os/doc
3
0
Fork 0
Code Issues Pull requests Projects Releases Wiki Activity
doc/website/static/security/patches/SA-18:07/lazyfpu-11.patch
Sergio Carlavilla Delgado 989d921f5d Migrate doc to Hugo/AsciiDoctor 
I'm very pleased to announce the release of
our new website and documentation using
the new toolchain with Hugo and AsciiDoctor.

To get more information about the new toolchain
please read the FreeBSD Documentation Project Primer[1],
Hugo docs[2] and AsciiDoctor docs[3].

Acknowledgment:
Benedict Reuschling <bcr@>
Glen Barber <gjb@>
Hiroki Sato <hrs@>
Li-Wen Hsu <lwhsu@>
Sean Chittenden <seanc@>
The FreeBSD Foundation

[1] https://docs.FreeBSD.org/en/books/fdp-primer/
[2] https://gohugo.io/documentation/
[3] https://docs.asciidoctor.org/home/

Approved by:    doceng, core
2021-01-26 00:31:29 +01:00

373 lines
9.8 KiB
Diff
Raw Blame History

--- sys/amd64/amd64/cpu_switch.S.orig
+++ sys/amd64/amd64/cpu_switch.S
@@ -105,10 +105,10 @@
/* have we used fp, and need a save? */
cmpq %rdi,PCPU(FPCURTHREAD)
- jne 3f
+ jne 2f
movq PCB_SAVEFPU(%r8),%r8
clts
- cmpl $0,use_xsave
+ cmpl $0,use_xsave(%rip)
jne 1f
fxsave (%r8)
jmp 2f
@@ -120,12 +120,7 @@
/* This is patched to xsaveopt if supported, see fpuinit_bsp1() */
xsave (%r8)
movq %rcx,%rdx
-2: smsw %ax
- orb $CR0_TS,%al
- lmsw %ax
- xorl %eax,%eax
- movq %rax,PCPU(FPCURTHREAD)
-3:
+2:
/* Save is done. Now fire up new thread. Leave old vmspace. */
movq %rsi,%r12
movq %rdi,%r13
@@ -212,6 +207,8 @@
movq PCB_RBX(%r8),%rbx
movq PCB_RIP(%r8),%rax
movq %rax,(%rsp)
+ movq PCPU(CURTHREAD),%rdi
+ call fpu_activate_sw
ret
/*
--- sys/amd64/amd64/fpu.c.orig
+++ sys/amd64/amd64/fpu.c
@@ -139,6 +139,11 @@
SYSCTL_INT(_hw, HW_FLOATINGPT, floatingpoint, CTLFLAG_RD,
SYSCTL_NULL_INT_PTR, 1, "Floating point instructions executed in hardware");
+int lazy_fpu_switch = 0;
+SYSCTL_INT(_hw, OID_AUTO, lazy_fpu_switch, CTLFLAG_RWTUN | CTLFLAG_NOFETCH,
+ &lazy_fpu_switch, 0,
+ "Lazily load FPU context after context switch");
+
int use_xsave; /* non-static for cpu_switch.S */
uint64_t xsave_mask; /* the same */
static uma_zone_t fpu_save_area_zone;
@@ -204,6 +209,7 @@
u_int cp[4];
uint64_t xsave_mask_user;
+ TUNABLE_INT_FETCH("hw.lazy_fpu_switch", &lazy_fpu_switch);
if ((cpu_feature2 & CPUID2_XSAVE) != 0) {
use_xsave = 1;
TUNABLE_INT_FETCH("hw.use_xsave", &use_xsave);
@@ -611,6 +617,45 @@
return (fpetable[(mxcsr & (~mxcsr >> 7)) & 0x3f]);
}
+static void
+restore_fpu_curthread(struct thread *td)
+{
+ struct pcb *pcb;
+
+ /*
+ * Record new context early in case frstor causes a trap.
+ */
+ PCPU_SET(fpcurthread, td);
+
+ stop_emulating();
+ fpu_clean_state();
+ pcb = td->td_pcb;
+
+ if ((pcb->pcb_flags & PCB_FPUINITDONE) == 0) {
+ /*
+ * This is the first time this thread has used the FPU or
+ * the PCB doesn't contain a clean FPU state. Explicitly
+ * load an initial state.
+ *
+ * We prefer to restore the state from the actual save
+ * area in PCB instead of directly loading from
+ * fpu_initialstate, to ignite the XSAVEOPT
+ * tracking engine.
+ */
+ bcopy(fpu_initialstate, pcb->pcb_save,
+ cpu_max_ext_state_size);
+ fpurestore(pcb->pcb_save);
+ if (pcb->pcb_initial_fpucw != __INITIAL_FPUCW__)
+ fldcw(pcb->pcb_initial_fpucw);
+ if (PCB_USER_FPU(pcb))
+ set_pcb_flags(pcb, PCB_FPUINITDONE |
+ PCB_USERFPUINITDONE);
+ else
+ set_pcb_flags(pcb, PCB_FPUINITDONE);
+ } else
+ fpurestore(pcb->pcb_save);
+}
+
/*
* Device Not Available (DNA, #NM) exception handler.
*
@@ -621,7 +666,9 @@
void
fpudna(void)
{
+ struct thread *td;
+ td = curthread;
/*
* This handler is entered with interrupts enabled, so context
* switches may occur before critical_enter() is executed. If
@@ -635,49 +682,38 @@
KASSERT((curpcb->pcb_flags & PCB_FPUNOSAVE) == 0,
("fpudna while in fpu_kern_enter(FPU_KERN_NOCTX)"));
- if (PCPU_GET(fpcurthread) == curthread) {
- printf("fpudna: fpcurthread == curthread\n");
+ if (__predict_false(PCPU_GET(fpcurthread) == td)) {
+ /*
+ * Some virtual machines seems to set %cr0.TS at
+ * arbitrary moments. Silently clear the TS bit
+ * regardless of the eager/lazy FPU context switch
+ * mode.
+ */
stop_emulating();
- critical_exit();
- return;
+ } else {
+ if (__predict_false(PCPU_GET(fpcurthread) != NULL)) {
+ panic(
+ "fpudna: fpcurthread = %p (%d), curthread = %p (%d)\n",
+ PCPU_GET(fpcurthread),
+ PCPU_GET(fpcurthread)->td_tid, td, td->td_tid);
+ }
+ restore_fpu_curthread(td);
}
- if (PCPU_GET(fpcurthread) != NULL) {
- panic("fpudna: fpcurthread = %p (%d), curthread = %p (%d)\n",
- PCPU_GET(fpcurthread), PCPU_GET(fpcurthread)->td_tid,
- curthread, curthread->td_tid);
- }
- stop_emulating();
- /*
- * Record new context early in case frstor causes a trap.
- */
- PCPU_SET(fpcurthread, curthread);
+ critical_exit();
+}
- fpu_clean_state();
+void fpu_activate_sw(struct thread *td); /* Called from the context switch */
+void
+fpu_activate_sw(struct thread *td)
+{
- if ((curpcb->pcb_flags & PCB_FPUINITDONE) == 0) {
- /*
- * This is the first time this thread has used the FPU or
- * the PCB doesn't contain a clean FPU state. Explicitly
- * load an initial state.
- *
- * We prefer to restore the state from the actual save
- * area in PCB instead of directly loading from
- * fpu_initialstate, to ignite the XSAVEOPT
- * tracking engine.
- */
- bcopy(fpu_initialstate, curpcb->pcb_save,
- cpu_max_ext_state_size);
- fpurestore(curpcb->pcb_save);
- if (curpcb->pcb_initial_fpucw != __INITIAL_FPUCW__)
- fldcw(curpcb->pcb_initial_fpucw);
- if (PCB_USER_FPU(curpcb))
- set_pcb_flags(curpcb,
- PCB_FPUINITDONE | PCB_USERFPUINITDONE);
- else
- set_pcb_flags(curpcb, PCB_FPUINITDONE);
- } else
- fpurestore(curpcb->pcb_save);
- critical_exit();
+ if (lazy_fpu_switch || (td->td_pflags & TDP_KTHREAD) != 0 ||
+ !PCB_USER_FPU(td->td_pcb)) {
+ PCPU_SET(fpcurthread, NULL);
+ start_emulating();
+ } else if (PCPU_GET(fpcurthread) != td) {
+ restore_fpu_curthread(td);
+ }
}
void
--- sys/i386/i386/swtch.s.orig
+++ sys/i386/i386/swtch.s
@@ -293,6 +293,12 @@
cpu_switch_load_gs:
mov PCB_GS(%edx),%gs
+ pushl %edx
+ pushl PCPU(CURTHREAD)
+ call npxswitch
+ popl %edx
+ popl %edx
+
/* Test if debug registers should be restored. */
testl $PCB_DBREGS,PCB_FLAGS(%edx)
jz 1f
--- sys/i386/isa/npx.c.orig
+++ sys/i386/isa/npx.c
@@ -191,6 +191,11 @@
SYSCTL_INT(_hw, HW_FLOATINGPT, floatingpoint, CTLFLAG_RD,
&hw_float, 0, "Floating point instructions executed in hardware");
+int lazy_fpu_switch = 0;
+SYSCTL_INT(_hw, OID_AUTO, lazy_fpu_switch, CTLFLAG_RWTUN | CTLFLAG_NOFETCH,
+ &lazy_fpu_switch, 0,
+ "Lazily load FPU context after context switch");
+
int use_xsave;
uint64_t xsave_mask;
static uma_zone_t fpu_save_area_zone;
@@ -327,6 +332,7 @@
u_int cp[4];
uint64_t xsave_mask_user;
+ TUNABLE_INT_FETCH("hw.lazy_fpu_switch", &lazy_fpu_switch);
if (cpu_fxsr && (cpu_feature2 & CPUID2_XSAVE) != 0) {
use_xsave = 1;
TUNABLE_INT_FETCH("hw.use_xsave", &use_xsave);
@@ -785,47 +791,20 @@
return (fpetable[(mxcsr & (~mxcsr >> 7)) & 0x3f]);
}
-/*
- * Implement device not available (DNA) exception
- *
- * It would be better to switch FP context here (if curthread != fpcurthread)
- * and not necessarily for every context switch, but it is too hard to
- * access foreign pcb's.
- */
-
-static int err_count = 0;
-
-int
-npxdna(void)
+static void
+restore_npx_curthread(struct thread *td, struct pcb *pcb)
{
- if (!hw_float)
- return (0);
- critical_enter();
- if (PCPU_GET(fpcurthread) == curthread) {
- printf("npxdna: fpcurthread == curthread %d times\n",
- ++err_count);
- stop_emulating();
- critical_exit();
- return (1);
- }
- if (PCPU_GET(fpcurthread) != NULL) {
- printf("npxdna: fpcurthread = %p (%d), curthread = %p (%d)\n",
- PCPU_GET(fpcurthread),
- PCPU_GET(fpcurthread)->td_proc->p_pid,
- curthread, curthread->td_proc->p_pid);
- panic("npxdna");
- }
- stop_emulating();
/*
* Record new context early in case frstor causes a trap.
*/
- PCPU_SET(fpcurthread, curthread);
+ PCPU_SET(fpcurthread, td);
+ stop_emulating();
if (cpu_fxsr)
fpu_clean_state();
- if ((curpcb->pcb_flags & PCB_NPXINITDONE) == 0) {
+ if ((pcb->pcb_flags & PCB_NPXINITDONE) == 0) {
/*
* This is the first time this thread has used the FPU or
* the PCB doesn't contain a clean FPU state. Explicitly
@@ -836,18 +815,54 @@
* npx_initialstate, to ignite the XSAVEOPT
* tracking engine.
*/
- bcopy(npx_initialstate, curpcb->pcb_save, cpu_max_ext_state_size);
- fpurstor(curpcb->pcb_save);
- if (curpcb->pcb_initial_npxcw != __INITIAL_NPXCW__)
- fldcw(curpcb->pcb_initial_npxcw);
- curpcb->pcb_flags |= PCB_NPXINITDONE;
- if (PCB_USER_FPU(curpcb))
- curpcb->pcb_flags |= PCB_NPXUSERINITDONE;
+ bcopy(npx_initialstate, pcb->pcb_save, cpu_max_ext_state_size);
+ fpurstor(pcb->pcb_save);
+ if (pcb->pcb_initial_npxcw != __INITIAL_NPXCW__)
+ fldcw(pcb->pcb_initial_npxcw);
+ pcb->pcb_flags |= PCB_NPXINITDONE;
+ if (PCB_USER_FPU(pcb))
+ pcb->pcb_flags |= PCB_NPXUSERINITDONE;
} else {
- fpurstor(curpcb->pcb_save);
+ fpurstor(pcb->pcb_save);
}
+}
+
+/*
+ * Implement device not available (DNA) exception
+ *
+ * It would be better to switch FP context here (if curthread != fpcurthread)
+ * and not necessarily for every context switch, but it is too hard to
+ * access foreign pcb's.
+ */
+int
+npxdna(void)
+{
+ struct thread *td;
+
+ if (!hw_float)
+ return (0);
+ td = curthread;
+ critical_enter();
+ if (__predict_false(PCPU_GET(fpcurthread) == td)) {
+ /*
+ * Some virtual machines seems to set %cr0.TS at
+ * arbitrary moments. Silently clear the TS bit
+ * regardless of the eager/lazy FPU context switch
+ * mode.
+ */
+ stop_emulating();
+ } else {
+ if (__predict_false(PCPU_GET(fpcurthread) != NULL)) {
+ printf(
+ "npxdna: fpcurthread = %p (%d), curthread = %p (%d)\n",
+ PCPU_GET(fpcurthread),
+ PCPU_GET(fpcurthread)->td_proc->p_pid,
+ td, td->td_proc->p_pid);
+ panic("npxdna");
+ }
+ restore_npx_curthread(td, td->td_pcb);
+ }
critical_exit();
-
return (1);
}
@@ -869,10 +884,22 @@
xsaveopt((char *)addr, xsave_mask);
else
fpusave(addr);
- start_emulating();
- PCPU_SET(fpcurthread, NULL);
}
+void npxswitch(struct thread *td, struct pcb *pcb);
+void
+npxswitch(struct thread *td, struct pcb *pcb)
+{
+
+ if (lazy_fpu_switch || (td->td_pflags & TDP_KTHREAD) != 0 ||
+ !PCB_USER_FPU(pcb)) {
+ start_emulating();
+ PCPU_SET(fpcurthread, NULL);
+ } else if (PCPU_GET(fpcurthread) != td) {
+ restore_npx_curthread(td, pcb);
+ }
+}
+
/*
* Unconditionally save the current co-processor state across suspend and
* resume.
Reference in a new issue View git blame Copy permalink