libelf_relocatedyn() reads the handful of DT_* tags it needs to walk the
relocation tables and ignores the rest. Three more matter now.
DT_PLTGOT is where the object's data base lives. An FDPIC module runs
with that in the PIC base register, and every function descriptor built
for it names the same base as the one its callee should run with, so
without it there is nothing to put in a descriptor's second word.
The DT_*_ARRAY tags are the constructor and destructor tables. These are
already found through the section headers a few lines further down, and
that path is kept, but the dynamic tags are the authoritative copy and an
object is not obliged to carry section headers at all. Both paths now
translate through libelf_addr(), so they agree on the answer rather than
depending on which ran last. The tag values themselves were missing from
include/elf.h and are added.
Sizing the descriptor pool has to happen here rather than later.
R_ARM_FUNCDESC asks the loader to manufacture a descriptor and hand back
its address, which means the space must exist by the time the relocation
is applied, and by then the segment has been placed. So libelf_elfsize()
reserves it behind the writable data, bounded by the relocation count --
one relocation cannot ask for more than one descriptor. That bound has
slack in it, but a descriptor is two words and modules are small, which
is cheaper than walking every relocation twice to get an exact count.
Nothing here runs for a non-FDPIC object. Built and booted
mps3-an547:picostest with no change in behaviour.
Assisted-by: Claude Opus 5 (1M context) <noreply@anthropic.com>
Signed-off-by: Marco Casaroli <marco.casaroli@gmail.com>
An ET_DYN object is loaded into one allocation with its data behind its
text, because its data references sit at a fixed distance from the code
that makes them. An FDPIC object does not work that way: it reaches its
data through a base register, so the two segments can be placed wherever
suits, and the point of the format is that the read-only one is left on
the media and executed there while only the writable one is copied. One
copy of the text then serves every instance.
So libelf_load() grows a second case. The object announces itself in the
OS/ABI byte, which is noted once in libelf_loadhdrs() rather than
re-derived; e_flags cannot be used for this, as an FDPIC object's are an
unremarkable EABI version and testing them would reject every valid
module. Text is taken from the media address plus the segment's own file
offset -- the same arithmetic the ET_REL path already does with
sh_offset -- and libelf_loadfile() does not read it. If the filesystem
cannot show its media, the loader copies the text to RAM instead. The
module then loses the shared text and the flash saving, but it runs.
Obtaining that address needs two mechanisms, and they are not
interchangeable. A compacting filesystem can move a file's blocks, so it
hands out an address only with a pin that holds them still and expects
the pin back; xipfs is the one in tree. A filesystem whose layout never
changes has nothing to hold and answers FIOC_XIPBASE with a bare address;
romfs and tmpfs are those. libelf_xipacquire() asks for the pin first,
because a filesystem that needs one is not safe without it, and
libelf_unload() gives it back. The loader asks for a pin only if it can
hold one, or the pin would stay for ever.
The pin is thus not specific to FDPIC. Any module that executes in place
from a compacting filesystem takes one, and gives it back at unload.
mmap() is not used, though both filesystems implement it. The mapping
would be recorded against whichever task called the loader, while the
release happens when the module's own task exits, which is a different
group -- so the pin would outlive the module and the extent would never
become movable again.
Unloading has to change with placement: the existing path frees only
textalloc because ET_DYN had a single allocation, which would leak an
FDPIC object's data and free media the filesystem only lent us.
Nothing here runs for a non-FDPIC object; every branch is behind the flag
and the single-allocation path is untouched. Built and booted
mps3-an547:picostest, which is CONFIG_ELF with CONFIG_PIC, with no change
in behaviour.
Assisted-by: Claude Opus 5 (1M context) <noreply@anthropic.com>
Signed-off-by: Marco Casaroli <marco.casaroli@gmail.com>
1. use '__attribute__((constructor))' mark initialize function
2. use '__attribute__((destructor))' mark uninitialize function
3. compile module with -fvisibility=hidden. use `__attribute__((visibility("default")))`
mark is need export symbol.so not need module_initialize to initialize export symbol.
Signed-off-by: anjiahao <anjiahao@xiaomi.com>
Most tools used for compliance and SBOM generation use SPDX identifiers
This change brings us a step closer to an easy SBOM generation.
Signed-off-by: Alin Jerpelea <alin.jerpelea@sony.com>
* libs/libc/machine/arm/armv7-m/arch_elf.c
- Fix cast of error message parameters
* build-globals.sh
- Build the modlib_globals.S file used to resolve symbols when dynamically loading
* libs/libc/modlib/Make.defs
- Build modlib_globals.S for all targets
* libs/libc/modlib/modlib_load.c
- Calculate sizes and text/data addresses based on program headers rather than section headers
- Handle objects with no program headers
* libs/libc/modlib/modlib_bind.c
- Call modlib_readsym with pointer to symbol table
- Add modlib_relocatedyn to manage relocation of symbols with shared object (ET_DYN)
- Differentiate between ET_REL and ET_DYN objects
- Use arch independent symbol ELF_R_SYM
- Cast sizes to avoid warnings
* libs/libc/modlib/modlib_load.c
- Cast sizes to avoid warnings
* include/elf.h
- Add definitions that may be found in shared objects
* include/nuttx/lib/modlib.h
- Add parameter to modlib_readsym prototype
- Add prototypes for:
- modlib_insertsymtab
- modlib_findglobal
- Define Elf_Dyn and Elf_Off according to the elf architecture
- Add fields to mod_loadifno_s:
- Program headers
- Exported symbols
- Data section address
- Padding requirement
- Section index for dynamic symbol table
- Number of symbols exported
- Add prottotype for modlib_freesymtab
* libs/libc/dlfcn/lib_dlclose.c
- Free the symbol table when the dll is closed
* libs/libc/dlfcn/lib_dlopen.c
- Add dump of program headers to debug routine
- Differentiate between ET_REL and ET_DYN objects
* libs/libc/machine/arm/armv7-m/arch_elf.c
- Add handling of R_ARM_RELATIVE and R_ARM_JUMP slot relocation types
* libs/libc/modlib/modlib_loadshdrs.c
- Rename modlib_loadshdrs.c to modlib_loadhdrs.c
- Rename modlib_loadshdrs to modlib_loadhdrs
- Add code to load program headers
* libs/libc/modlib/modlib_symbols.c
- Define entry point structure
- Add offset parameter to modlib_symname() and use to find symbol names
- Add symtab section header parameter to modlib_readsym()
- Add offset parameter to modlib_symvalue() to locate symbol names
- Add modlib_insertsyntab() to create a symbol table for exporting and resolution
- Add findEP() to resolve a symbol in the modlib_global table
- Add modlib_findglobal() to find symbol in the modlib_global table
- Add modlib_freesymtab() to free the symbol table
* libs/libc/modlib/modlib_uninit.c
- Free header and sections from a module_loadinfo_s control block
* libs/libc/modlib/modlib_verify.c
- Handle ET_DYN shared objects
* libs/libc/modlib/modlib_globals.S
- Multi-target global table
- Define library APIs that may be resolved when loading a shared object
* include: Introduce elf64.h and elf.h
Added elf64.h for 64bit ELF support and moved common definitions
from elf32.h to elf.h. Also introduced Elf_xxx to be used in
common libraries such as binfmt.
* binfmt, include, modlib, module: Add support for ELF64
Elf_xxx must be used instead of Elf32_xxx to support ELF64.
To use ELF64, CONFIG_ELF_64BIT must be enabled.
* binfmt, modlib: Add support for relocate address
* arch: risc-v: Add include/elf.h
* libs: machine: Add risc-v related files.
NOTE: Currently only supports ELF64
* boards: maix-bit: Add elf and posix_spawn configurations
* boards: maix-bit: Add support for module configuration
