[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [PATCH v9 8/9] x86emul: support FLDENV and FRSTOR
While the Intel SDM claims that FRSTOR itself may raise #MF upon completion, this was confirmed by Intel to be a doc error which will be corrected in due course; behavior is like FLDENV, and like old hard copy manuals describe it. Re-arrange a switch() statement's case label order to allow for fall-through from FLDENV handling to FNSTENV's. Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx> --- v9: Refine description. Re-base over changes to earlier patch. Add comments. v7: New. --- a/tools/tests/x86_emulator/test_x86_emulator.c +++ b/tools/tests/x86_emulator/test_x86_emulator.c @@ -2442,6 +2442,27 @@ int main(int argc, char **argv) else printf("skipped\n"); + printf("%-40s", "Testing fldenv 8(%edx)..."); + if ( stack_exec && cpu_has_fpu ) + { + asm volatile ( "fnstenv %0\n\t" + "fninit" + : "=m" (res[2]) :: "memory" ); + zap_fpsel(&res[2], true); + instr[0] = 0xd9; instr[1] = 0x62; instr[2] = 0x08; + regs.eip = (unsigned long)&instr[0]; + regs.edx = (unsigned long)res; + rc = x86_emulate(&ctxt, &emulops); + asm volatile ( "fnstenv %0" : "=m" (res[9]) :: "memory" ); + if ( (rc != X86EMUL_OKAY) || + memcmp(res + 2, res + 9, 28) || + (regs.eip != (unsigned long)&instr[3]) ) + goto fail; + printf("okay\n"); + } + else + printf("skipped\n"); + printf("%-40s", "Testing 16-bit fnsave (%ecx)..."); if ( stack_exec && cpu_has_fpu ) { @@ -2468,6 +2489,31 @@ int main(int argc, char **argv) goto fail; printf("okay\n"); } + else + printf("skipped\n"); + + printf("%-40s", "Testing frstor (%edx)..."); + if ( stack_exec && cpu_has_fpu ) + { + const uint16_t seven = 7; + + asm volatile ( "fninit\n\t" + "fld1\n\t" + "fidivs %1\n\t" + "fnsave %0\n\t" + : "=&m" (res[0]) : "m" (seven) : "memory" ); + zap_fpsel(&res[0], true); + instr[0] = 0xdd; instr[1] = 0x22; + regs.eip = (unsigned long)&instr[0]; + regs.edx = (unsigned long)res; + rc = x86_emulate(&ctxt, &emulops); + asm volatile ( "fnsave %0" : "=m" (res[27]) :: "memory" ); + if ( (rc != X86EMUL_OKAY) || + memcmp(res, res + 27, 108) || + (regs.eip != (unsigned long)&instr[2]) ) + goto fail; + printf("okay\n"); + } else printf("skipped\n"); --- a/xen/arch/x86/x86_emulate/x86_emulate.c +++ b/xen/arch/x86/x86_emulate/x86_emulate.c @@ -857,6 +857,7 @@ struct x86_emulate_state { blk_NONE, blk_enqcmd, #ifndef X86EMUL_NO_FPU + blk_fld, /* FLDENV, FRSTOR */ blk_fst, /* FNSTENV, FNSAVE */ #endif blk_movdir, @@ -4948,22 +4949,15 @@ x86_emulate( dst.bytes = 4; emulate_fpu_insn_memdst(b, modrm_reg & 7, dst.val); break; - case 4: /* fldenv - TODO */ - state->fpu_ctrl = true; - goto unimplemented_insn; - case 5: /* fldcw m2byte */ - state->fpu_ctrl = true; - fpu_memsrc16: - if ( (rc = ops->read(ea.mem.seg, ea.mem.off, &src.val, - 2, ctxt)) != X86EMUL_OKAY ) - goto done; - emulate_fpu_insn_memsrc(b, modrm_reg & 7, src.val); - break; + case 4: /* fldenv */ + /* Raise #MF now if there are pending unmasked exceptions. */ + emulate_fpu_insn_stub(0xd9, 0xd0 /* fnop */); + /* fall through */ case 6: /* fnstenv */ fail_if(!ops->blk); - state->blk = blk_fst; + state->blk = modrm_reg & 2 ? blk_fst : blk_fld; /* - * REX is meaningless for this insn by this point - (ab)use + * REX is meaningless for these insns by this point - (ab)use * the field to communicate real vs protected mode to ->blk(). */ /*state->*/rex_prefix = in_protmode(ctxt, ops); @@ -4975,6 +4969,14 @@ x86_emulate( goto done; state->fpu_ctrl = true; break; + case 5: /* fldcw m2byte */ + state->fpu_ctrl = true; + fpu_memsrc16: + if ( (rc = ops->read(ea.mem.seg, ea.mem.off, &src.val, + 2, ctxt)) != X86EMUL_OKAY ) + goto done; + emulate_fpu_insn_memsrc(b, modrm_reg & 7, src.val); + break; case 7: /* fnstcw m2byte */ state->fpu_ctrl = true; fpu_memdst16: @@ -5127,14 +5129,15 @@ x86_emulate( dst.bytes = 8; emulate_fpu_insn_memdst(b, modrm_reg & 7, dst.val); break; - case 4: /* frstor - TODO */ - state->fpu_ctrl = true; - goto unimplemented_insn; + case 4: /* frstor */ + /* Raise #MF now if there are pending unmasked exceptions. */ + emulate_fpu_insn_stub(0xd9, 0xd0 /* fnop */); + /* fall through */ case 6: /* fnsave */ fail_if(!ops->blk); - state->blk = blk_fst; + state->blk = modrm_reg & 2 ? blk_fst : blk_fld; /* - * REX is meaningless for this insn by this point - (ab)use + * REX is meaningless for these insns by this point - (ab)use * the field to communicate real vs protected mode to ->blk(). */ /*state->*/rex_prefix = in_protmode(ctxt, ops); @@ -11664,6 +11667,92 @@ int x86_emul_blk( #ifndef X86EMUL_NO_FPU + case blk_fld: + ASSERT(!data); + + /* state->rex_prefix carries CR0.PE && !EFLAGS.VM setting */ + switch ( bytes ) + { + case sizeof(fpstate.env): /* 32-bit FLDENV */ + case sizeof(fpstate): /* 32-bit FRSTOR */ + memcpy(&fpstate.env, ptr, sizeof(fpstate.env)); + if ( !state->rex_prefix ) + { + /* Convert 32-bit real/vm86 to 32-bit prot format. */ + unsigned int fip = fpstate.env.mode.real.fip_lo + + (fpstate.env.mode.real.fip_hi << 16); + unsigned int fdp = fpstate.env.mode.real.fdp_lo + + (fpstate.env.mode.real.fdp_hi << 16); + unsigned int fop = fpstate.env.mode.real.fop; + + fpstate.env.mode.prot.fip = fip & 0xf; + fpstate.env.mode.prot.fcs = fip >> 4; + fpstate.env.mode.prot.fop = fop; + fpstate.env.mode.prot.fdp = fdp & 0xf; + fpstate.env.mode.prot.fds = fdp >> 4; + } + + if ( bytes == sizeof(fpstate.env) ) + ptr = NULL; + else + ptr += sizeof(fpstate.env); + break; + + case sizeof(struct x87_env16): /* 16-bit FLDENV */ + case sizeof(struct x87_env16) + sizeof(fpstate.freg): /* 16-bit FRSTOR */ + { + const struct x87_env16 *env = ptr; + + fpstate.env.fcw = env->fcw; + fpstate.env.fsw = env->fsw; + fpstate.env.ftw = env->ftw; + + if ( state->rex_prefix ) + { + /* Convert 16-bit prot to 32-bit prot format. */ + fpstate.env.mode.prot.fip = env->mode.prot.fip; + fpstate.env.mode.prot.fcs = env->mode.prot.fcs; + fpstate.env.mode.prot.fdp = env->mode.prot.fdp; + fpstate.env.mode.prot.fds = env->mode.prot.fds; + fpstate.env.mode.prot.fop = 0; /* unknown */ + } + else + { + /* Convert 16-bit real/vm86 to 32-bit prot format. */ + unsigned int fip = env->mode.real.fip_lo + + (env->mode.real.fip_hi << 16); + unsigned int fdp = env->mode.real.fdp_lo + + (env->mode.real.fdp_hi << 16); + unsigned int fop = env->mode.real.fop; + + fpstate.env.mode.prot.fip = fip & 0xf; + fpstate.env.mode.prot.fcs = fip >> 4; + fpstate.env.mode.prot.fop = fop; + fpstate.env.mode.prot.fdp = fdp & 0xf; + fpstate.env.mode.prot.fds = fdp >> 4; + } + + if ( bytes == sizeof(*env) ) + ptr = NULL; + else + ptr += sizeof(*env); + break; + } + + default: + ASSERT_UNREACHABLE(); + return X86EMUL_UNHANDLEABLE; + } + + if ( ptr ) + { + memcpy(fpstate.freg, ptr, sizeof(fpstate.freg)); + asm volatile ( "frstor %0" :: "m" (fpstate) ); + } + else + asm volatile ( "fldenv %0" :: "m" (fpstate.env) ); + break; + case blk_fst: ASSERT(!data);
|
Lists.xenproject.org is hosted with RackSpace, monitoring our |