https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113321
Bug ID: 113321
Summary: x86-64: Make __attribute__((interrupt)) more robust
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: hpa at zytor dot com
Target Milestone: ---
__attribute__((interrupt)) on x86 has two prototypes, and picking the wrong
type "probably will cause a system crash." It turns out that this is
unavoidable on i386, but on x86-64 we can do better:
- On x86-64, an exception/interrupt carries an error code if and only if the
stack is 16-byte aligned (specifically, RSP[3] = 0) on exception entry.
The proper stack pointer for using with IRET is therefore always given by:
RSP |= 8
... and the error code, if present, will be located at offset -8 from this
address.
