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[S390] fault handler performance optimization.
Slim down the do_exception function to handle only the fast path of a fault and move the exceptional cases into a new function. That slightly increases the performance of the fault handling. Build fix for !CONFIG_COMPAT by Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Martin Schwidefsky
Martin Schwidefsky
parent
7ecb344ae8
commit
50d7280d43
@ -34,16 +34,15 @@
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#include <asm/pgtable.h>
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#include <asm/s390_ext.h>
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#include <asm/mmu_context.h>
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#include <asm/compat.h>
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#include "../kernel/entry.h"
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#ifndef CONFIG_64BIT
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#define __FAIL_ADDR_MASK 0x7ffff000
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#define __FIXUP_MASK 0x7fffffff
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#define __SUBCODE_MASK 0x0200
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#define __PF_RES_FIELD 0ULL
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#else /* CONFIG_64BIT */
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#define __FAIL_ADDR_MASK -4096L
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#define __FIXUP_MASK ~0L
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#define __SUBCODE_MASK 0x0600
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#define __PF_RES_FIELD 0x8000000000000000ULL
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#endif /* CONFIG_64BIT */
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@ -52,6 +51,10 @@
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extern int sysctl_userprocess_debug;
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#endif
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#define VM_FAULT_BADCONTEXT 0x010000
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#define VM_FAULT_BADMAP 0x020000
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#define VM_FAULT_BADACCESS 0x040000
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static inline int notify_page_fault(struct pt_regs *regs)
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{
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int ret = 0;
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@ -122,18 +125,22 @@ static inline int user_space_fault(unsigned long trans_exc_code)
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* Send SIGSEGV to task. This is an external routine
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* to keep the stack usage of do_page_fault small.
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*/
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static void do_sigsegv(struct pt_regs *regs, unsigned long error_code,
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int si_code, unsigned long address)
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static noinline void do_sigsegv(struct pt_regs *regs, long int_code,
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int si_code, unsigned long trans_exc_code)
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{
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struct siginfo si;
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unsigned long address;
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address = trans_exc_code & __FAIL_ADDR_MASK;
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current->thread.prot_addr = address;
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current->thread.trap_no = int_code;
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#if defined(CONFIG_SYSCTL) || defined(CONFIG_PROCESS_DEBUG)
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#if defined(CONFIG_SYSCTL)
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if (sysctl_userprocess_debug)
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#endif
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{
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printk("User process fault: interruption code 0x%lX\n",
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error_code);
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int_code);
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printk("failing address: %lX\n", address);
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show_regs(regs);
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}
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@ -144,14 +151,14 @@ static void do_sigsegv(struct pt_regs *regs, unsigned long error_code,
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force_sig_info(SIGSEGV, &si, current);
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}
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static void do_no_context(struct pt_regs *regs, unsigned long error_code,
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unsigned long trans_exc_code)
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static noinline void do_no_context(struct pt_regs *regs, long int_code,
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unsigned long trans_exc_code)
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{
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const struct exception_table_entry *fixup;
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unsigned long address;
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/* Are we prepared to handle this kernel fault? */
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fixup = search_exception_tables(regs->psw.addr & __FIXUP_MASK);
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fixup = search_exception_tables(regs->psw.addr & PSW_ADDR_INSN);
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if (fixup) {
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regs->psw.addr = fixup->fixup | PSW_ADDR_AMODE;
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return;
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@ -169,107 +176,127 @@ static void do_no_context(struct pt_regs *regs, unsigned long error_code,
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printk(KERN_ALERT "Unable to handle kernel paging request"
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" at virtual user address %p\n", (void *)address);
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die("Oops", regs, error_code);
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die("Oops", regs, int_code);
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do_exit(SIGKILL);
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}
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static void do_low_address(struct pt_regs *regs, unsigned long error_code,
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unsigned long trans_exc_code)
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static noinline void do_low_address(struct pt_regs *regs, long int_code,
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unsigned long trans_exc_code)
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{
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/* Low-address protection hit in kernel mode means
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NULL pointer write access in kernel mode. */
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if (regs->psw.mask & PSW_MASK_PSTATE) {
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/* Low-address protection hit in user mode 'cannot happen'. */
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die ("Low-address protection", regs, error_code);
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die ("Low-address protection", regs, int_code);
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do_exit(SIGKILL);
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}
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do_no_context(regs, error_code, trans_exc_code);
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do_no_context(regs, int_code, trans_exc_code);
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}
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static void do_sigbus(struct pt_regs *regs, unsigned long error_code,
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unsigned long trans_exc_code)
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static noinline void do_sigbus(struct pt_regs *regs, long int_code,
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unsigned long trans_exc_code)
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{
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struct task_struct *tsk = current;
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struct mm_struct *mm = tsk->mm;
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up_read(&mm->mmap_sem);
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/*
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* Send a sigbus, regardless of whether we were in kernel
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* or user mode.
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*/
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tsk->thread.prot_addr = trans_exc_code & __FAIL_ADDR_MASK;
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tsk->thread.trap_no = error_code;
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tsk->thread.trap_no = int_code;
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force_sig(SIGBUS, tsk);
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/* Kernel mode? Handle exceptions or die */
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if (!(regs->psw.mask & PSW_MASK_PSTATE))
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do_no_context(regs, error_code, trans_exc_code);
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}
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#ifdef CONFIG_S390_EXEC_PROTECT
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static int signal_return(struct mm_struct *mm, struct pt_regs *regs,
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unsigned long address, unsigned long error_code)
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static noinline int signal_return(struct pt_regs *regs, long int_code,
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unsigned long trans_exc_code)
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{
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u16 instruction;
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int rc;
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#ifdef CONFIG_COMPAT
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int compat;
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#endif
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pagefault_disable();
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rc = __get_user(instruction, (u16 __user *) regs->psw.addr);
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pagefault_enable();
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if (rc)
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return -EFAULT;
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up_read(&mm->mmap_sem);
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clear_tsk_thread_flag(current, TIF_SINGLE_STEP);
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#ifdef CONFIG_COMPAT
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compat = is_compat_task();
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if (compat && instruction == 0x0a77)
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sys32_sigreturn();
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else if (compat && instruction == 0x0aad)
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sys32_rt_sigreturn();
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else
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#endif
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if (instruction == 0x0a77)
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sys_sigreturn();
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else if (instruction == 0x0aad)
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sys_rt_sigreturn();
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else {
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current->thread.prot_addr = address;
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current->thread.trap_no = error_code;
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do_sigsegv(regs, error_code, SEGV_MAPERR, address);
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}
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if (!rc && instruction == 0x0a77) {
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clear_tsk_thread_flag(current, TIF_SINGLE_STEP);
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if (is_compat_task())
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sys32_sigreturn();
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else
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sys_sigreturn();
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} else if (!rc && instruction == 0x0aad) {
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clear_tsk_thread_flag(current, TIF_SINGLE_STEP);
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if (is_compat_task())
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sys32_rt_sigreturn();
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else
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sys_rt_sigreturn();
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} else
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do_sigsegv(regs, int_code, SEGV_MAPERR, trans_exc_code);
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return 0;
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}
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#endif /* CONFIG_S390_EXEC_PROTECT */
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static noinline void do_fault_error(struct pt_regs *regs, long int_code,
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unsigned long trans_exc_code, int fault)
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{
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int si_code;
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switch (fault) {
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case VM_FAULT_BADACCESS:
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#ifdef CONFIG_S390_EXEC_PROTECT
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if ((regs->psw.mask & PSW_MASK_ASC) == PSW_ASC_SECONDARY &&
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(trans_exc_code & 3) == 0) {
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signal_return(regs, int_code, trans_exc_code);
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break;
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}
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#endif /* CONFIG_S390_EXEC_PROTECT */
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case VM_FAULT_BADMAP:
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/* Bad memory access. Check if it is kernel or user space. */
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if (regs->psw.mask & PSW_MASK_PSTATE) {
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/* User mode accesses just cause a SIGSEGV */
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si_code = (fault == VM_FAULT_BADMAP) ?
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SEGV_MAPERR : SEGV_ACCERR;
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do_sigsegv(regs, int_code, si_code, trans_exc_code);
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return;
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}
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case VM_FAULT_BADCONTEXT:
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do_no_context(regs, int_code, trans_exc_code);
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break;
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default: /* fault & VM_FAULT_ERROR */
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if (fault & VM_FAULT_OOM)
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pagefault_out_of_memory();
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else if (fault & VM_FAULT_SIGBUS) {
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do_sigbus(regs, int_code, trans_exc_code);
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/* Kernel mode? Handle exceptions or die */
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if (!(regs->psw.mask & PSW_MASK_PSTATE))
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do_no_context(regs, int_code, trans_exc_code);
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} else
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BUG();
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break;
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}
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}
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/*
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* This routine handles page faults. It determines the address,
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* and the problem, and then passes it off to one of the appropriate
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* routines.
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*
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* error_code:
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* interruption code (int_code):
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* 04 Protection -> Write-Protection (suprression)
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* 10 Segment translation -> Not present (nullification)
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* 11 Page translation -> Not present (nullification)
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* 3b Region third trans. -> Not present (nullification)
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*/
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static inline void
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do_exception(struct pt_regs *regs, unsigned long error_code, int write,
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unsigned long trans_exc_code)
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static inline int do_exception(struct pt_regs *regs, int write,
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unsigned long trans_exc_code)
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{
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struct task_struct *tsk;
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struct mm_struct *mm;
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struct vm_area_struct *vma;
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unsigned long address;
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int si_code;
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int fault;
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if (notify_page_fault(regs))
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return;
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return 0;
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tsk = current;
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mm = tsk->mm;
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@ -279,8 +306,9 @@ do_exception(struct pt_regs *regs, unsigned long error_code, int write,
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* we are not in an interrupt and that there is a
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* user context.
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*/
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fault = VM_FAULT_BADCONTEXT;
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if (unlikely(!user_space_fault(trans_exc_code) || in_atomic() || !mm))
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goto no_context;
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goto out;
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address = trans_exc_code & __FAIL_ADDR_MASK;
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/*
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@ -292,41 +320,35 @@ do_exception(struct pt_regs *regs, unsigned long error_code, int write,
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perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, 0, regs, address);
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down_read(&mm->mmap_sem);
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si_code = SEGV_MAPERR;
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fault = VM_FAULT_BADMAP;
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vma = find_vma(mm, address);
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if (!vma)
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goto bad_area;
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goto out_up;
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if (unlikely(vma->vm_start > address)) {
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if (!(vma->vm_flags & VM_GROWSDOWN))
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goto out_up;
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if (expand_stack(vma, address))
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goto out_up;
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}
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/*
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* Ok, we have a good vm_area for this memory access, so
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* we can handle it..
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*/
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fault = VM_FAULT_BADACCESS;
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#ifdef CONFIG_S390_EXEC_PROTECT
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if (unlikely((regs->psw.mask & PSW_MASK_ASC) == PSW_ASC_SECONDARY &&
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(trans_exc_code & 3) == 0 && !(vma->vm_flags & VM_EXEC)))
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if (!signal_return(mm, regs, address, error_code))
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/*
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* signal_return() has done an up_read(&mm->mmap_sem)
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* if it returns 0.
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*/
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return;
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goto out_up;
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#endif
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if (vma->vm_start <= address)
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goto good_area;
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if (!(vma->vm_flags & VM_GROWSDOWN))
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goto bad_area;
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if (expand_stack(vma, address))
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goto bad_area;
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/*
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* Ok, we have a good vm_area for this memory access, so
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* we can handle it..
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*/
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good_area:
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si_code = SEGV_ACCERR;
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if (!write) {
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/* page not present, check vm flags */
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if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
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goto bad_area;
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goto out_up;
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} else {
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if (!(vma->vm_flags & VM_WRITE))
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goto bad_area;
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goto out_up;
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}
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if (is_vm_hugetlb_page(vma))
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@ -337,17 +359,9 @@ good_area:
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* the fault.
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*/
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fault = handle_mm_fault(mm, vma, address, write ? FAULT_FLAG_WRITE : 0);
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if (unlikely(fault & VM_FAULT_ERROR)) {
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if (fault & VM_FAULT_OOM) {
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up_read(&mm->mmap_sem);
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pagefault_out_of_memory();
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return;
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} else if (fault & VM_FAULT_SIGBUS) {
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do_sigbus(regs, error_code, address);
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return;
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}
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BUG();
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}
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if (unlikely(fault & VM_FAULT_ERROR))
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goto out_up;
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if (fault & VM_FAULT_MAJOR) {
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tsk->maj_flt++;
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perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, 0,
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@ -357,67 +371,55 @@ good_area:
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perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, 0,
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regs, address);
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}
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up_read(&mm->mmap_sem);
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/*
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* The instruction that caused the program check will
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* be repeated. Don't signal single step via SIGTRAP.
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*/
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clear_tsk_thread_flag(tsk, TIF_SINGLE_STEP);
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return;
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/*
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* Something tried to access memory that isn't in our memory map..
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* Fix it, but check if it's kernel or user first..
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*/
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bad_area:
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fault = 0;
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out_up:
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up_read(&mm->mmap_sem);
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/* User mode accesses just cause a SIGSEGV */
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if (regs->psw.mask & PSW_MASK_PSTATE) {
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tsk->thread.prot_addr = address;
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tsk->thread.trap_no = error_code;
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do_sigsegv(regs, error_code, si_code, address);
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return;
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}
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no_context:
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do_no_context(regs, error_code, trans_exc_code);
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out:
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return fault;
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}
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void __kprobes do_protection_exception(struct pt_regs *regs,
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long error_code)
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void __kprobes do_protection_exception(struct pt_regs *regs, long int_code)
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{
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unsigned long trans_exc_code = S390_lowcore.trans_exc_code;
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int fault;
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/* Protection exception is supressing, decrement psw address. */
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regs->psw.addr -= (error_code >> 16);
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regs->psw.addr -= (int_code >> 16);
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/*
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* Check for low-address protection. This needs to be treated
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* as a special case because the translation exception code
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* field is not guaranteed to contain valid data in this case.
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*/
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if (unlikely(!(trans_exc_code & 4))) {
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do_low_address(regs, error_code, trans_exc_code);
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do_low_address(regs, int_code, trans_exc_code);
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return;
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}
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do_exception(regs, 4, 1, trans_exc_code);
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fault = do_exception(regs, 1, trans_exc_code);
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if (unlikely(fault))
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do_fault_error(regs, 4, trans_exc_code, fault);
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}
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void __kprobes do_dat_exception(struct pt_regs *regs, long error_code)
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void __kprobes do_dat_exception(struct pt_regs *regs, long int_code)
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{
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do_exception(regs, error_code & 0xff, 0, S390_lowcore.trans_exc_code);
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unsigned long trans_exc_code = S390_lowcore.trans_exc_code;
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int fault;
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fault = do_exception(regs, 0, trans_exc_code);
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if (unlikely(fault))
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do_fault_error(regs, int_code & 255, trans_exc_code, fault);
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}
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#ifdef CONFIG_64BIT
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void __kprobes do_asce_exception(struct pt_regs *regs, unsigned long error_code)
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void __kprobes do_asce_exception(struct pt_regs *regs, long int_code)
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{
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unsigned long trans_exc_code = S390_lowcore.trans_exc_code;
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struct mm_struct *mm;
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struct mm_struct *mm = current->mm;
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struct vm_area_struct *vma;
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unsigned long address;
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mm = current->mm;
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address = trans_exc_code & __FAIL_ADDR_MASK;
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if (unlikely(!user_space_fault(trans_exc_code) || in_atomic() || !mm))
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goto no_context;
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@ -425,7 +427,7 @@ void __kprobes do_asce_exception(struct pt_regs *regs, unsigned long error_code)
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local_irq_enable();
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down_read(&mm->mmap_sem);
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vma = find_vma(mm, address);
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vma = find_vma(mm, trans_exc_code & __FAIL_ADDR_MASK);
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up_read(&mm->mmap_sem);
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if (vma) {
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@ -435,14 +437,12 @@ void __kprobes do_asce_exception(struct pt_regs *regs, unsigned long error_code)
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/* User mode accesses just cause a SIGSEGV */
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if (regs->psw.mask & PSW_MASK_PSTATE) {
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current->thread.prot_addr = address;
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current->thread.trap_no = error_code;
|
||||
do_sigsegv(regs, error_code, SEGV_MAPERR, address);
|
||||
do_sigsegv(regs, int_code, SEGV_MAPERR, trans_exc_code);
|
||||
return;
|
||||
}
|
||||
|
||||
no_context:
|
||||
do_no_context(regs, error_code, trans_exc_code);
|
||||
do_no_context(regs, int_code, trans_exc_code);
|
||||
}
|
||||
#endif
|
||||
|
||||
@ -507,7 +507,7 @@ void pfault_fini(void)
|
||||
: : "a" (&refbk), "m" (refbk) : "cc");
|
||||
}
|
||||
|
||||
static void pfault_interrupt(__u16 error_code)
|
||||
static void pfault_interrupt(__u16 int_code)
|
||||
{
|
||||
struct task_struct *tsk;
|
||||
__u16 subcode;
|
||||
|
||||
Loading…
Reference in New Issue
Block a user