Enum Place 

pub enum Place {
    Written,
    ReadOnly,
    RelocReadOnly {
        local: bool,
    },
    Zero,
    Merged,
    Named(String),
}

Which section a variable goes in.

Worked out from what the variable is rather than named by it, except in the one case where the program named it. A reader who wants to know why a variable is in .rodata should be able to find the answer in the variable.

Variants

Written

Written to, and its image is not all zeros. .data.

ReadOnly

Never written to, so it can go in a page the loader maps read only and every process running the program can share. .rodata.

RelocReadOnly

Never written to by the program, but written once by the dynamic linker, because its image holds the address of something and an address is not known until the image is loaded. .data.rel.ro.

The section has to be writable for that one write and read only afterwards, which is what the PT_GNU_RELRO segment is: the loader maps it, the relocations are applied, and then it is turned read only before the program starts. Putting the variable in .rodata instead means asking the linker to leave a relocation in a section that is never writable, and what it does about that is give the whole image DT_TEXTREL, which gives up the protection the section was for. Some hardened toolchains refuse the link outright.

Fields

local: bool

Whether every address in the image is of something this file defines and does not export, which means the link can resolve them all and none can be interposed.

Those go in .data.rel.ro.local, which the linker puts in the first pages of the segment, so the pages holding them are the ones the loader is done with soonest. It is a hint about layout rather than a difference in what the section is.

Zero

All zeros, so the file says how big it is and carries none of it. .bss.

Merged

A tentative definition, which is not in a section at all: the linker is asked for that much zeroed space and merges every definition of the name into one. .comm.

Named(String)

The section the program named, from __attribute__((section(...))).

Trait Implementations

impl Clone for Place

fn clone(&self) -> Place

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Place

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for Place

impl PartialEq for Place

fn eq(&self, other: &Place) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for Place