Re: [REVIEW][PATCH 08/22] signal/mips: Use force_sig_fault where appropriate
From: Matt Redfearn
Date: Wed May 09 2018 - 11:18:35 EST
Hi Eric,
On 20/04/18 15:37, Eric W. Biederman wrote:
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: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Cc: James Hogan <jhogan@xxxxxxxxxx>
Cc: linux-mips@xxxxxxxxxxxxxx
Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
---
arch/mips/kernel/traps.c | 65 ++++++++++++++----------------------------------
arch/mips/mm/fault.c | 19 ++++----------
2 files changed, 23 insertions(+), 61 deletions(-)
diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
index 967e9e4e795e..66ec4b0b484d 100644
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -699,17 +699,11 @@ static int simulate_sync(struct pt_regs *regs, unsigned int opcode)
asmlinkage void do_ov(struct pt_regs *regs)
{
enum ctx_state prev_state;
- siginfo_t info;
-
- clear_siginfo(&info);
- info.si_signo = SIGFPE;
- info.si_code = FPE_INTOVF;
- info.si_addr = (void __user *)regs->cp0_epc;
prev_state = exception_enter();
die_if_kernel("Integer overflow", regs);
- force_sig_info(SIGFPE, &info, current);
+ force_sig_fault(SIGFPE, FPE_INTOVF, (void __user *)regs->cp0_epc, current);
exception_exit(prev_state);
}
@@ -722,32 +716,27 @@ asmlinkage void do_ov(struct pt_regs *regs)
void force_fcr31_sig(unsigned long fcr31, void __user *fault_addr,
struct task_struct *tsk)
{
- struct siginfo si;
-
- clear_siginfo(&si);
- si.si_addr = fault_addr;
- si.si_signo = SIGFPE;
+ int si_code;
This is giving build errors in Linux next
(https://storage.kernelci.org/next/master/next-20180509/mips/defconfig+kselftest/build.log)
si_code would have ended up as 0 before from the clear_siginfo(), but
perhaps
int si_code = FPE_FLTUNK;
Would make a more sensible default?
Thanks,
Matt
if (fcr31 & FPU_CSR_INV_X)
- si.si_code = FPE_FLTINV;
+ si_code = FPE_FLTINV;
else if (fcr31 & FPU_CSR_DIV_X)
- si.si_code = FPE_FLTDIV;
+ si_code = FPE_FLTDIV;
else if (fcr31 & FPU_CSR_OVF_X)
- si.si_code = FPE_FLTOVF;
+ si_code = FPE_FLTOVF;
else if (fcr31 & FPU_CSR_UDF_X)
- si.si_code = FPE_FLTUND;
+ si_code = FPE_FLTUND;
else if (fcr31 & FPU_CSR_INE_X)
- si.si_code = FPE_FLTRES;
+ si_code = FPE_FLTRES;
- force_sig_info(SIGFPE, &si, tsk);
+ force_sig_fault(SIGFPE, si_code, fault_addr, tsk);
}
int process_fpemu_return(int sig, void __user *fault_addr, unsigned long fcr31)
{
- struct siginfo si;
+ int si_code;
struct vm_area_struct *vma;
- clear_siginfo(&si);
switch (sig) {
case 0:
return 0;
@@ -757,23 +746,18 @@ int process_fpemu_return(int sig, void __user *fault_addr, unsigned long fcr31)
return 1;
case SIGBUS:
- si.si_addr = fault_addr;
- si.si_signo = sig;
- si.si_code = BUS_ADRERR;
- force_sig_info(sig, &si, current);
+ force_sig_fault(SIGBUS, BUS_ADRERR, fault_addr, current);
return 1;
case SIGSEGV:
- si.si_addr = fault_addr;
- si.si_signo = sig;
down_read(¤t->mm->mmap_sem);
vma = find_vma(current->mm, (unsigned long)fault_addr);
if (vma && (vma->vm_start <= (unsigned long)fault_addr))
- si.si_code = SEGV_ACCERR;
+ si_code = SEGV_ACCERR;
else
- si.si_code = SEGV_MAPERR;
+ si_code = SEGV_MAPERR;
up_read(¤t->mm->mmap_sem);
- force_sig_info(sig, &si, current);
+ force_sig_fault(SIGSEGV, si_code, fault_addr, current);
return 1;
default:
@@ -896,10 +880,8 @@ asmlinkage void do_fpe(struct pt_regs *regs, unsigned long fcr31)
void do_trap_or_bp(struct pt_regs *regs, unsigned int code, int si_code,
const char *str)
{
- siginfo_t info;
char b[40];
- clear_siginfo(&info);
#ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
if (kgdb_ll_trap(DIE_TRAP, str, regs, code, current->thread.trap_nr,
SIGTRAP) == NOTIFY_STOP)
@@ -921,13 +903,9 @@ void do_trap_or_bp(struct pt_regs *regs, unsigned int code, int si_code,
case BRK_DIVZERO:
scnprintf(b, sizeof(b), "%s instruction in kernel code", str);
die_if_kernel(b, regs);
- if (code == BRK_DIVZERO)
- info.si_code = FPE_INTDIV;
- else
- info.si_code = FPE_INTOVF;
- info.si_signo = SIGFPE;
- info.si_addr = (void __user *) regs->cp0_epc;
- force_sig_info(SIGFPE, &info, current);
+ force_sig_fault(SIGFPE,
+ code == BRK_DIVZERO ? FPE_INTDIV : FPE_INTOVF,
+ (void __user *) regs->cp0_epc, current);
break;
case BRK_BUG:
die_if_kernel("Kernel bug detected", regs);
@@ -952,9 +930,7 @@ void do_trap_or_bp(struct pt_regs *regs, unsigned int code, int si_code,
scnprintf(b, sizeof(b), "%s instruction in kernel code", str);
die_if_kernel(b, regs);
if (si_code) {
- info.si_signo = SIGTRAP;
- info.si_code = si_code;
- force_sig_info(SIGTRAP, &info, current);
+ force_sig_fault(SIGTRAP, si_code, NULL, current);
} else {
force_sig(SIGTRAP, current);
}
@@ -1506,13 +1482,8 @@ asmlinkage void do_mdmx(struct pt_regs *regs)
*/
asmlinkage void do_watch(struct pt_regs *regs)
{
- siginfo_t info;
enum ctx_state prev_state;
- clear_siginfo(&info);
- info.si_signo = SIGTRAP;
- info.si_code = TRAP_HWBKPT;
-
prev_state = exception_enter();
/*
* Clear WP (bit 22) bit of cause register so we don't loop
@@ -1528,7 +1499,7 @@ asmlinkage void do_watch(struct pt_regs *regs)
if (test_tsk_thread_flag(current, TIF_LOAD_WATCH)) {
mips_read_watch_registers();
local_irq_enable();
- force_sig_info(SIGTRAP, &info, current);
+ force_sig_fault(SIGTRAP, TRAP_HWBKPT, NULL, current);
} else {
mips_clear_watch_registers();
local_irq_enable();
diff --git a/arch/mips/mm/fault.c b/arch/mips/mm/fault.c
index 75392becd933..5f71f2b903b7 100644
--- a/arch/mips/mm/fault.c
+++ b/arch/mips/mm/fault.c
@@ -42,7 +42,7 @@ static void __kprobes __do_page_fault(struct pt_regs *regs, unsigned long write,
struct task_struct *tsk = current;
struct mm_struct *mm = tsk->mm;
const int field = sizeof(unsigned long) * 2;
- siginfo_t info;
+ int si_code;
int fault;
unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
@@ -63,8 +63,7 @@ static void __kprobes __do_page_fault(struct pt_regs *regs, unsigned long write,
return;
#endif
- clear_siginfo(&info);
- info.si_code = SEGV_MAPERR;
+ si_code = SEGV_MAPERR;
/*
* We fault-in kernel-space virtual memory on-demand. The
@@ -113,7 +112,7 @@ static void __kprobes __do_page_fault(struct pt_regs *regs, unsigned long write,
* we can handle it..
*/
good_area:
- info.si_code = SEGV_ACCERR;
+ si_code = SEGV_ACCERR;
if (write) {
if (!(vma->vm_flags & VM_WRITE))
@@ -224,11 +223,7 @@ static void __kprobes __do_page_fault(struct pt_regs *regs, unsigned long write,
pr_cont("\n");
}
current->thread.trap_nr = (regs->cp0_cause >> 2) & 0x1f;
- info.si_signo = SIGSEGV;
- info.si_errno = 0;
- /* info.si_code has been set above */
- info.si_addr = (void __user *) address;
- force_sig_info(SIGSEGV, &info, tsk);
+ force_sig_fault(SIGSEGV, si_code, (void __user *)address, tsk);
return;
}
@@ -284,11 +279,7 @@ static void __kprobes __do_page_fault(struct pt_regs *regs, unsigned long write,
#endif
current->thread.trap_nr = (regs->cp0_cause >> 2) & 0x1f;
tsk->thread.cp0_badvaddr = address;
- info.si_signo = SIGBUS;
- info.si_errno = 0;
- info.si_code = BUS_ADRERR;
- info.si_addr = (void __user *) address;
- force_sig_info(SIGBUS, &info, tsk);
+ force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)address, tsk);
return;
#ifndef CONFIG_64BIT