[REVIEW][PATCH 15/22] signal/s390: Use force_sig_fault where appropriate

From: Eric W. Biederman
Date: Fri Apr 20 2018 - 10:47:21 EST


Filling in struct siginfo before calling force_sig_info a tedious and
error prone process, where once in a great while the wrong fields
are filled out, and siginfo has been inconsistently cleared.

Simplify this process by using the helper force_sig_fault. Which
takes as a parameters all of the information it needs, ensures
all of the fiddly bits of filling in struct siginfo are done properly
and then calls force_sig_info.

In short about a 5 line reduction in code for every time force_sig_info
is called, which makes the calling function clearer.

Cc: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Cc: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Cc: linux-s390@xxxxxxxxxxxxxxx
Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
---
arch/s390/kernel/traps.c | 32 ++++++--------------------------
arch/s390/mm/fault.c | 23 ++++++-----------------
2 files changed, 12 insertions(+), 43 deletions(-)

diff --git a/arch/s390/kernel/traps.c b/arch/s390/kernel/traps.c
index 3ba649d8aa5a..8003b38c1688 100644
--- a/arch/s390/kernel/traps.c
+++ b/arch/s390/kernel/traps.c
@@ -44,15 +44,8 @@ int is_valid_bugaddr(unsigned long addr)

void do_report_trap(struct pt_regs *regs, int si_signo, int si_code, char *str)
{
- siginfo_t info;
-
if (user_mode(regs)) {
- clear_siginfo(&info);
- info.si_signo = si_signo;
- info.si_errno = 0;
- info.si_code = si_code;
- info.si_addr = get_trap_ip(regs);
- force_sig_info(si_signo, &info, current);
+ force_sig_fault(si_signo, si_code, get_trap_ip(regs), current);
report_user_fault(regs, si_signo, 0);
} else {
const struct exception_table_entry *fixup;
@@ -81,19 +74,12 @@ NOKPROBE_SYMBOL(do_trap);

void do_per_trap(struct pt_regs *regs)
{
- siginfo_t info;
-
if (notify_die(DIE_SSTEP, "sstep", regs, 0, 0, SIGTRAP) == NOTIFY_STOP)
return;
if (!current->ptrace)
return;
- clear_siginfo(&info);
- info.si_signo = SIGTRAP;
- info.si_errno = 0;
- info.si_code = TRAP_HWBKPT;
- info.si_addr =
- (void __force __user *) current->thread.per_event.address;
- force_sig_info(SIGTRAP, &info, current);
+ force_sig_fault(SIGTRAP, TRAP_HWBKPT,
+ (void __force __user *) current->thread.per_event.address, current);
}
NOKPROBE_SYMBOL(do_per_trap);

@@ -178,15 +164,9 @@ void illegal_op(struct pt_regs *regs)
if (get_user(*((__u16 *) opcode), (__u16 __user *) location))
return;
if (*((__u16 *) opcode) == S390_BREAKPOINT_U16) {
- if (current->ptrace) {
- siginfo_t info;
- clear_siginfo(&info);
- info.si_signo = SIGTRAP;
- info.si_errno = 0;
- info.si_code = TRAP_BRKPT;
- info.si_addr = location;
- force_sig_info(SIGTRAP, &info, current);
- } else
+ if (current->ptrace)
+ force_sig_fault(SIGTRAP, TRAP_BRKPT, location, current);
+ else
signal = SIGILL;
#ifdef CONFIG_UPROBES
} else if (*((__u16 *) opcode) == UPROBE_SWBP_INSN) {
diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index b3ff0e8e5860..e074480d3598 100644
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -265,15 +265,10 @@ void report_user_fault(struct pt_regs *regs, long signr, int is_mm_fault)
*/
static noinline void do_sigsegv(struct pt_regs *regs, int si_code)
{
- struct siginfo si;
-
report_user_fault(regs, SIGSEGV, 1);
- clear_siginfo(&si);
- si.si_signo = SIGSEGV;
- si.si_errno = 0;
- si.si_code = si_code;
- si.si_addr = (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK);
- force_sig_info(SIGSEGV, &si, current);
+ force_sig_fault(SIGSEGV, si_code,
+ (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK),
+ current);
}

static noinline void do_no_context(struct pt_regs *regs)
@@ -317,19 +312,13 @@ static noinline void do_low_address(struct pt_regs *regs)

static noinline void do_sigbus(struct pt_regs *regs)
{
- struct task_struct *tsk = current;
- struct siginfo si;
-
/*
* Send a sigbus, regardless of whether we were in kernel
* or user mode.
*/
- clear_siginfo(&si);
- si.si_signo = SIGBUS;
- si.si_errno = 0;
- si.si_code = BUS_ADRERR;
- si.si_addr = (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK);
- force_sig_info(SIGBUS, &si, tsk);
+ force_sig_fault(SIGBUS, BUS_ADRERR,
+ (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK),
+ current);
}

static noinline int signal_return(struct pt_regs *regs)
--
2.14.1