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-rw-r--r--arch/um/kernel/trap.c251
1 files changed, 251 insertions, 0 deletions
diff --git a/arch/um/kernel/trap.c b/arch/um/kernel/trap.c
new file mode 100644
index 00000000000..ac70fa5a2e2
--- /dev/null
+++ b/arch/um/kernel/trap.c
@@ -0,0 +1,251 @@
+/*
+ * Copyright (C) 2000, 2001 Jeff Dike (jdike@karaya.com)
+ * Licensed under the GPL
+ */
+
+#include "linux/kernel.h"
+#include "asm/errno.h"
+#include "linux/sched.h"
+#include "linux/mm.h"
+#include "linux/spinlock.h"
+#include "linux/config.h"
+#include "linux/init.h"
+#include "linux/ptrace.h"
+#include "asm/semaphore.h"
+#include "asm/pgtable.h"
+#include "asm/pgalloc.h"
+#include "asm/tlbflush.h"
+#include "asm/a.out.h"
+#include "asm/current.h"
+#include "asm/irq.h"
+#include "sysdep/sigcontext.h"
+#include "user_util.h"
+#include "kern_util.h"
+#include "kern.h"
+#include "chan_kern.h"
+#include "mconsole_kern.h"
+#include "mem.h"
+#include "mem_kern.h"
+#include "sysdep/sigcontext.h"
+#include "sysdep/ptrace.h"
+#include "os.h"
+#ifdef CONFIG_MODE_SKAS
+#include "skas.h"
+#endif
+#include "os.h"
+
+/* Note this is constrained to return 0, -EFAULT, -EACCESS, -ENOMEM by segv(). */
+int handle_page_fault(unsigned long address, unsigned long ip,
+ int is_write, int is_user, int *code_out)
+{
+ struct mm_struct *mm = current->mm;
+ struct vm_area_struct *vma;
+ pgd_t *pgd;
+ pud_t *pud;
+ pmd_t *pmd;
+ pte_t *pte;
+ int err = -EFAULT;
+
+ *code_out = SEGV_MAPERR;
+
+ /* If the fault was during atomic operation, don't take the fault, just
+ * fail. */
+ if (in_atomic())
+ goto out_nosemaphore;
+
+ down_read(&mm->mmap_sem);
+ vma = find_vma(mm, address);
+ if(!vma)
+ goto out;
+ else if(vma->vm_start <= address)
+ goto good_area;
+ else if(!(vma->vm_flags & VM_GROWSDOWN))
+ goto out;
+ else if(is_user && !ARCH_IS_STACKGROW(address))
+ goto out;
+ else if(expand_stack(vma, address))
+ goto out;
+
+good_area:
+ *code_out = SEGV_ACCERR;
+ if(is_write && !(vma->vm_flags & VM_WRITE))
+ goto out;
+
+ /* Don't require VM_READ|VM_EXEC for write faults! */
+ if(!is_write && !(vma->vm_flags & (VM_READ | VM_EXEC)))
+ goto out;
+
+ do {
+survive:
+ switch (handle_mm_fault(mm, vma, address, is_write)){
+ case VM_FAULT_MINOR:
+ current->min_flt++;
+ break;
+ case VM_FAULT_MAJOR:
+ current->maj_flt++;
+ break;
+ case VM_FAULT_SIGBUS:
+ err = -EACCES;
+ goto out;
+ case VM_FAULT_OOM:
+ err = -ENOMEM;
+ goto out_of_memory;
+ default:
+ BUG();
+ }
+ pgd = pgd_offset(mm, address);
+ pud = pud_offset(pgd, address);
+ pmd = pmd_offset(pud, address);
+ pte = pte_offset_kernel(pmd, address);
+ } while(!pte_present(*pte));
+ err = 0;
+ /* The below warning was added in place of
+ * pte_mkyoung(); if (is_write) pte_mkdirty();
+ * If it's triggered, we'd see normally a hang here (a clean pte is
+ * marked read-only to emulate the dirty bit).
+ * However, the generic code can mark a PTE writable but clean on a
+ * concurrent read fault, triggering this harmlessly. So comment it out.
+ */
+#if 0
+ WARN_ON(!pte_young(*pte) || (is_write && !pte_dirty(*pte)));
+#endif
+ flush_tlb_page(vma, address);
+out:
+ up_read(&mm->mmap_sem);
+out_nosemaphore:
+ return(err);
+
+/*
+ * We ran out of memory, or some other thing happened to us that made
+ * us unable to handle the page fault gracefully.
+ */
+out_of_memory:
+ if (current->pid == 1) {
+ up_read(&mm->mmap_sem);
+ yield();
+ down_read(&mm->mmap_sem);
+ goto survive;
+ }
+ goto out;
+}
+
+void segv_handler(int sig, union uml_pt_regs *regs)
+{
+ struct faultinfo * fi = UPT_FAULTINFO(regs);
+
+ if(UPT_IS_USER(regs) && !SEGV_IS_FIXABLE(fi)){
+ bad_segv(*fi, UPT_IP(regs));
+ return;
+ }
+ segv(*fi, UPT_IP(regs), UPT_IS_USER(regs), regs);
+}
+
+struct kern_handlers handlinfo_kern = {
+ .relay_signal = relay_signal,
+ .winch = winch,
+ .bus_handler = relay_signal,
+ .page_fault = segv_handler,
+ .sigio_handler = sigio_handler,
+ .timer_handler = timer_handler
+};
+/*
+ * We give a *copy* of the faultinfo in the regs to segv.
+ * This must be done, since nesting SEGVs could overwrite
+ * the info in the regs. A pointer to the info then would
+ * give us bad data!
+ */
+unsigned long segv(struct faultinfo fi, unsigned long ip, int is_user, void *sc)
+{
+ struct siginfo si;
+ void *catcher;
+ int err;
+ int is_write = FAULT_WRITE(fi);
+ unsigned long address = FAULT_ADDRESS(fi);
+
+ if(!is_user && (address >= start_vm) && (address < end_vm)){
+ flush_tlb_kernel_vm();
+ return(0);
+ }
+ else if(current->mm == NULL)
+ panic("Segfault with no mm");
+
+ if (SEGV_IS_FIXABLE(&fi) || SEGV_MAYBE_FIXABLE(&fi))
+ err = handle_page_fault(address, ip, is_write, is_user, &si.si_code);
+ else {
+ err = -EFAULT;
+ /* A thread accessed NULL, we get a fault, but CR2 is invalid.
+ * This code is used in __do_copy_from_user() of TT mode. */
+ address = 0;
+ }
+
+ catcher = current->thread.fault_catcher;
+ if(!err)
+ return(0);
+ else if(catcher != NULL){
+ current->thread.fault_addr = (void *) address;
+ do_longjmp(catcher, 1);
+ }
+ else if(current->thread.fault_addr != NULL)
+ panic("fault_addr set but no fault catcher");
+ else if(!is_user && arch_fixup(ip, sc))
+ return(0);
+
+ if(!is_user)
+ panic("Kernel mode fault at addr 0x%lx, ip 0x%lx",
+ address, ip);
+
+ if (err == -EACCES) {
+ si.si_signo = SIGBUS;
+ si.si_errno = 0;
+ si.si_code = BUS_ADRERR;
+ si.si_addr = (void __user *)address;
+ current->thread.arch.faultinfo = fi;
+ force_sig_info(SIGBUS, &si, current);
+ } else if (err == -ENOMEM) {
+ printk("VM: killing process %s\n", current->comm);
+ do_exit(SIGKILL);
+ } else {
+ BUG_ON(err != -EFAULT);
+ si.si_signo = SIGSEGV;
+ si.si_addr = (void __user *) address;
+ current->thread.arch.faultinfo = fi;
+ force_sig_info(SIGSEGV, &si, current);
+ }
+ return(0);
+}
+
+void bad_segv(struct faultinfo fi, unsigned long ip)
+{
+ struct siginfo si;
+
+ si.si_signo = SIGSEGV;
+ si.si_code = SEGV_ACCERR;
+ si.si_addr = (void __user *) FAULT_ADDRESS(fi);
+ current->thread.arch.faultinfo = fi;
+ force_sig_info(SIGSEGV, &si, current);
+}
+
+void relay_signal(int sig, union uml_pt_regs *regs)
+{
+ if(arch_handle_signal(sig, regs)) return;
+ if(!UPT_IS_USER(regs))
+ panic("Kernel mode signal %d", sig);
+ current->thread.arch.faultinfo = *UPT_FAULTINFO(regs);
+ force_sig(sig, current);
+}
+
+void bus_handler(int sig, union uml_pt_regs *regs)
+{
+ if(current->thread.fault_catcher != NULL)
+ do_longjmp(current->thread.fault_catcher, 1);
+ else relay_signal(sig, regs);
+}
+
+void winch(int sig, union uml_pt_regs *regs)
+{
+ do_IRQ(WINCH_IRQ, regs);
+}
+
+void trap_init(void)
+{
+}
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2024-12-02 22:14:43 +0000