x86/paravirt: split sysret and sysexit
Don't conflate sysret and sysexit; they're different instructions with
different semantics, and may be in use at the same time (at least
within the same kernel, depending on whether its an Intel or AMD
system).
sysexit - just return to userspace, does no register restoration of
any kind; must explicitly atomically enable interrupts.
sysret - reloads flags from r11, so no need to explicitly enable
interrupts on 64-bit, responsible for restoring usermode %gs
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citirx.com>
Cc: xen-devel <xen-devel@lists.xensource.com>
Cc: Stephen Tweedie <sct@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/kernel/asm-offsets_32.c b/arch/x86/kernel/asm-offsets_32.c
index 9258808..6649d09 100644
--- a/arch/x86/kernel/asm-offsets_32.c
+++ b/arch/x86/kernel/asm-offsets_32.c
@@ -111,7 +111,7 @@
OFFSET(PV_IRQ_irq_disable, pv_irq_ops, irq_disable);
OFFSET(PV_IRQ_irq_enable, pv_irq_ops, irq_enable);
OFFSET(PV_CPU_iret, pv_cpu_ops, iret);
- OFFSET(PV_CPU_irq_enable_syscall_ret, pv_cpu_ops, irq_enable_syscall_ret);
+ OFFSET(PV_CPU_irq_enable_sysexit, pv_cpu_ops, irq_enable_sysexit);
OFFSET(PV_CPU_read_cr0, pv_cpu_ops, read_cr0);
#endif
diff --git a/arch/x86/kernel/asm-offsets_64.c b/arch/x86/kernel/asm-offsets_64.c
index f126c05..27ac2de 100644
--- a/arch/x86/kernel/asm-offsets_64.c
+++ b/arch/x86/kernel/asm-offsets_64.c
@@ -62,7 +62,7 @@
OFFSET(PV_IRQ_irq_disable, pv_irq_ops, irq_disable);
OFFSET(PV_IRQ_irq_enable, pv_irq_ops, irq_enable);
OFFSET(PV_CPU_iret, pv_cpu_ops, iret);
- OFFSET(PV_CPU_irq_enable_syscall_ret, pv_cpu_ops, irq_enable_syscall_ret);
+ OFFSET(PV_CPU_usersp_sysret, pv_cpu_ops, usersp_sysret);
OFFSET(PV_CPU_swapgs, pv_cpu_ops, swapgs);
OFFSET(PV_MMU_read_cr2, pv_mmu_ops, read_cr2);
#endif
diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index 159a1c7..53393c3 100644
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -58,7 +58,7 @@
* for paravirtualization. The following will never clobber any registers:
* INTERRUPT_RETURN (aka. "iret")
* GET_CR0_INTO_EAX (aka. "movl %cr0, %eax")
- * ENABLE_INTERRUPTS_SYSCALL_RET (aka "sti; sysexit").
+ * ENABLE_INTERRUPTS_SYSEXIT (aka "sti; sysexit").
*
* For DISABLE_INTERRUPTS/ENABLE_INTERRUPTS (aka "cli"/"sti"), you must
* specify what registers can be overwritten (CLBR_NONE, CLBR_EAX/EDX/ECX/ANY).
@@ -349,7 +349,7 @@
xorl %ebp,%ebp
TRACE_IRQS_ON
1: mov PT_FS(%esp), %fs
- ENABLE_INTERRUPTS_SYSCALL_RET
+ ENABLE_INTERRUPTS_SYSEXIT
CFI_ENDPROC
.pushsection .fixup,"ax"
2: movl $0,PT_FS(%esp)
@@ -874,10 +874,10 @@
.previous
END(native_iret)
-ENTRY(native_irq_enable_syscall_ret)
+ENTRY(native_irq_enable_sysexit)
sti
sysexit
-END(native_irq_enable_syscall_ret)
+END(native_irq_enable_sysexit)
#endif
KPROBE_ENTRY(int3)
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 6d11014..0056bc4 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -59,7 +59,7 @@
#endif
#ifdef CONFIG_PARAVIRT
-ENTRY(native_irq_enable_syscall_ret)
+ENTRY(native_usersp_sysret)
movq %gs:pda_oldrsp,%rsp
swapgs
sysretq
@@ -275,7 +275,7 @@
CFI_REGISTER rip,rcx
RESTORE_ARGS 0,-ARG_SKIP,1
/*CFI_REGISTER rflags,r11*/
- ENABLE_INTERRUPTS_SYSCALL_RET
+ USERSP_SYSRET
CFI_RESTORE_STATE
/* Handle reschedules */
diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
index 78c9a1b..565ee7a 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -140,7 +140,8 @@
/* If the operation is a nop, then nop the callsite */
ret = paravirt_patch_nop();
else if (type == PARAVIRT_PATCH(pv_cpu_ops.iret) ||
- type == PARAVIRT_PATCH(pv_cpu_ops.irq_enable_syscall_ret))
+ type == PARAVIRT_PATCH(pv_cpu_ops.irq_enable_sysexit) ||
+ type == PARAVIRT_PATCH(pv_cpu_ops.usersp_sysret))
/* If operation requires a jmp, then jmp */
ret = paravirt_patch_jmp(insnbuf, opfunc, addr, len);
else
@@ -191,7 +192,8 @@
/* These are in entry.S */
extern void native_iret(void);
-extern void native_irq_enable_syscall_ret(void);
+extern void native_irq_enable_sysexit(void);
+extern void native_usersp_sysret(void);
static int __init print_banner(void)
{
@@ -327,7 +329,11 @@
.write_idt_entry = native_write_idt_entry,
.load_sp0 = native_load_sp0,
- .irq_enable_syscall_ret = native_irq_enable_syscall_ret,
+#ifdef CONFIG_X86_32
+ .irq_enable_sysexit = native_irq_enable_sysexit,
+#else
+ .usersp_sysret = native_usersp_sysret,
+#endif
.iret = native_iret,
.swapgs = native_swapgs,
diff --git a/arch/x86/kernel/paravirt_patch_32.c b/arch/x86/kernel/paravirt_patch_32.c
index 82fc5fc..5826221 100644
--- a/arch/x86/kernel/paravirt_patch_32.c
+++ b/arch/x86/kernel/paravirt_patch_32.c
@@ -5,7 +5,7 @@
DEF_NATIVE(pv_irq_ops, restore_fl, "push %eax; popf");
DEF_NATIVE(pv_irq_ops, save_fl, "pushf; pop %eax");
DEF_NATIVE(pv_cpu_ops, iret, "iret");
-DEF_NATIVE(pv_cpu_ops, irq_enable_syscall_ret, "sti; sysexit");
+DEF_NATIVE(pv_cpu_ops, irq_enable_sysexit, "sti; sysexit");
DEF_NATIVE(pv_mmu_ops, read_cr2, "mov %cr2, %eax");
DEF_NATIVE(pv_mmu_ops, write_cr3, "mov %eax, %cr3");
DEF_NATIVE(pv_mmu_ops, read_cr3, "mov %cr3, %eax");
@@ -29,7 +29,7 @@
PATCH_SITE(pv_irq_ops, restore_fl);
PATCH_SITE(pv_irq_ops, save_fl);
PATCH_SITE(pv_cpu_ops, iret);
- PATCH_SITE(pv_cpu_ops, irq_enable_syscall_ret);
+ PATCH_SITE(pv_cpu_ops, irq_enable_sysexit);
PATCH_SITE(pv_mmu_ops, read_cr2);
PATCH_SITE(pv_mmu_ops, read_cr3);
PATCH_SITE(pv_mmu_ops, write_cr3);
diff --git a/arch/x86/kernel/paravirt_patch_64.c b/arch/x86/kernel/paravirt_patch_64.c
index 7d904e1..4a17055 100644
--- a/arch/x86/kernel/paravirt_patch_64.c
+++ b/arch/x86/kernel/paravirt_patch_64.c
@@ -15,7 +15,7 @@
DEF_NATIVE(pv_cpu_ops, wbinvd, "wbinvd");
/* the three commands give us more control to how to return from a syscall */
-DEF_NATIVE(pv_cpu_ops, irq_enable_syscall_ret, "movq %gs:" __stringify(pda_oldrsp) ", %rsp; swapgs; sysretq;");
+DEF_NATIVE(pv_cpu_ops, usersp_sysret, "movq %gs:" __stringify(pda_oldrsp) ", %rsp; swapgs; sysretq;");
DEF_NATIVE(pv_cpu_ops, swapgs, "swapgs");
unsigned native_patch(u8 type, u16 clobbers, void *ibuf,
@@ -35,7 +35,7 @@
PATCH_SITE(pv_irq_ops, irq_enable);
PATCH_SITE(pv_irq_ops, irq_disable);
PATCH_SITE(pv_cpu_ops, iret);
- PATCH_SITE(pv_cpu_ops, irq_enable_syscall_ret);
+ PATCH_SITE(pv_cpu_ops, usersp_sysret);
PATCH_SITE(pv_cpu_ops, swapgs);
PATCH_SITE(pv_mmu_ops, read_cr2);
PATCH_SITE(pv_mmu_ops, read_cr3);
diff --git a/arch/x86/kernel/vmi_32.c b/arch/x86/kernel/vmi_32.c
index 956f389..946bf13 100644
--- a/arch/x86/kernel/vmi_32.c
+++ b/arch/x86/kernel/vmi_32.c
@@ -151,7 +151,7 @@
insns, ip);
case PARAVIRT_PATCH(pv_cpu_ops.iret):
return patch_internal(VMI_CALL_IRET, len, insns, ip);
- case PARAVIRT_PATCH(pv_cpu_ops.irq_enable_syscall_ret):
+ case PARAVIRT_PATCH(pv_cpu_ops.irq_enable_sysexit):
return patch_internal(VMI_CALL_SYSEXIT, len, insns, ip);
default:
break;
@@ -896,7 +896,7 @@
* the backend. They are performance critical anyway, so requiring
* a patch is not a big problem.
*/
- pv_cpu_ops.irq_enable_syscall_ret = (void *)0xfeedbab0;
+ pv_cpu_ops.irq_enable_sysexit = (void *)0xfeedbab0;
pv_cpu_ops.iret = (void *)0xbadbab0;
#ifdef CONFIG_SMP
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index d62f14e..119c88f 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1089,7 +1089,7 @@
.read_pmc = native_read_pmc,
.iret = xen_iret,
- .irq_enable_syscall_ret = xen_sysexit,
+ .irq_enable_sysexit = xen_sysexit,
.load_tr_desc = paravirt_nop,
.set_ldt = xen_set_ldt,
diff --git a/include/asm-x86/irqflags.h b/include/asm-x86/irqflags.h
index c242527..99ee525 100644
--- a/include/asm-x86/irqflags.h
+++ b/include/asm-x86/irqflags.h
@@ -112,13 +112,13 @@
#ifdef CONFIG_X86_64
#define INTERRUPT_RETURN iretq
-#define ENABLE_INTERRUPTS_SYSCALL_RET \
+#define USERSP_SYSRET \
movq %gs:pda_oldrsp, %rsp; \
swapgs; \
sysretq;
#else
#define INTERRUPT_RETURN iret
-#define ENABLE_INTERRUPTS_SYSCALL_RET sti; sysexit
+#define ENABLE_INTERRUPTS_SYSEXIT sti; sysexit
#define GET_CR0_INTO_EAX movl %cr0, %eax
#endif
diff --git a/include/asm-x86/paravirt.h b/include/asm-x86/paravirt.h
index 82cdcde..2668903 100644
--- a/include/asm-x86/paravirt.h
+++ b/include/asm-x86/paravirt.h
@@ -141,8 +141,9 @@
u64 (*read_pmc)(int counter);
unsigned long long (*read_tscp)(unsigned int *aux);
- /* These two are jmp to, not actually called. */
- void (*irq_enable_syscall_ret)(void);
+ /* These three are jmp to, not actually called. */
+ void (*irq_enable_sysexit)(void);
+ void (*usersp_sysret)(void);
void (*iret)(void);
void (*swapgs)(void);
@@ -1480,10 +1481,10 @@
call PARA_INDIRECT(pv_irq_ops+PV_IRQ_irq_enable); \
PV_RESTORE_REGS;)
-#define ENABLE_INTERRUPTS_SYSCALL_RET \
- PARA_SITE(PARA_PATCH(pv_cpu_ops, PV_CPU_irq_enable_syscall_ret),\
+#define ENABLE_INTERRUPTS_SYSEXIT \
+ PARA_SITE(PARA_PATCH(pv_cpu_ops, PV_CPU_irq_enable_sysexit), \
CLBR_NONE, \
- jmp PARA_INDIRECT(pv_cpu_ops+PV_CPU_irq_enable_syscall_ret))
+ jmp PARA_INDIRECT(pv_cpu_ops+PV_CPU_irq_enable_sysexit))
#ifdef CONFIG_X86_32
@@ -1504,6 +1505,10 @@
movq %rax, %rcx; \
xorq %rax, %rax;
+#define USERSP_SYSRET \
+ PARA_SITE(PARA_PATCH(pv_cpu_ops, PV_CPU_usersp_sysret), \
+ CLBR_NONE, \
+ jmp PARA_INDIRECT(pv_cpu_ops+PV_CPU_usersp_sysret))
#endif
#endif /* __ASSEMBLY__ */