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Commit be5ec363 authored by Martin Schwidefsky's avatar Martin Schwidefsky
Browse files

[S390] No execute support cleanup. 



Simplify the signal_return function that checks for the two special
system calls sigreturn and rt_sigreturn. No need to do a page table
walk, a call to copy_from_user while disabled page faults will work
as well.

Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
parent 10c1031f

arch/s390/mm/fault.c

+21 −51
Original line number Diff line number Diff line
@@ -26,9 +26,9 @@ 
#include <linux/module.h>

#include <linux/hardirq.h>

#include <linux/kprobes.h>

#include <linux/uaccess.h>



#include <asm/system.h>

#include <asm/uaccess.h>

#include <asm/pgtable.h>

#include <asm/kdebug.h>

#include <asm/s390_ext.h>
@@ -263,68 +263,38 @@ extern long sys_rt_sigreturn(struct pt_regs *regs); 
extern long sys32_sigreturn(struct pt_regs *regs);

extern long sys32_rt_sigreturn(struct pt_regs *regs);



static inline void do_sigreturn(struct mm_struct *mm, struct pt_regs *regs,

				int rt)

static int signal_return(struct mm_struct *mm, struct pt_regs *regs,

			 unsigned long address, unsigned long error_code)

{

	u16 instruction;

	int rc, compat;



	pagefault_disable();

	rc = __get_user(instruction, (u16 __user *) regs->psw.addr);

	pagefault_enable();

	if (rc)

		return -EFAULT;



	up_read(&mm->mmap_sem);

	clear_tsk_thread_flag(current, TIF_SINGLE_STEP);

#ifdef CONFIG_COMPAT

	if (test_tsk_thread_flag(current, TIF_31BIT)) {

		if (rt)

			sys32_rt_sigreturn(regs);

		else

	compat = test_tsk_thread_flag(current, TIF_31BIT);

	if (compat && instruction == 0x0a77)

		sys32_sigreturn(regs);

		return;

	}

#endif /* CONFIG_COMPAT */

	if (rt)

		sys_rt_sigreturn(regs);

	else if (compat && instruction == 0x0aad)

		sys32_rt_sigreturn(regs);

	else

#endif

	if (instruction == 0x0a77)

		sys_sigreturn(regs);

	return;

}



static int signal_return(struct mm_struct *mm, struct pt_regs *regs,

			 unsigned long address, unsigned long error_code)

{

	pgd_t *pgd;

	pmd_t *pmd;

	pte_t *pte;

	u16 *instruction;

	unsigned long pfn, uaddr = regs->psw.addr;



	spin_lock(&mm->page_table_lock);

	pgd = pgd_offset(mm, uaddr);

	if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))

		goto out_fault;

	pmd = pmd_offset(pgd, uaddr);

	if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))

		goto out_fault;

	pte = pte_offset_map(pmd_offset(pgd_offset(mm, uaddr), uaddr), uaddr);

	if (!pte || !pte_present(*pte))

		goto out_fault;

	pfn = pte_pfn(*pte);

	if (!pfn_valid(pfn))

		goto out_fault;

	spin_unlock(&mm->page_table_lock);



	instruction = (u16 *) ((pfn << PAGE_SHIFT) + (uaddr & (PAGE_SIZE-1)));

	if (*instruction == 0x0a77)

		do_sigreturn(mm, regs, 0);

	else if (*instruction == 0x0aad)

		do_sigreturn(mm, regs, 1);

	else if (instruction == 0x0aad)

		sys_rt_sigreturn(regs);

	else {

		printk("- XXX - do_exception: task = %s, primary, NO EXEC "

		       "-> SIGSEGV\n", current->comm);

		up_read(&mm->mmap_sem);

		current->thread.prot_addr = address;

		current->thread.trap_no = error_code;

		do_sigsegv(regs, error_code, SEGV_MAPERR, address);

	}

	return 0;

out_fault:

	spin_unlock(&mm->page_table_lock);

	return -EFAULT;

}

#endif /* CONFIG_S390_EXEC_PROTECT */