[Bug 256899] ELF image activator does not like thumb entry points

From: <bugzilla-noreply_at_freebsd.org>
Date: Wed, 30 Jun 2021 10:31:01 UTC

            Bug ID: 256899
           Summary: ELF image activator does not like thumb entry points
           Product: Base System
           Version: 13.0-RELEASE
          Hardware: arm
                OS: Any
            Status: New
          Severity: Affects Only Me
          Priority: ---
         Component: arm
          Assignee: freebsd-arm@FreeBSD.org
          Reporter: fuz@fuz.su

An ARM ELF binary with an odd entry point should start the binary in Thumb
mode.  However, this does not seem to be the case, forcing the entry point to
be in ARM mode.  To reproduce, copy the following code to a file named test.s:

        .arch armv7a
        .syntax unified
        .globl _start
_start: movs r0, #0
        movs r7, #1
        svc #0

Then assemble and link:

    as -o test.o test.s
    ld -o test test.o

And observe the program crashing on start with a segmentation fault or invalid
instruction exception.  Expected behaviour is that the program terminates with
exit status 0.

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