[Xen-devel] [PATCH 31 of 36] x86_64 pvops: don't restore user rsp within sysret

[Jeremy Fitzhardinge <jeremy@xxxxxxxx>]

There's no need to combine restoring the user rsp within the sysret
pvop, so split it out.  This makes the pvop's semantics closer to the
machine instruction.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>
---
 arch/x86/kernel/asm-offsets_64.c    |    2 +-
 arch/x86/kernel/entry_64.S          |    6 +++---
 arch/x86/kernel/paravirt.c          |    6 +++---
 arch/x86/kernel/paravirt_patch_64.c |    4 ++--
 include/asm-x86/irqflags.h          |    3 +--
 include/asm-x86/paravirt.h          |    8 ++++----
 6 files changed, 14 insertions(+), 15 deletions(-)

diff --git a/arch/x86/kernel/asm-offsets_64.c b/arch/x86/kernel/asm-offsets_64.c
--- a/arch/x86/kernel/asm-offsets_64.c
+++ b/arch/x86/kernel/asm-offsets_64.c
@@ -63,7 +63,7 @@
        OFFSET(PV_IRQ_irq_enable, pv_irq_ops, irq_enable);
        OFFSET(PV_CPU_iret, pv_cpu_ops, iret);
        OFFSET(PV_CPU_nmi_return, pv_cpu_ops, nmi_return);
-       OFFSET(PV_CPU_usersp_sysret, pv_cpu_ops, usersp_sysret);
+       OFFSET(PV_CPU_usergs_sysret, pv_cpu_ops, usergs_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_64.S b/arch/x86/kernel/entry_64.S
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -167,8 +167,7 @@
 #endif 
 
 #ifdef CONFIG_PARAVIRT
-ENTRY(native_usersp_sysret)
-       movq    %gs:pda_oldrsp,%rsp
+ENTRY(native_usergs_sysret)
        swapgs
        sysretq
 #endif /* CONFIG_PARAVIRT */
@@ -383,7 +382,8 @@
        CFI_REGISTER    rip,rcx
        RESTORE_ARGS 0,-ARG_SKIP,1
        /*CFI_REGISTER  rflags,r11*/
-       USERSP_SYSRET
+       movq    %gs:pda_oldrsp, %rsp
+       USERGS_SYSRET
 
        CFI_RESTORE_STATE
        /* Handle reschedules */
diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -142,7 +142,7 @@
        else if (type == PARAVIRT_PATCH(pv_cpu_ops.iret) ||
                 type == PARAVIRT_PATCH(pv_cpu_ops.nmi_return) ||
                 type == PARAVIRT_PATCH(pv_cpu_ops.irq_enable_sysexit) ||
-                type == PARAVIRT_PATCH(pv_cpu_ops.usersp_sysret))
+                type == PARAVIRT_PATCH(pv_cpu_ops.usergs_sysret))
                /* If operation requires a jmp, then jmp */
                ret = paravirt_patch_jmp(insnbuf, opfunc, addr, len);
        else
@@ -195,7 +195,7 @@
 extern void native_iret(void);
 extern void native_nmi_return(void);
 extern void native_irq_enable_sysexit(void);
-extern void native_usersp_sysret(void);
+extern void native_usergs_sysret(void);
 
 static int __init print_banner(void)
 {
@@ -334,7 +334,7 @@
 #ifdef CONFIG_X86_32
        .irq_enable_sysexit = native_irq_enable_sysexit,
 #else
-       .usersp_sysret = native_usersp_sysret,
+       .usergs_sysret = native_usergs_sysret,
 #endif
        .iret = native_iret,
        .nmi_return = native_nmi_return,
diff --git a/arch/x86/kernel/paravirt_patch_64.c 
b/arch/x86/kernel/paravirt_patch_64.c
--- a/arch/x86/kernel/paravirt_patch_64.c
+++ b/arch/x86/kernel/paravirt_patch_64.c
@@ -18,7 +18,7 @@
 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, usersp_sysret, "movq %gs:" __stringify(pda_oldrsp) ", 
%rsp; swapgs; sysretq;");
+DEF_NATIVE(pv_cpu_ops, usergs_sysret, "swapgs; sysretq;");
 DEF_NATIVE(pv_cpu_ops, swapgs, "swapgs");
 
 unsigned native_patch(u8 type, u16 clobbers, void *ibuf,
@@ -39,7 +39,7 @@
                PATCH_SITE(pv_irq_ops, irq_disable);
                PATCH_SITE(pv_cpu_ops, iret);
                PATCH_SITE(pv_cpu_ops, nmi_return);
-               PATCH_SITE(pv_cpu_ops, usersp_sysret);
+               PATCH_SITE(pv_cpu_ops, usergs_sysret);
                PATCH_SITE(pv_cpu_ops, swapgs);
                PATCH_SITE(pv_mmu_ops, read_cr2);
                PATCH_SITE(pv_mmu_ops, read_cr3);
diff --git a/include/asm-x86/irqflags.h b/include/asm-x86/irqflags.h
--- a/include/asm-x86/irqflags.h
+++ b/include/asm-x86/irqflags.h
@@ -168,8 +168,7 @@
 
 #ifdef CONFIG_X86_64
 #define INTERRUPT_RETURN       iretq
-#define USERSP_SYSRET                                  \
-                       movq    %gs:pda_oldrsp, %rsp;   \
+#define USERGS_SYSRET                                  \
                        swapgs;                         \
                        sysretq;
 #else
diff --git a/include/asm-x86/paravirt.h b/include/asm-x86/paravirt.h
--- a/include/asm-x86/paravirt.h
+++ b/include/asm-x86/paravirt.h
@@ -143,7 +143,7 @@
 
        /* These ones are jmp'ed to, not actually called. */
        void (*irq_enable_sysexit)(void);
-       void (*usersp_sysret)(void);
+       void (*usergs_sysret)(void);
        void (*iret)(void);
        void (*nmi_return)(void);
 
@@ -1510,10 +1510,10 @@
        movq %rax, %rcx;                                \
        xorq %rax, %rax;
 
-#define USERSP_SYSRET                                                  \
-       PARA_SITE(PARA_PATCH(pv_cpu_ops, PV_CPU_usersp_sysret),         \
+#define USERGS_SYSRET                                                  \
+       PARA_SITE(PARA_PATCH(pv_cpu_ops, PV_CPU_usergs_sysret),         \
                  CLBR_NONE,                                            \
-                 jmp PARA_INDIRECT(pv_cpu_ops+PV_CPU_usersp_sysret))
+                 jmp PARA_INDIRECT(pv_cpu_ops+PV_CPU_usergs_sysret))
 #endif
 
 #endif /* __ASSEMBLY__ */



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