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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: Ram Pai <linuxram@us.ibm.com>
Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Ram Pai 2018-01-18 17:50:42 -08:00 committed by Michael Ellerman
parent 087003e9ef
commit 99cd130232
3 changed files with 39 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
arch/powerpc/include/asm/bug.h
View File

@ -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);

12
arch/powerpc/kernel/traps.c
View File

@ -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)
{
/*

39
arch/powerpc/mm/fault.c
View File

@ -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 @@ good_area:
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 */