MIPS: Send proper signal and siginfo on FP emulator faults.
We were unconditionally sending SIGBUS with an empty siginfo on FP
emulator faults. This differs from what happens when real floating
point hardware would get a fault.
For most faults we need to send SIGSEGV with the faulting address
filled in in the struct siginfo.
Reported-by: Camm Maguire <camm@maguirefamily.org>
Signed-off-by: David Daney <ddaney@caviumnetworks.com>
To: linux-mips@linux-mips.org
Cc: Camm Maguire <camm@maguirefamily.org>
Patchwork: https://patchwork.linux-mips.org/patch/1727/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
index 8e9fbe7..e971043 100644
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -83,7 +83,8 @@
extern asmlinkage void handle_reserved(void);
extern int fpu_emulator_cop1Handler(struct pt_regs *xcp,
- struct mips_fpu_struct *ctx, int has_fpu);
+ struct mips_fpu_struct *ctx, int has_fpu,
+ void *__user *fault_addr);
void (*board_be_init)(void);
int (*board_be_handler)(struct pt_regs *regs, int is_fixup);
@@ -661,12 +662,36 @@
force_sig_info(SIGFPE, &info, current);
}
+static int process_fpemu_return(int sig, void __user *fault_addr)
+{
+ if (sig == SIGSEGV || sig == SIGBUS) {
+ struct siginfo si = {0};
+ si.si_addr = fault_addr;
+ si.si_signo = sig;
+ if (sig == SIGSEGV) {
+ if (find_vma(current->mm, (unsigned long)fault_addr))
+ si.si_code = SEGV_ACCERR;
+ else
+ si.si_code = SEGV_MAPERR;
+ } else {
+ si.si_code = BUS_ADRERR;
+ }
+ force_sig_info(sig, &si, current);
+ return 1;
+ } else if (sig) {
+ force_sig(sig, current);
+ return 1;
+ } else {
+ return 0;
+ }
+}
+
/*
* XXX Delayed fp exceptions when doing a lazy ctx switch XXX
*/
asmlinkage void do_fpe(struct pt_regs *regs, unsigned long fcr31)
{
- siginfo_t info;
+ siginfo_t info = {0};
if (notify_die(DIE_FP, "FP exception", regs, 0, regs_to_trapnr(regs), SIGFPE)
== NOTIFY_STOP)
@@ -675,6 +700,7 @@
if (fcr31 & FPU_CSR_UNI_X) {
int sig;
+ void __user *fault_addr = NULL;
/*
* Unimplemented operation exception. If we've got the full
@@ -690,7 +716,8 @@
lose_fpu(1);
/* Run the emulator */
- sig = fpu_emulator_cop1Handler(regs, ¤t->thread.fpu, 1);
+ sig = fpu_emulator_cop1Handler(regs, ¤t->thread.fpu, 1,
+ &fault_addr);
/*
* We can't allow the emulated instruction to leave any of
@@ -702,8 +729,7 @@
own_fpu(1); /* Using the FPU again. */
/* If something went wrong, signal */
- if (sig)
- force_sig(sig, current);
+ process_fpemu_return(sig, fault_addr);
return;
} else if (fcr31 & FPU_CSR_INV_X)
@@ -996,11 +1022,11 @@
if (!raw_cpu_has_fpu) {
int sig;
+ void __user *fault_addr = NULL;
sig = fpu_emulator_cop1Handler(regs,
- ¤t->thread.fpu, 0);
- if (sig)
- force_sig(sig, current);
- else
+ ¤t->thread.fpu,
+ 0, &fault_addr);
+ if (!process_fpemu_return(sig, fault_addr))
mt_ase_fp_affinity();
}
diff --git a/arch/mips/math-emu/cp1emu.c b/arch/mips/math-emu/cp1emu.c
index b2ad1b0..d32cb05 100644
--- a/arch/mips/math-emu/cp1emu.c
+++ b/arch/mips/math-emu/cp1emu.c
@@ -64,7 +64,7 @@
#if __mips >= 4 && __mips != 32
static int fpux_emu(struct pt_regs *,
- struct mips_fpu_struct *, mips_instruction);
+ struct mips_fpu_struct *, mips_instruction, void *__user *);
#endif
/* Further private data for which no space exists in mips_fpu_struct */
@@ -208,16 +208,23 @@
* Two instructions if the instruction is in a branch delay slot.
*/
-static int cop1Emulate(struct pt_regs *xcp, struct mips_fpu_struct *ctx)
+static int cop1Emulate(struct pt_regs *xcp, struct mips_fpu_struct *ctx,
+ void *__user *fault_addr)
{
mips_instruction ir;
unsigned long emulpc, contpc;
unsigned int cond;
- if (get_user(ir, (mips_instruction __user *) xcp->cp0_epc)) {
+ if (!access_ok(VERIFY_READ, xcp->cp0_epc, sizeof(mips_instruction))) {
MIPS_FPU_EMU_INC_STATS(errors);
+ *fault_addr = (mips_instruction __user *)xcp->cp0_epc;
return SIGBUS;
}
+ if (__get_user(ir, (mips_instruction __user *) xcp->cp0_epc)) {
+ MIPS_FPU_EMU_INC_STATS(errors);
+ *fault_addr = (mips_instruction __user *)xcp->cp0_epc;
+ return SIGSEGV;
+ }
/* XXX NEC Vr54xx bug workaround */
if ((xcp->cp0_cause & CAUSEF_BD) && !isBranchInstr(&ir))
@@ -245,10 +252,16 @@
#endif
return SIGILL;
}
- if (get_user(ir, (mips_instruction __user *) emulpc)) {
+ if (!access_ok(VERIFY_READ, emulpc, sizeof(mips_instruction))) {
MIPS_FPU_EMU_INC_STATS(errors);
+ *fault_addr = (mips_instruction __user *)emulpc;
return SIGBUS;
}
+ if (__get_user(ir, (mips_instruction __user *) emulpc)) {
+ MIPS_FPU_EMU_INC_STATS(errors);
+ *fault_addr = (mips_instruction __user *)emulpc;
+ return SIGSEGV;
+ }
/* __compute_return_epc() will have updated cp0_epc */
contpc = xcp->cp0_epc;
/* In order not to confuse ptrace() et al, tweak context */
@@ -269,10 +282,17 @@
u64 val;
MIPS_FPU_EMU_INC_STATS(loads);
- if (get_user(val, va)) {
+
+ if (!access_ok(VERIFY_READ, va, sizeof(u64))) {
MIPS_FPU_EMU_INC_STATS(errors);
+ *fault_addr = va;
return SIGBUS;
}
+ if (__get_user(val, va)) {
+ MIPS_FPU_EMU_INC_STATS(errors);
+ *fault_addr = va;
+ return SIGSEGV;
+ }
DITOREG(val, MIPSInst_RT(ir));
break;
}
@@ -284,10 +304,16 @@
MIPS_FPU_EMU_INC_STATS(stores);
DIFROMREG(val, MIPSInst_RT(ir));
- if (put_user(val, va)) {
+ if (!access_ok(VERIFY_WRITE, va, sizeof(u64))) {
MIPS_FPU_EMU_INC_STATS(errors);
+ *fault_addr = va;
return SIGBUS;
}
+ if (__put_user(val, va)) {
+ MIPS_FPU_EMU_INC_STATS(errors);
+ *fault_addr = va;
+ return SIGSEGV;
+ }
break;
}
@@ -297,10 +323,16 @@
u32 val;
MIPS_FPU_EMU_INC_STATS(loads);
- if (get_user(val, va)) {
+ if (!access_ok(VERIFY_READ, va, sizeof(u32))) {
MIPS_FPU_EMU_INC_STATS(errors);
+ *fault_addr = va;
return SIGBUS;
}
+ if (__get_user(val, va)) {
+ MIPS_FPU_EMU_INC_STATS(errors);
+ *fault_addr = va;
+ return SIGSEGV;
+ }
SITOREG(val, MIPSInst_RT(ir));
break;
}
@@ -312,10 +344,16 @@
MIPS_FPU_EMU_INC_STATS(stores);
SIFROMREG(val, MIPSInst_RT(ir));
- if (put_user(val, va)) {
+ if (!access_ok(VERIFY_WRITE, va, sizeof(u32))) {
MIPS_FPU_EMU_INC_STATS(errors);
+ *fault_addr = va;
return SIGBUS;
}
+ if (__put_user(val, va)) {
+ MIPS_FPU_EMU_INC_STATS(errors);
+ *fault_addr = va;
+ return SIGSEGV;
+ }
break;
}
@@ -440,10 +478,17 @@
contpc = (xcp->cp0_epc +
(MIPSInst_SIMM(ir) << 2));
- if (get_user(ir,
+ if (!access_ok(VERIFY_READ, xcp->cp0_epc,
+ sizeof(mips_instruction))) {
+ MIPS_FPU_EMU_INC_STATS(errors);
+ *fault_addr = (mips_instruction __user *)xcp->cp0_epc;
+ return SIGBUS;
+ }
+ if (__get_user(ir,
(mips_instruction __user *) xcp->cp0_epc)) {
MIPS_FPU_EMU_INC_STATS(errors);
- return SIGBUS;
+ *fault_addr = (mips_instruction __user *)xcp->cp0_epc;
+ return SIGSEGV;
}
switch (MIPSInst_OPCODE(ir)) {
@@ -506,9 +551,8 @@
#if __mips >= 4 && __mips != 32
case cop1x_op:{
- int sig;
-
- if ((sig = fpux_emu(xcp, ctx, ir)))
+ int sig = fpux_emu(xcp, ctx, ir, fault_addr);
+ if (sig)
return sig;
break;
}
@@ -604,7 +648,7 @@
DEF3OP(nmsub, dp, ieee754dp_mul, ieee754dp_sub, ieee754dp_neg);
static int fpux_emu(struct pt_regs *xcp, struct mips_fpu_struct *ctx,
- mips_instruction ir)
+ mips_instruction ir, void *__user *fault_addr)
{
unsigned rcsr = 0; /* resulting csr */
@@ -624,10 +668,16 @@
xcp->regs[MIPSInst_FT(ir)]);
MIPS_FPU_EMU_INC_STATS(loads);
- if (get_user(val, va)) {
+ if (!access_ok(VERIFY_READ, va, sizeof(u32))) {
MIPS_FPU_EMU_INC_STATS(errors);
+ *fault_addr = va;
return SIGBUS;
}
+ if (__get_user(val, va)) {
+ MIPS_FPU_EMU_INC_STATS(errors);
+ *fault_addr = va;
+ return SIGSEGV;
+ }
SITOREG(val, MIPSInst_FD(ir));
break;
@@ -638,9 +688,15 @@
MIPS_FPU_EMU_INC_STATS(stores);
SIFROMREG(val, MIPSInst_FS(ir));
+ if (!access_ok(VERIFY_WRITE, va, sizeof(u32))) {
+ MIPS_FPU_EMU_INC_STATS(errors);
+ *fault_addr = va;
+ return SIGBUS;
+ }
if (put_user(val, va)) {
MIPS_FPU_EMU_INC_STATS(errors);
- return SIGBUS;
+ *fault_addr = va;
+ return SIGSEGV;
}
break;
@@ -701,10 +757,16 @@
xcp->regs[MIPSInst_FT(ir)]);
MIPS_FPU_EMU_INC_STATS(loads);
- if (get_user(val, va)) {
+ if (!access_ok(VERIFY_READ, va, sizeof(u64))) {
MIPS_FPU_EMU_INC_STATS(errors);
+ *fault_addr = va;
return SIGBUS;
}
+ if (__get_user(val, va)) {
+ MIPS_FPU_EMU_INC_STATS(errors);
+ *fault_addr = va;
+ return SIGSEGV;
+ }
DITOREG(val, MIPSInst_FD(ir));
break;
@@ -714,10 +776,16 @@
MIPS_FPU_EMU_INC_STATS(stores);
DIFROMREG(val, MIPSInst_FS(ir));
- if (put_user(val, va)) {
+ if (!access_ok(VERIFY_WRITE, va, sizeof(u64))) {
MIPS_FPU_EMU_INC_STATS(errors);
+ *fault_addr = va;
return SIGBUS;
}
+ if (__put_user(val, va)) {
+ MIPS_FPU_EMU_INC_STATS(errors);
+ *fault_addr = va;
+ return SIGSEGV;
+ }
break;
case madd_d_op:
@@ -1242,7 +1310,7 @@
}
int fpu_emulator_cop1Handler(struct pt_regs *xcp, struct mips_fpu_struct *ctx,
- int has_fpu)
+ int has_fpu, void *__user *fault_addr)
{
unsigned long oldepc, prevepc;
mips_instruction insn;
@@ -1252,10 +1320,16 @@
do {
prevepc = xcp->cp0_epc;
- if (get_user(insn, (mips_instruction __user *) xcp->cp0_epc)) {
+ if (!access_ok(VERIFY_READ, xcp->cp0_epc, sizeof(mips_instruction))) {
MIPS_FPU_EMU_INC_STATS(errors);
+ *fault_addr = (mips_instruction __user *)xcp->cp0_epc;
return SIGBUS;
}
+ if (__get_user(insn, (mips_instruction __user *) xcp->cp0_epc)) {
+ MIPS_FPU_EMU_INC_STATS(errors);
+ *fault_addr = (mips_instruction __user *)xcp->cp0_epc;
+ return SIGSEGV;
+ }
if (insn == 0)
xcp->cp0_epc += 4; /* skip nops */
else {
@@ -1267,7 +1341,7 @@
*/
/* convert to ieee library modes */
ieee754_csr.rm = ieee_rm[ieee754_csr.rm];
- sig = cop1Emulate(xcp, ctx);
+ sig = cop1Emulate(xcp, ctx, fault_addr);
/* revert to mips rounding mode */
ieee754_csr.rm = mips_rm[ieee754_csr.rm];
}