linux-stable.git/tools/objtool/check.c, branch v5.16.9

objtool: Fix truncated string warning

2022-02-08T17:35:18+00:00

[ Upstream commit 82880283d7fcd0a1d20964a56d6d1a5cc0df0713 ]

On GCC 12, the build fails due to a possible truncated string:

    check.c: In function 'validate_call':
    check.c:2865:58: error: '%d' directive output may be truncated writing between 1 and 10 bytes into a region of size 9 [-Werror=format-truncation=]
     2865 |                 snprintf(pvname, sizeof(pvname), "pv_ops[%d]", idx);
          |                                                          ^~

In theory it's a valid bug:

    static char pvname[16];
    int idx;
    ...
    idx = (rel->addend / sizeof(void *));
    snprintf(pvname, sizeof(pvname), "pv_ops[%d]", idx);

There are only 7 chars for %d while it could take up to 9, so the
printed "pv_ops[%d]" string could get truncated.

In reality the bug should never happen, because pv_ops only has ~80
entries, so 7 chars for the integer is more than enough.  Still, it's
worth fixing.  Bump the buffer size by 2 bytes to silence the warning.

[ jpoimboe: changed size to 19; massaged changelog ]

Fixes: db2b0c5d7b6f ("objtool: Support pv_opsindirect calls for noinstr")
Reported-by: Adam Borowski 
Reported-by: Martin Liška 
Signed-off-by: Sergei Trofimovich 
Signed-off-by: Josh Poimboeuf 
Link: https://lore.kernel.org/r/20220120233748.2062559-1-slyich@gmail.com
Signed-off-by: Sasha Levin

static_call,x86: Robustify trampoline patching

2021-11-11T12:09:31+00:00

Add a few signature bytes after the static call trampoline and verify
those bytes match before patching the trampoline. This avoids patching
random other JMPs (such as CFI jump-table entries) instead.

These bytes decode as:

   d:   53                      push   %rbx
   e:   43 54                   rex.XB push %r12

And happen to spell "SCT".

Signed-off-by: Peter Zijlstra (Intel) 
Link: https://lkml.kernel.org/r/20211030074758.GT174703@worktop.programming.kicks-ass.net

Merge tag 'trace-v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

2021-11-02T03:05:19+00:00

Pull tracing updates from Steven Rostedt:

 - kprobes: Restructured stack unwinder to show properly on x86 when a
   stack dump happens from a kretprobe callback.

 - Fix to bootconfig parsing

 - Have tracefs allow owner and group permissions by default (only
   denying others). There's been pressure to allow non root to tracefs
   in a controlled fashion, and using groups is probably the safest.

 - Bootconfig memory managament updates.

 - Bootconfig clean up to have the tools directory be less dependent on
   changes in the kernel tree.

 - Allow perf to be traced by function tracer.

 - Rewrite of function graph tracer to be a callback from the function
   tracer instead of having its own trampoline (this change will happen
   on an arch by arch basis, and currently only x86_64 implements it).

 - Allow multiple direct trampolines (bpf hooks to functions) be batched
   together in one synchronization.

 - Allow histogram triggers to add variables that can perform
   calculations against the event's fields.

 - Use the linker to determine architecture callbacks from the ftrace
   trampoline to allow for proper parameter prototypes and prevent
   warnings from the compiler.

 - Extend histogram triggers to key off of variables.

 - Have trace recursion use bit magic to determine preempt context over
   if branches.

 - Have trace recursion disable preemption as all use cases do anyway.

 - Added testing for verification of tracing utilities.

 - Various small clean ups and fixes.

* tag 'trace-v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (101 commits)
  tracing/histogram: Fix semicolon.cocci warnings
  tracing/histogram: Fix documentation inline emphasis warning
  tracing: Increase PERF_MAX_TRACE_SIZE to handle Sentinel1 and docker together
  tracing: Show size of requested perf buffer
  bootconfig: Initialize ret in xbc_parse_tree()
  ftrace: do CPU checking after preemption disabled
  ftrace: disable preemption when recursion locked
  tracing/histogram: Document expression arithmetic and constants
  tracing/histogram: Optimize division by a power of 2
  tracing/histogram: Covert expr to const if both operands are constants
  tracing/histogram: Simplify handling of .sym-offset in expressions
  tracing: Fix operator precedence for hist triggers expression
  tracing: Add division and multiplication support for hist triggers
  tracing: Add support for creating hist trigger variables from literal
  selftests/ftrace: Stop tracing while reading the trace file by default
  MAINTAINERS: Update KPROBES and TRACING entries
  test_kprobes: Move it from kernel/ to lib/
  docs, kprobes: Remove invalid URL and add new reference
  samples/kretprobes: Fix return value if register_kretprobe() failed
  lib/bootconfig: Fix the xbc_get_info kerneldoc
  ...

objtool,x86: Replace alternatives with .retpoline_sites

2021-10-28T21:25:25+00:00

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) 
Reviewed-by: Borislav Petkov 
Acked-by: Josh Poimboeuf 
Tested-by: Alexei Starovoitov 
Link: https://lore.kernel.org/r/20211026120309.850007165@infradead.org

objtool: Shrink struct instruction

2021-10-28T21:25:25+00:00

Any one instruction can only ever call a single function, therefore
insn->mcount_loc_node is superfluous and can use insn->call_node.

This shrinks struct instruction, which is by far the most numerous
structure objtool creates.

Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Borislav Petkov 
Acked-by: Josh Poimboeuf 
Tested-by: Alexei Starovoitov 
Link: https://lore.kernel.org/r/20211026120309.785456706@infradead.org

objtool: Explicitly avoid self modifying code in .altinstr_replacement

2021-10-28T21:25:25+00:00

Assume ALTERNATIVE()s know what they're doing and do not change, or
cause to change, instructions in .altinstr_replacement sections.

Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Borislav Petkov 
Acked-by: Josh Poimboeuf 
Tested-by: Alexei Starovoitov 
Link: https://lore.kernel.org/r/20211026120309.722511775@infradead.org

objtool: Classify symbols

2021-10-28T21:25:24+00:00

In order to avoid calling str*cmp() on symbol names, over and over, do
them all once upfront and store the result.

Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Borislav Petkov 
Acked-by: Josh Poimboeuf 
Tested-by: Alexei Starovoitov 
Link: https://lore.kernel.org/r/20211026120309.658539311@infradead.org

Merge branch 'objtool/urgent'

2021-10-06T22:40:17+00:00

Fixup conflicts.

# Conflicts:
#	tools/objtool/check.c

objtool: Remove redundant 'len' field from struct section

2021-10-05T19:03:21+00:00

The section structure already contains sh_size, so just remove the extra
'len' member that requires extra mirroring and potential confusion.

Suggested-by: Josh Poimboeuf 
Signed-off-by: Joe Lawrence 
Reviewed-by: Miroslav Benes 
Signed-off-by: Josh Poimboeuf 
Link: https://lore.kernel.org/r/20210822225037.54620-3-joe.lawrence@redhat.com
Cc: Andy Lavr 
Cc: Peter Zijlstra 
Cc: x86@kernel.org
Cc: linux-kernel@vger.kernel.org

objtool: Ignore unwind hints for ignored functions

2021-10-01T01:24:07+00:00

If a function is ignored, also ignore its hints.  This is useful for the
case where the function ignore is conditional on frame pointers, e.g.
STACK_FRAME_NON_STANDARD_FP().

Link: https://lkml.kernel.org/r/163163048317.489837.10988954983369863209.stgit@devnote2

Signed-off-by: Josh Poimboeuf 
Reviewed-by: Masami Hiramatsu 
Tested-by: Masami Hiramatsu 
Signed-off-by: Steven Rostedt (VMware)