[PATCH 3.16 098/254] MIPS: Set `si_code' for SIGFPE signals sent from emulation too

3.16.55-rc1 review patch. If anyone has any objections, please let me know.

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From: "Maciej W. Rozycki" macro@linux-mips.org

commit 304acb717e5b67cf56f05bc5b21123758e1f7ea0 upstream.

Rework `process_fpemu_return' and move IEEE 754 exception interpretation there, from `do_fpe'. Record the cause bits set in FCSR before they are cleared and pass them through to `process_fpemu_return' so as to set `si_code' correctly too for SIGFPE signals sent from emulation rather than those issued by hardware with the FPE processor exception only.

For simplicity `mipsr2_decoder' assumes `*fcr31' has been preinitialised and only sets it to anything if an FPU instruction has been emulated, which in turn is the only case SIGFPE can be issued for here.

Signed-off-by: Maciej W. Rozycki macro@linux-mips.org Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/9705/ Signed-off-by: Ralf Baechle ralf@linux-mips.org [bwh: Backported to 3.16: - Drop changes in mips-r2-to-r6-emul and simulate_fp() - Adjust context] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- --- a/arch/mips/include/asm/fpu_emulator.h +++ b/arch/mips/include/asm/fpu_emulator.h @@ -65,7 +65,8 @@ extern int do_dsemulret(struct pt_regs * extern int fpu_emulator_cop1Handler(struct pt_regs *xcp, struct mips_fpu_struct *ctx, int has_fpu, void *__user *fault_addr); -int process_fpemu_return(int sig, void __user *fault_addr); +int process_fpemu_return(int sig, void __user *fault_addr, + unsigned long fcr31); int mm_isBranchInstr(struct pt_regs *regs, struct mm_decoded_insn dec_insn, unsigned long *contpc);

--- a/arch/mips/kernel/traps.c +++ b/arch/mips/kernel/traps.c @@ -707,29 +707,60 @@ asmlinkage void do_ov(struct pt_regs *re exception_exit(prev_state); }

-int process_fpemu_return(int sig, void __user *fault_addr) +int process_fpemu_return(int sig, void __user *fault_addr, unsigned long fcr31) { - if (sig == SIGSEGV || sig == SIGBUS) { - struct siginfo si = {0}; + struct siginfo si = { 0 }; + + switch (sig) { + case 0: + return 0; + + case SIGFPE: si.si_addr = fault_addr; si.si_signo = sig; - if (sig == SIGSEGV) { - down_read(&current->mm->mmap_sem); - if (find_vma(current->mm, (unsigned long)fault_addr)) - si.si_code = SEGV_ACCERR; - else - si.si_code = SEGV_MAPERR; - up_read(&current->mm->mmap_sem); - } else { - si.si_code = BUS_ADRERR; - } + /* + * Inexact can happen together with Overflow or Underflow. + * Respect the mask to deliver the correct exception. + */ + fcr31 &= (fcr31 & FPU_CSR_ALL_E) << + (ffs(FPU_CSR_ALL_X) - ffs(FPU_CSR_ALL_E)); + if (fcr31 & FPU_CSR_INV_X) + si.si_code = FPE_FLTINV; + else if (fcr31 & FPU_CSR_DIV_X) + si.si_code = FPE_FLTDIV; + else if (fcr31 & FPU_CSR_OVF_X) + si.si_code = FPE_FLTOVF; + else if (fcr31 & FPU_CSR_UDF_X) + si.si_code = FPE_FLTUND; + else if (fcr31 & FPU_CSR_INE_X) + si.si_code = FPE_FLTRES; + else + si.si_code = __SI_FAULT; + force_sig_info(sig, &si, current); + return 1; + + case SIGBUS: + si.si_addr = fault_addr; + si.si_signo = sig; + si.si_code = BUS_ADRERR; + force_sig_info(sig, &si, current); + return 1; + + case SIGSEGV: + si.si_addr = fault_addr; + si.si_signo = sig; + down_read(&current->mm->mmap_sem); + if (find_vma(current->mm, (unsigned long)fault_addr)) + si.si_code = SEGV_ACCERR; + else + si.si_code = SEGV_MAPERR; + up_read(&current->mm->mmap_sem); force_sig_info(sig, &si, current); return 1; - } else if (sig) { + + default: force_sig(sig, current); return 1; - } else { - return 0; } }

@@ -739,7 +770,8 @@ int process_fpemu_return(int sig, void _ asmlinkage void do_fpe(struct pt_regs *regs, unsigned long fcr31) { enum ctx_state prev_state; - siginfo_t info = {0}; + void __user *fault_addr; + int sig;

prev_state = exception_enter(); if (notify_die(DIE_FP, "FP exception", regs, 0, regs_to_trapnr(regs), @@ -753,9 +785,6 @@ asmlinkage void do_fpe(struct pt_regs *r die_if_kernel("FP exception in kernel code", regs);

if (fcr31 & FPU_CSR_UNI_X) { - int sig; - void __user *fault_addr = NULL; - /* * Unimplemented operation exception. If we've got the full * software emulator on-board, let's use it... @@ -772,6 +801,7 @@ asmlinkage void do_fpe(struct pt_regs *r /* Run the emulator */ sig = fpu_emulator_cop1Handler(regs, &current->thread.fpu, 1, &fault_addr); + fcr31 = current->thread.fpu.fcr31;

/* * We can't allow the emulated instruction to leave any of @@ -781,35 +811,13 @@ asmlinkage void do_fpe(struct pt_regs *r

/* Restore the hardware register state */ own_fpu(1); /* Using the FPU again. */ - - /* If something went wrong, signal */ - process_fpemu_return(sig, fault_addr); - - goto out; + } else { + sig = SIGFPE; + fault_addr = (void __user *) regs->cp0_epc; }

- /* - * Inexact can happen together with Overflow or Underflow. - * Respect the mask to deliver the correct exception. - */ - fcr31 &= (fcr31 & FPU_CSR_ALL_E) << - (ffs(FPU_CSR_ALL_X) - ffs(FPU_CSR_ALL_E)); - if (fcr31 & FPU_CSR_INV_X) - info.si_code = FPE_FLTINV; - else if (fcr31 & FPU_CSR_DIV_X) - info.si_code = FPE_FLTDIV; - else if (fcr31 & FPU_CSR_OVF_X) - info.si_code = FPE_FLTOVF; - else if (fcr31 & FPU_CSR_UDF_X) - info.si_code = FPE_FLTUND; - else if (fcr31 & FPU_CSR_INE_X) - info.si_code = FPE_FLTRES; - else - info.si_code = __SI_FAULT; - info.si_signo = SIGFPE; - info.si_errno = 0; - info.si_addr = (void __user *) regs->cp0_epc; - force_sig_info(SIGFPE, &info, current); + /* Send a signal if required. */ + process_fpemu_return(sig, fault_addr, fcr31);

out: exception_exit(prev_state); @@ -1210,10 +1218,13 @@ asmlinkage void do_cpu(struct pt_regs *r enum ctx_state prev_state; unsigned int __user *epc; unsigned long old_epc, old31; + void __user *fault_addr; unsigned int opcode; + unsigned long fcr31; unsigned int cpid; int status, err; unsigned long __maybe_unused flags; + int sig;

prev_state = exception_enter(); cpid = (regs->cp0_cause >> CAUSEB_CE) & 3; @@ -1286,22 +1297,22 @@ asmlinkage void do_cpu(struct pt_regs *r case 1: err = enable_restore_fp_context(0);

- if (!raw_cpu_has_fpu || err) { - int sig; - void __user *fault_addr = NULL; - sig = fpu_emulator_cop1Handler(regs, - &current->thread.fpu, - 0, &fault_addr); - - /* - * We can't allow the emulated instruction to leave - * any of the cause bits set in $fcr31. - */ - current->thread.fpu.fcr31 &= ~FPU_CSR_ALL_X; + if (raw_cpu_has_fpu && !err) + break;

- if (!process_fpemu_return(sig, fault_addr) && !err) - mt_ase_fp_affinity(); - } + sig = fpu_emulator_cop1Handler(regs, &current->thread.fpu, 0, + &fault_addr); + fcr31 = current->thread.fpu.fcr31; + + /* + * We can't allow the emulated instruction to leave + * any of the cause bits set in $fcr31. + */ + current->thread.fpu.fcr31 &= ~FPU_CSR_ALL_X; + + /* Send a signal if required. */ + if (!process_fpemu_return(sig, fault_addr, fcr31) && !err) + mt_ase_fp_affinity();

goto out;

--- a/arch/mips/kernel/unaligned.c +++ b/arch/mips/kernel/unaligned.c @@ -697,7 +697,7 @@ static void emulate_load_store_insn(stru own_fpu(1); /* Restore FPU state. */

/* Signal if something went wrong. */ - process_fpemu_return(res, fault_addr); + process_fpemu_return(res, fault_addr, 0);

if (res == 0) break; @@ -1129,7 +1129,7 @@ fpu_emul: own_fpu(1); /* restore FPU state */

/* If something went wrong, signal */ - process_fpemu_return(res, fault_addr); + process_fpemu_return(res, fault_addr, 0);

if (res == 0) goto success;