linux/tools/objtool, branch v5.19

Merge tag 'x86_bugs_retbleed' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2022-07-12T01:15:25Z

Pull x86 retbleed fixes from Borislav Petkov: "Just when you thought that all the speculation bugs were addressed and solved and the nightmare is complete, here's the next one: speculating after RET instructions and leaking privileged information using the now pretty much classical covert channels. It is called RETBleed and the mitigation effort and controlling functionality has been modelled similar to what already existing mitigations provide" * tag 'x86_bugs_retbleed' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (54 commits) x86/speculation: Disable RRSBA behavior x86/kexec: Disable RET on kexec x86/bugs: Do not enable IBPB-on-entry when IBPB is not supported x86/entry: Move PUSH_AND_CLEAR_REGS() back into error_entry x86/bugs: Add Cannon lake to RETBleed affected CPU list x86/retbleed: Add fine grained Kconfig knobs x86/cpu/amd: Enumerate BTC_NO x86/common: Stamp out the stepping madness KVM: VMX: Prevent RSB underflow before vmenter x86/speculation: Fill RSB on vmexit for IBRS KVM: VMX: Fix IBRS handling after vmexit KVM: VMX: Prevent guest RSB poisoning attacks with eIBRS KVM: VMX: Convert launched argument to flags KVM: VMX: Flatten __vmx_vcpu_run() objtool: Re-add UNWIND_HINT_{SAVE_RESTORE} x86/speculation: Remove x86_spec_ctrl_mask x86/speculation: Use cached host SPEC_CTRL value for guest entry/exit x86/speculation: Fix SPEC_CTRL write on SMT state change x86/speculation: Fix firmware entry SPEC_CTRL handling x86/speculation: Fix RSB filling with CONFIG_RETPOLINE=n ...

x86/ibt, objtool: Don't discard text references from tracepoint section

2022-07-07T11:26:54Z

On Tue, Jun 28, 2022 at 04:28:58PM +0800, Pengfei Xu wrote: > # ./ftracetest > === Ftrace unit tests === > [1] Basic trace file check [PASS] > [2] Basic test for tracers [PASS] > [3] Basic trace clock test [PASS] > [4] Basic event tracing check [PASS] > [5] Change the ringbuffer size [PASS] > [6] Snapshot and tracing setting [PASS] > [7] trace_pipe and trace_marker [PASS] > [8] Test ftrace direct functions against tracers [UNRESOLVED] > [9] Test ftrace direct functions against kprobes [UNRESOLVED] > [10] Generic dynamic event - add/remove eprobe events [FAIL] > [11] Generic dynamic event - add/remove kprobe events > > It 100% reproduced in step 11 and then missing ENDBR BUG generated: > " > [ 9332.752836] mmiotrace: enabled CPU7. > [ 9332.788612] mmiotrace: disabled. > [ 9337.103426] traps: Missing ENDBR: syscall_regfunc+0x0/0xb0 It turns out that while syscall_regfunc() does have an ENDBR when generated, it gets sealed by objtool's .ibt_endbr_seal list. Since the only text references to this function: $ git grep syscall_regfunc include/linux/tracepoint.h:extern int syscall_regfunc(void); include/trace/events/syscalls.h: syscall_regfunc, syscall_unregfunc include/trace/events/syscalls.h: syscall_regfunc, syscall_unregfunc kernel/tracepoint.c:int syscall_regfunc(void) appear in the __tracepoint section which is excluded by objtool. Fixes: 3c6f9f77e618 ("objtool: Rework ibt and extricate from stack validation") Reported-by: Pengfei Xu Link: https://lkml.kernel.org/r/Yrrepdaow4F5kqG0@hirez.programming.kicks-ass.net

x86/retbleed: Add fine grained Kconfig knobs

2022-06-29T15:43:41Z

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

objtool: Re-add UNWIND_HINT_{SAVE_RESTORE}

2022-06-27T08:34:00Z

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

objtool: Add entry UNRET validation

2022-06-27T08:34:00Z

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

objtool: Update Retpoline validation

2022-06-27T08:33:59Z

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

x86: Add magic AMD return-thunk

2022-06-27T08:33:59Z

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

objtool: Treat .text.__x86.* as noinstr

2022-06-27T08:33:59Z

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

x86,objtool: Create .return_sites

2022-06-27T08:33:58Z

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

x86/extable: Annotate ex_handler_msr_mce() as a dead end

2022-05-27T10:34:45Z

Fix vmlinux.o: warning: objtool: fixup_exception+0x2d6: unreachable instruction Signed-off-by: Borislav Petkov Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20220520192729.23969-1-bp@alien8.de