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arm64: mm: unaligned access by user-land should be received as SIGBUS 

After 52d7523 (arm64: mm: allow the kernel to handle alignment faults on
user accesses) commit user-land accesses that produce unaligned exceptions
like in case of aarch32 ldm/stm/ldrd/strd instructions operating on
unaligned memory received by user-land as SIGSEGV. It is wrong, it should
be reported as SIGBUS as it was before 52d7523 commit.

Changed do_bad_area function to take signal and code parameters out of esr
value using fault_info table, so in case of do_alignment_fault fault
user-land will receive SIGBUS. Wrapped access to fault_info table into
esr_to_fault_info function.

Cc: <stable@vger.kernel.org>
Fixes: 52d7523 (arm64: mm: allow the kernel to handle alignment faults on user accesses)
Signed-off-by: Victor Kamensky <kamensky@cisco.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Victor Kamensky 2017-04-03 22:51:01 -07:00 committed by Will Deacon
parent a71c9a1c77
commit 09a6adf53d
1 changed files with 24 additions and 18 deletions
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42
arch/arm64/mm/fault.c
View File

@ -42,7 +42,20 @@
#include <asm/pgtable.h>
#include <asm/tlbflush.h>
static const char *fault_name(unsigned int esr);
struct fault_info {
int (*fn)(unsigned long addr, unsigned int esr,
struct pt_regs *regs);
int sig;
int code;
const char *name;
};
static const struct fault_info fault_info[];
static inline const struct fault_info *esr_to_fault_info(unsigned int esr)
{
return fault_info + (esr & 63);
}
#ifdef CONFIG_KPROBES
static inline int notify_page_fault(struct pt_regs *regs, unsigned int esr)
@ -197,10 +210,12 @@ static void __do_user_fault(struct task_struct *tsk, unsigned long addr,
struct pt_regs *regs)
{
struct siginfo si;
const struct fault_info *inf;
if (unhandled_signal(tsk, sig) && show_unhandled_signals_ratelimited()) {
inf = esr_to_fault_info(esr);
pr_info("%s[%d]: unhandled %s (%d) at 0x%08lx, esr 0x%03x\n",
tsk->comm, task_pid_nr(tsk), fault_name(esr), sig,
tsk->comm, task_pid_nr(tsk), inf->name, sig,
addr, esr);
show_pte(tsk->mm, addr);
show_regs(regs);
@ -219,14 +234,16 @@ static void do_bad_area(unsigned long addr, unsigned int esr, struct pt_regs *re
{
struct task_struct *tsk = current;
struct mm_struct *mm = tsk->active_mm;
const struct fault_info *inf;
/*
* If we are in kernel mode at this point, we have no context to
* handle this fault with.
*/
if (user_mode(regs))
__do_user_fault(tsk, addr, esr, SIGSEGV, SEGV_MAPERR, regs);
else
if (user_mode(regs)) {
inf = esr_to_fault_info(esr);
__do_user_fault(tsk, addr, esr, inf->sig, inf->code, regs);
} else
__do_kernel_fault(mm, addr, esr, regs);
}
@ -488,12 +505,7 @@ static int do_bad(unsigned long addr, unsigned int esr, struct pt_regs *regs)
return 1;
}
static const struct fault_info {
int (*fn)(unsigned long addr, unsigned int esr, struct pt_regs *regs);
int sig;
int code;
const char *name;
} fault_info[] = {
static const struct fault_info fault_info[] = {
{ do_bad, SIGBUS, 0, "ttbr address size fault" },
{ do_bad, SIGBUS, 0, "level 1 address size fault" },
{ do_bad, SIGBUS, 0, "level 2 address size fault" },
@ -560,19 +572,13 @@ static const struct fault_info {
{ do_bad, SIGBUS, 0, "unknown 63" },
};
static const char *fault_name(unsigned int esr)
{
const struct fault_info *inf = fault_info + (esr & 63);
return inf->name;
}
/*
* Dispatch a data abort to the relevant handler.
*/
asmlinkage void __exception do_mem_abort(unsigned long addr, unsigned int esr,
struct pt_regs *regs)
{
const struct fault_info *inf = fault_info + (esr & 63);
const struct fault_info *inf = esr_to_fault_info(esr);
struct siginfo info;
if (!inf->fn(addr, esr, regs))