On Wed, Jun 05, 2024 at 01:37:23PM -0700, Yang Shi wrote:
+static __always_inline bool aarch64_insn_is_class_cas(u32 insn)This is still pretty opaque if we want to modify it in the future. I
+{
+ return aarch64_insn_is_cas(insn) ||
+ aarch64_insn_is_casp(insn);
+}
+
+/*
+ * Exclude unallocated atomic instructions and LD64B/LDAPR.
+ * The masks and values were generated by using Python sympy module.
+ */
+static __always_inline bool aarch64_atomic_insn_has_wr_perm(u32 insn)
+{
+ return ((insn & 0x3f207c00) == 0x38200000) ||
+ ((insn & 0x3f208c00) == 0x38200000) ||
+ ((insn & 0x7fe06c00) == 0x78202000) ||
+ ((insn & 0xbf204c00) == 0x38200000);
+}
guess we could add more tests on top but it would be nice to have a way
to re-generate these masks. I'll think about, for now these tests would
do.
@@ -511,6 +539,7 @@ static int __kprobes do_page_fault(unsigned long far, unsigned long esr,I think we can get rid of may_force_write and just test (vm_flags &
unsigned long addr = untagged_addr(far);
struct vm_area_struct *vma;
int si_code;
+ bool may_force_write = false;
if (kprobe_page_fault(regs, esr))
return 0;
@@ -547,6 +576,7 @@ static int __kprobes do_page_fault(unsigned long far, unsigned long esr,
/* If EPAN is absent then exec implies read */
if (!alternative_has_cap_unlikely(ARM64_HAS_EPAN))
vm_flags |= VM_EXEC;
+ may_force_write = true;
}
if (is_ttbr0_addr(addr) && is_el1_permission_fault(addr, esr, regs)) {
@@ -568,6 +598,12 @@ static int __kprobes do_page_fault(unsigned long far, unsigned long esr,
if (!vma)
goto lock_mmap;
+ if (may_force_write && (vma->vm_flags & VM_WRITE) &&
+ is_el0_atomic_instr(regs)) {
+ vm_flags = VM_WRITE;
+ mm_flags |= FAULT_FLAG_WRITE;
+ }
VM_READ).