Struct ExTable

pub(crate) struct ExTable;

A structure representing the usage of exception table (ExTable). This table is used for recovering from specific exception handling faults occurring at known points in the code.

To add a recovery instruction for a target assembly instruction, one should add the following statements:

.pushsection .ex_table, "a"
.align 8
.quad [.target_label],
.quad [.recovery_label],
.popsection

where the target_label and recovery_label are the labels of the target instruction and the label of recovery instruction respectively.

For example, we have the following assembly code snippets in an input file:

.label1:    
    rep movsb
    mov rax, rcx
.label2:
    ret

We can add the following statements in the same file (label1 and label2 are local labels):

.pushsection .ex_table, "a"
.align 8
.quad [.label1],
.quad [.label2],
.popsection

After that, we can use the API of ExTable to resume execution when handling exceptions caused by rep movsb (which label1 point to) failing.

Implementations

impl ExTable

pub fn find_recovery_inst_addr(inst_addr: Vaddr) -> Option<Vaddr>

Finds the recovery instruction address for a given instruction address.

This function is generally used when an exception (such as a page fault) occurs. if the exception handling fails and there is a predefined recovery action, then the found recovery action will be taken.