From e1b708897ea547f25fbc5fc1f73bb2b0738c5757 Mon Sep 17 00:00:00 2001 From: jhb Date: Thu, 5 Mar 2009 19:42:11 +0000 Subject: A better fix for handling different FPU initial control words for different ABIs: - Store the FPU initial control word in the pcb for each thread. - When first using the FPU, load the initial control word after restoring the clean state if it is not the standard control word. - Provide a correct control word for Linux/i386 binaries under FreeBSD/amd64. - Adjust the control word returned for fpugetregs()/npxgetregs() when a thread hasn't used the FPU yet to reflect the real initial control word for the current ABI. - The Linux/i386 ABI for FreeBSD/i386 now properly sets the right control word instead of trashing whatever the current state of the FPU is. Reviewed by: bde --- sys/i386/i386/machdep.c | 3 ++- sys/i386/include/pcb.h | 1 + sys/i386/isa/npx.c | 11 +++++++++++ sys/i386/linux/linux_sysvec.c | 10 +++------- 4 files changed, 17 insertions(+), 8 deletions(-) (limited to 'sys/i386') diff --git a/sys/i386/i386/machdep.c b/sys/i386/i386/machdep.c index 803d8d1..e10217a 100644 --- a/sys/i386/i386/machdep.c +++ b/sys/i386/i386/machdep.c @@ -1362,7 +1362,7 @@ SYSCTL_PROC(_machdep, OID_AUTO, idle, CTLTYPE_STRING | CTLFLAG_RW, 0, 0, idle_sysctl, "A", "currently selected idle function"); /* - * Clear registers on exec + * Reset registers to default values on exec. */ void exec_setregs(td, entry, stack, ps_strings) @@ -1427,6 +1427,7 @@ exec_setregs(td, entry, stack, ps_strings) * emulators don't provide an entry point for initialization. */ td->td_pcb->pcb_flags &= ~FP_SOFTFP; + pcb->pcb_initial_npxcw = __INITIAL_NPXCW__; /* * Drop the FP state if we hold it, so that the process gets a diff --git a/sys/i386/include/pcb.h b/sys/i386/include/pcb.h index ff6ff5a..17c8486 100644 --- a/sys/i386/include/pcb.h +++ b/sys/i386/include/pcb.h @@ -61,6 +61,7 @@ struct pcb { int pcb_dr7; union savefpu pcb_save; + uint16_t pcb_initial_npxcw; u_int pcb_flags; #define FP_SOFTFP 0x01 /* process using software fltng pnt emulator */ #define PCB_DBREGS 0x02 /* process using debug registers */ diff --git a/sys/i386/isa/npx.c b/sys/i386/isa/npx.c index aaf2eb5..a4f5b34 100644 --- a/sys/i386/isa/npx.c +++ b/sys/i386/isa/npx.c @@ -141,11 +141,19 @@ void stop_emulating(void); (cpu_fxsr ? \ (thread)->td_pcb->pcb_save.sv_xmm.sv_env.en_sw : \ (thread)->td_pcb->pcb_save.sv_87.sv_env.en_sw) +#define SET_FPU_CW(savefpu, value) do { \ + if (cpu_fxsr) \ + (savefpu)->sv_xmm.sv_env.en_cw = (value); \ + else \ + (savefpu)->sv_87.sv_env.en_cw = (value); \ +} while (0) #else /* CPU_ENABLE_SSE */ #define GET_FPU_CW(thread) \ (thread->td_pcb->pcb_save.sv_87.sv_env.en_cw) #define GET_FPU_SW(thread) \ (thread->td_pcb->pcb_save.sv_87.sv_env.en_sw) +#define SET_FPU_CW(savefpu, value) \ + (savefpu)->sv_87.sv_env.en_cw = (value) #endif /* CPU_ENABLE_SSE */ typedef u_char bool_t; @@ -793,6 +801,8 @@ npxdna(void) * load sanitized registers. */ fpurstor(&npx_cleanstate); + if (pcb->pcb_initial_npxcw != __INITIAL_NPXCW__) + fldcw(&pcb->pcb_initial_npxcw); pcb->pcb_flags |= PCB_NPXINITDONE; } else { /* @@ -891,6 +901,7 @@ npxgetregs(td, addr) if ((td->td_pcb->pcb_flags & PCB_NPXINITDONE) == 0) { bcopy(&npx_cleanstate, addr, sizeof(npx_cleanstate)); + SET_FPU_CW(addr, td->td_pcb->pcb_initial_npxcw); return (_MC_FPOWNED_NONE); } s = intr_disable(); diff --git a/sys/i386/linux/linux_sysvec.c b/sys/i386/linux/linux_sysvec.c index c98fe14..4efd496 100644 --- a/sys/i386/linux/linux_sysvec.c +++ b/sys/i386/linux/linux_sysvec.c @@ -89,9 +89,6 @@ MALLOC_DEFINE(M_LINUX, "linux", "Linux mode structures"); #define LINUX_SYS_linux_rt_sendsig 0 #define LINUX_SYS_linux_sendsig 0 -#define fldcw(addr) __asm("fldcw %0" : : "m" (*(addr))) -#define __LINUX_NPXCW__ 0x37f - extern char linux_sigcode[]; extern int linux_szsigcode; @@ -930,16 +927,15 @@ static void exec_linux_setregs(struct thread *td, u_long entry, u_long stack, u_long ps_strings) { - static const u_short control = __LINUX_NPXCW__; struct pcb *pcb = td->td_pcb; exec_setregs(td, entry, stack, ps_strings); /* Linux sets %gs to 0, we default to _udatasel */ - pcb->pcb_gs = 0; load_gs(0); + pcb->pcb_gs = 0; + load_gs(0); - /* Linux sets the i387 to extended precision. */ - fldcw(&control); + pcb->pcb_initial_npxcw = __LINUX_NPXCW__; } static void -- cgit v1.1