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// SPDX-License-Identifier: GPL-2.0
#include <linux/err.h>
#include <linux/mm.h>
#include <asm/current.h>
#include <asm/traps.h>
#include <asm/vdso.h>
struct vdso_exception_table_entry {
int insn, fixup;
};
bool fixup_vdso_exception(struct pt_regs *regs, int trapnr,
unsigned long error_code, unsigned long fault_addr)
{
const struct vdso_image *image = current->mm->context.vdso_image;
const struct vdso_exception_table_entry *extable;
unsigned int nr_entries, i;
unsigned long base;
/*
* Do not attempt to fixup #DB or #BP. It's impossible to identify
* whether or not a #DB/#BP originated from within an SGX enclave and
* SGX enclaves are currently the only use case for vDSO fixup.
*/
if (trapnr == X86_TRAP_DB || trapnr == X86_TRAP_BP)
return false;
if (!current->mm->context.vdso)
return false;
base = (unsigned long)current->mm->context.vdso + image->extable_base;
nr_entries = image->extable_len / (sizeof(*extable));
extable = image->extable;
for (i = 0; i < nr_entries; i++) {
if (regs->ip == base + extable[i].insn) {
regs->ip = base + extable[i].fixup;
regs->di = trapnr;
regs->si = error_code;
regs->dx = fault_addr;
return true;
}
}
return false;
}
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