From 456d3d42460c1fc20ba0d27442443fcd63aaac35 Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Fri, 25 May 2012 00:31:56 -0700 Subject: [PATCH] sparc64: Fix several bugs in quad floating point emulation. UltraSPARC-T2 and later do not use the fp_exception_other trap and do not set the floating point trap type field in the %fsr at all when you try to execute an unimplemented FPU operation. Instead, it uses the illegal_instruction trap and it leaves the floating point trap type field clear. So we should not validate the %fsr trap type field when do_mathemu() is invoked from the illegal instruction handler. Also, the floating point trap type field is 3 bits, not 4 bits. Signed-off-by: David S. Miller --- arch/sparc/kernel/traps_64.c | 12 +++++++----- arch/sparc/math-emu/math_64.c | 20 ++++++++++++++------ 2 files changed, 21 insertions(+), 11 deletions(-) diff --git a/arch/sparc/kernel/traps_64.c b/arch/sparc/kernel/traps_64.c index c72fdf55e1c1..3b05e6697710 100644 --- a/arch/sparc/kernel/traps_64.c +++ b/arch/sparc/kernel/traps_64.c @@ -2054,7 +2054,7 @@ void do_fpieee(struct pt_regs *regs) do_fpe_common(regs); } -extern int do_mathemu(struct pt_regs *, struct fpustate *); +extern int do_mathemu(struct pt_regs *, struct fpustate *, bool); void do_fpother(struct pt_regs *regs) { @@ -2068,7 +2068,7 @@ void do_fpother(struct pt_regs *regs) switch ((current_thread_info()->xfsr[0] & 0x1c000)) { case (2 << 14): /* unfinished_FPop */ case (3 << 14): /* unimplemented_FPop */ - ret = do_mathemu(regs, f); + ret = do_mathemu(regs, f, false); break; } if (ret) @@ -2308,10 +2308,12 @@ void do_illegal_instruction(struct pt_regs *regs) } else { struct fpustate *f = FPUSTATE; - /* XXX maybe verify XFSR bits like - * XXX do_fpother() does? + /* On UltraSPARC T2 and later, FPU insns which + * are not implemented in HW signal an illegal + * instruction trap and do not set the FP Trap + * Trap in the %fsr to unimplemented_FPop. */ - if (do_mathemu(regs, f)) + if (do_mathemu(regs, f, true)) return; } } diff --git a/arch/sparc/math-emu/math_64.c b/arch/sparc/math-emu/math_64.c index 2bbe2f28ad23..1704068da928 100644 --- a/arch/sparc/math-emu/math_64.c +++ b/arch/sparc/math-emu/math_64.c @@ -163,7 +163,7 @@ typedef union { u64 q[2]; } *argp; -int do_mathemu(struct pt_regs *regs, struct fpustate *f) +int do_mathemu(struct pt_regs *regs, struct fpustate *f, bool illegal_insn_trap) { unsigned long pc = regs->tpc; unsigned long tstate = regs->tstate; @@ -218,7 +218,7 @@ int do_mathemu(struct pt_regs *regs, struct fpustate *f) case FSQRTS: { unsigned long x = current_thread_info()->xfsr[0]; - x = (x >> 14) & 0xf; + x = (x >> 14) & 0x7; TYPE(x,1,1,1,1,0,0); break; } @@ -226,7 +226,7 @@ int do_mathemu(struct pt_regs *regs, struct fpustate *f) case FSQRTD: { unsigned long x = current_thread_info()->xfsr[0]; - x = (x >> 14) & 0xf; + x = (x >> 14) & 0x7; TYPE(x,2,1,2,1,0,0); break; } @@ -357,9 +357,17 @@ int do_mathemu(struct pt_regs *regs, struct fpustate *f) if (type) { argp rs1 = NULL, rs2 = NULL, rd = NULL; - freg = (current_thread_info()->xfsr[0] >> 14) & 0xf; - if (freg != (type >> 9)) - goto err; + /* Starting with UltraSPARC-T2, the cpu does not set the FP Trap + * Type field in the %fsr to unimplemented_FPop. Nor does it + * use the fp_exception_other trap. Instead it signals an + * illegal instruction and leaves the FP trap type field of + * the %fsr unchanged. + */ + if (!illegal_insn_trap) { + int ftt = (current_thread_info()->xfsr[0] >> 14) & 0x7; + if (ftt != (type >> 9)) + goto err; + } current_thread_info()->xfsr[0] &= ~0x1c000; freg = ((insn >> 14) & 0x1f); switch (type & 0x3) { -- 2.39.2