00:00

The .discard.text section is added in order to reserve BRK, with a
temporary function just so it can give it a size. This adds a relocation to
the return thunk, which objtool will add to the .return_sites section.
Linking will then fail as there are references to the .discard.text
section.

Do not add instructions from non-text sections to the list of return thunk
calls, avoiding the reference to .discard.text.

Signed-off-by: Thadeu Lima de Souza Cascardo 
Acked-by: Josh Poimboeuf 
Signed-off-by: Ben Hutchings 
Signed-off-by: Greg Kroah-Hartman

x86,objtool: Create .return_sites

2022-07-25T09:26:36+00:00

commit d9e9d2300681d68a775c28de6aa6e5290ae17796 upstream.

Find all the return-thunk sites and record them in a .return_sites
section such that the kernel can undo this.

Signed-off-by: Peter Zijlstra (Intel) 
Signed-off-by: Borislav Petkov 
Reviewed-by: Josh Poimboeuf 
Signed-off-by: Borislav Petkov 
[cascardo: conflict fixup because of functions added to support IBT]
Signed-off-by: Thadeu Lima de Souza Cascardo 
[bwh: Backported to 5.10: adjust context]
Signed-off-by: Ben Hutchings 
Signed-off-by: Greg Kroah-Hartman

objtool: Fix objtool regression on x32 systems

2022-07-25T09:26:33+00:00

commit 22682a07acc308ef78681572e19502ce8893c4d4 upstream.

Commit c087c6e7b551 ("objtool: Fix type of reloc::addend") failed to
appreciate cross building from ILP32 hosts, where 'int' == 'long' and
the issue persists.

As such, use s64/int64_t/Elf64_Sxword for this field and suffer the
pain that is ISO C99 printf formats for it.

Fixes: c087c6e7b551 ("objtool: Fix type of reloc::addend")
Signed-off-by: Mikulas Patocka 
[peterz: reword changelog, s/long long/s64/]
Signed-off-by: Peter Zijlstra (Intel) 
Signed-off-by: Borislav Petkov 
Cc: 
Link: https://lkml.kernel.org/r/alpine.LRH.2.02.2205161041260.11556@file01.intranet.prod.int.rdu2.redhat.com
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Ben Hutchings 
Signed-off-by: Greg Kroah-Hartman