linux.git/tools/objtool, branch v5.15.71

x86/retbleed: Add fine grained Kconfig knobs

2022-07-23T10:54:10+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 
Signed-off-by: Greg Kroah-Hartman

objtool: Re-add UNWIND_HINT_{SAVE_RESTORE}

2022-07-23T10:54:08+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: Greg Kroah-Hartman

objtool: Add entry UNRET validation

2022-07-23T10:54:06+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: 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 
Signed-off-by: Greg Kroah-Hartman

objtool: Update Retpoline validation

2022-07-23T10:54:04+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: Greg Kroah-Hartman

x86: Add magic AMD return-thunk

2022-07-23T10:54:01+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 
Signed-off-by: Greg Kroah-Hartman

objtool: Treat .text.__x86.* as noinstr

2022-07-23T10:54:01+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: Greg Kroah-Hartman

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

2022-07-23T10:53:58+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: Greg Kroah-Hartman

x86,objtool: Create .return_sites

2022-07-23T10:53:58+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 
Signed-off-by: Greg Kroah-Hartman

objtool: Default ignore INT3 for unreachable

2022-07-23T10:53:56+00:00

commit 1ffbe4e935f9b7308615c75be990aec07464d1e7 upstream.

Ignore all INT3 instructions for unreachable code warnings, similar to NOP.
This allows using INT3 for various paddings instead of NOPs.

Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Josh Poimboeuf 
Link: https://lore.kernel.org/r/20220308154317.343312938@infradead.org
Signed-off-by: Thadeu Lima de Souza Cascardo 
Signed-off-by: Greg Kroah-Hartman

objtool: Introduce CFI hash

2022-07-23T10:53:51+00:00

commit 8b946cc38e063f0f7bb67789478c38f6d7d457c9 upstream.

Andi reported that objtool on vmlinux.o consumes more memory than his
system has, leading to horrific performance.

This is in part because we keep a struct instruction for every
instruction in the file in-memory. Shrink struct instruction by
removing the CFI state (which includes full register state) from it
and demand allocating it.

Given most instructions don't actually change CFI state, there's lots
of repetition there, so add a hash table to find previous CFI
instances.

Reduces memory consumption (and runtime) for processing an
x86_64-allyesconfig:

  pre:  4:40.84 real,   143.99 user,    44.18 sys,      30624988 mem
  post: 2:14.61 real,   108.58 user,    25.04 sys,      16396184 mem

Suggested-by: Andi Kleen 
Signed-off-by: Peter Zijlstra (Intel) 
Link: https://lore.kernel.org/r/20210624095147.756759107@infradead.org
Signed-off-by: Thadeu Lima de Souza Cascardo 
Signed-off-by: Greg Kroah-Hartman