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Commit 99cd1302 authored by Ram Pai's avatar Ram Pai Committed by Michael Ellerman
Browse files

powerpc: Deliver SEGV signal on pkey violation 



The value of the pkey, whose protection got violated,
is made available in si_pkey field of the siginfo structure.

Signed-off-by: default avatarRam Pai <linuxram@us.ibm.com>
Signed-off-by: default avatarThiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 087003e9

arch/powerpc/include/asm/bug.h

+1 −0
Original line number Diff line number Diff line
@@ -133,6 +133,7 @@ struct pt_regs; 
extern int do_page_fault(struct pt_regs *, unsigned long, unsigned long);

extern void bad_page_fault(struct pt_regs *, unsigned long, int);

extern void _exception(int, struct pt_regs *, int, unsigned long);

extern void _exception_pkey(int, struct pt_regs *, int, unsigned long, int);

extern void die(const char *, struct pt_regs *, long);

extern bool die_will_crash(void);

arch/powerpc/kernel/traps.c

+11 −1
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ 
#include <linux/sched/debug.h>

#include <linux/kernel.h>

#include <linux/mm.h>

#include <linux/pkeys.h>

#include <linux/stddef.h>

#include <linux/unistd.h>

#include <linux/ptrace.h>
@@ -266,7 +267,9 @@ void user_single_step_siginfo(struct task_struct *tsk, 
	info->si_addr = (void __user *)regs->nip;

}



void _exception(int signr, struct pt_regs *regs, int code, unsigned long addr)



void _exception_pkey(int signr, struct pt_regs *regs, int code,

		unsigned long addr, int key)

{

	siginfo_t info;

	const char fmt32[] = KERN_INFO "%s[%d]: unhandled signal %d " \
@@ -293,9 +296,16 @@ void _exception(int signr, struct pt_regs *regs, int code, unsigned long addr) 
	info.si_signo = signr;

	info.si_code = code;

	info.si_addr = (void __user *) addr;

	info.si_pkey = key;



	force_sig_info(signr, &info, current);

}



void _exception(int signr, struct pt_regs *regs, int code, unsigned long addr)

{

	_exception_pkey(signr, regs, code, addr, 0);

}



void system_reset_exception(struct pt_regs *regs)

{

	/*

arch/powerpc/mm/fault.c

+27 −12
Original line number Diff line number Diff line
@@ -107,7 +107,8 @@ static bool store_updates_sp(struct pt_regs *regs) 
 */



static int

__bad_area_nosemaphore(struct pt_regs *regs, unsigned long address, int si_code)

__bad_area_nosemaphore(struct pt_regs *regs, unsigned long address, int si_code,

		int pkey)

{

	/*

	 * If we are in kernel mode, bail out with a SEGV, this will
@@ -117,17 +118,18 @@ __bad_area_nosemaphore(struct pt_regs *regs, unsigned long address, int si_code) 
	if (!user_mode(regs))

		return SIGSEGV;



	_exception(SIGSEGV, regs, si_code, address);

	_exception_pkey(SIGSEGV, regs, si_code, address, pkey);



	return 0;

}



static noinline int bad_area_nosemaphore(struct pt_regs *regs, unsigned long address)

{

	return __bad_area_nosemaphore(regs, address, SEGV_MAPERR);

	return __bad_area_nosemaphore(regs, address, SEGV_MAPERR, 0);

}



static int __bad_area(struct pt_regs *regs, unsigned long address, int si_code)

static int __bad_area(struct pt_regs *regs, unsigned long address, int si_code,

			int pkey)

{

	struct mm_struct *mm = current->mm;
@@ -137,12 +139,18 @@ static int __bad_area(struct pt_regs *regs, unsigned long address, int si_code) 
	 */

	up_read(&mm->mmap_sem);



	return __bad_area_nosemaphore(regs, address, si_code);

	return __bad_area_nosemaphore(regs, address, si_code, pkey);

}



static noinline int bad_area(struct pt_regs *regs, unsigned long address)

{

	return __bad_area(regs, address, SEGV_MAPERR);

	return __bad_area(regs, address, SEGV_MAPERR, 0);

}



static int bad_key_fault_exception(struct pt_regs *regs, unsigned long address,

				    int pkey)

{

	return __bad_area_nosemaphore(regs, address, SEGV_PKUERR, pkey);

}



static int do_sigbus(struct pt_regs *regs, unsigned long address,
@@ -427,10 +435,9 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address, 


	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);



	if (error_code & DSISR_KEYFAULT) {

		_exception(SIGSEGV, regs, SEGV_PKUERR, address);

		return 0;

	}

	if (error_code & DSISR_KEYFAULT)

		return bad_key_fault_exception(regs, address,

					       get_mm_addr_key(mm, address));



	/*

	 * We want to do this outside mmap_sem, because reading code around nip
@@ -513,10 +520,18 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address, 
	if (unlikely(fault & VM_FAULT_SIGSEGV) &&

		!arch_vma_access_permitted(vma, flags & FAULT_FLAG_WRITE,

			is_exec, 0)) {

		/*

		 * The PGD-PDT...PMD-PTE tree may not have been fully setup.

		 * Hence we cannot walk the tree to locate the PTE, to locate

		 * the key. Hence let's use vma_pkey() to get the key; instead

		 * of get_mm_addr_key().

		 */

		int pkey = vma_pkey(vma);



		if (likely(pkey))

			return __bad_area(regs, address, SEGV_PKUERR);

		if (likely(pkey)) {

			up_read(&mm->mmap_sem);

			return bad_key_fault_exception(regs, address, pkey);

		}

	}

#endif /* CONFIG_PPC_MEM_KEYS */