Right now, we'll leak memory when we display a help topic because we
don't free t, s, d that we've just used when breaking out of the loop.
NB: coverity just reported t, but s and d also leak.
CID: 1007776
Always free dev and fstyp before strduping new values to assign to
them. Free them at the end of the loop. This keeps them from leaking
for mal-formed /etc/fstab lines.
CID: 1007777, 1007778, 1007779
Sponsored by: Netflix
ELF object files can contain program sections which are not supposed
to be loaded into memory (e.g. .comment). Normally the static linker
uses these flags to decide which sections are allocated to loadable
program segments in ELF binaries and shared objects (including kernels
on all architectures and kernel modules on architectures other than
amd64).
Mapping ELF object files (such as amd64 kernel modules) into memory
directly is a bit of a grey area. ELF object files are intended to be
used as inputs to the static linker. As a result, there is not a
standardized definition for what the memory layout of an ELF object
should be (none of the section headers have valid virtual memory
addresses for example).
The kernel and loader were not checking the SHF_ALLOC flag but loading
any program sections with certain types such as SHT_PROGBITS. As a
result, the kernel and loader would load into RAM some sections that
weren't marked with SHF_ALLOC such as .comment that are not loaded
into RAM for kernel modules on other architectures (which are
implemented as ELF shared objects). Aside from possibly requiring
slightly more RAM to hold a kernel module this does not affect runtime
correctness as the kernel relocates symbols based on the layout it
uses.
Debuggers such as gdb and lldb do not extract symbol tables from a
running process or kernel. Instead, they replicate the memory layout
of ELF executables and shared objects and use that to construct their
own symbol tables. For executables and shared objects this works
fine. For ELF objects the current logic in kgdb (and probably lldb
based on a simple reading) assumes that only sections with SHF_ALLOC
are memory resident when constructing a memory layout. If the
debugger constructs a different memory layout than the kernel, then it
will compute different addresses for symbols causing symbols in the
debugger to appear to have the wrong values (though the kernel itself
is working fine). The current port of mdb does not check SHF_ALLOC as
it replicates the kernel's logic in its existing kernel support.
The bfd linker sorts the sections in ELF object files such that all of
the allocated sections (sections with SHF_ALLOCATED) are placed first
followed by unallocated sections. As a result, when kgdb composed a
memory layout using only the allocated sections, this layout happened
to match the layout used by the kernel and loader. The lld linker
does not sort the sections in ELF object files and mixed allocated and
unallocated sections. This resulted in kgdb composing a different
memory layout than the kernel and loader.
We could either patch kgdb (and possibly in the future lldb) to use
custom handling when generating memory layouts for kernel modules that
are ELF objects, or we could change the kernel and loader to check
SHF_ALLOCATED. I chose the latter as I feel we shouldn't be loading
things into RAM that the module won't use. This should mostly be a
NOP when linking with bfd but will allow the existing kgdb to work
with amd64 kernel modules linked with lld.
Note that we only require SHF_ALLOC for "program" sections for types
like SHT_PROGBITS and SHT_NOBITS. Other section types such as symbol
tables, string tables, and relocations must also be loaded and are not
marked with SHF_ALLOC.
Reported by: np
Reviewed by: kib, emaste
MFC after: 1 month
Sponsored by: Chelsio Communications
Differential Revision: https://reviews.freebsd.org/D13926
ifuncs can be only called in the (early boot) kernel environment, so
postpone resolving until early stage of the kernel boot. This commit
is performed in advance to make loaders on most machines updated
before ifuncs appear in the kernels.
Reviewed by: emaste, jhb
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D13838
removing this argument, and expanding when rc is NULL. This
effectively completes the back out of custom scripts for tftp booted
loaders from r269153 that was started in r292344 with the new path
tricks that obsoleted it.
Submitted by: Netflix
Don't print when we can't find a file. Copy it instead to the error
buffer. Higher level routines determine if it's appropriate to print
the error message.
Also, remove dead code (labeled bogusly lost functionality) since we
never used that functionality. Remove unused arg from interact() too.
Sponsored by: Netflix
Create an interp class. Use it to separate out the different types of
interpreters: forth and simple with function pointers rather than
via #ifdefs.
Obtained from: lua boot loader project
(via https://bsdimp@github.com/bsdimp/freebsd.git lua-bootloader)
Sponsored by: Netflix
latter aren't used. Prefer sys/link_elf.h to link.h so we're only
dependent on the kernel tree. The default installation of link.h just
includes this file, and any benefit from that is outweighed by the
hassle it causes. This reduces the footprint of files needed from the
system includes (or sysroot in buildworld).
Sponsored by: Netflix
greater than 2^31-1, then the result will be huge. This is unlikely,
as we don't support that many sections, but out of an abundace of
caution cast to size_t so the multiplication won't overflow
mysteriously when size_t is larger than 32-bits. The resulting code
may be a smidge larger, but this isn't super-space critical code.
CID: 1194216, 1194217, 1194222, 1194223, 1265018, 1265019,1265020,
1265021
Sponsored by: Netflix
