xen/arch/x86/boot/trampoline.S | 67 ++++++++++++++++++------------------------ 1 file changed, 28 insertions(+), 39 deletions(-)
... to separate code from data. In particular, trampoline_realmode_entry's
write to trampoline_cpu_started clobbers the I-cache line containing
trampoline_protmode_entry, which won't be great for AP startup.
Reformat the comments for trampoline_gdt to reduce their volume.
No functional change.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
---
CC: Jan Beulich <JBeulich@suse.com>
CC: Wei Liu <wl@xen.org>
CC: Roger Pau Monné <roger.pau@citrix.com>
---
xen/arch/x86/boot/trampoline.S | 67 ++++++++++++++++++------------------------
1 file changed, 28 insertions(+), 39 deletions(-)
diff --git a/xen/arch/x86/boot/trampoline.S b/xen/arch/x86/boot/trampoline.S
index 1761fc1213..1b11b4757a 100644
--- a/xen/arch/x86/boot/trampoline.S
+++ b/xen/arch/x86/boot/trampoline.S
@@ -59,45 +59,6 @@ GLOBAL(trampoline_realmode_entry)
lmsw %ax # CR0.PE = 1 (enter protected mode)
ljmpl $BOOT_CS32,$bootsym_rel(trampoline_protmode_entry,6)
-trampoline_gdt:
- /* 0x0000: unused */
- .quad 0x0000000000000000
- /* 0x0008: ring 0 code, 32-bit mode */
- .quad 0x00cf9b000000ffff
- /* 0x0010: ring 0 code, 64-bit mode */
- .quad 0x00af9b000000ffff
- /* 0x0018: ring 0 data */
- .quad 0x00cf93000000ffff
- /* 0x0020: real-mode code @ BOOT_TRAMPOLINE */
- .long 0x0000ffff
- .long 0x00009b00
- /* 0x0028: real-mode data @ BOOT_TRAMPOLINE */
- .long 0x0000ffff
- .long 0x00009300
- /*
- * 0x0030: ring 0 Xen data, 16 MiB size, base
- * address is computed at runtime.
- */
- .quad 0x00c0930000000fff
-.Ltramopline_gdt_end:
-
- .pushsection .trampoline_rel, "a"
- .long trampoline_gdt + BOOT_PSEUDORM_CS + 2 - .
- .long trampoline_gdt + BOOT_PSEUDORM_DS + 2 - .
- .popsection
-
-GLOBAL(trampoline_misc_enable_off)
- .quad 0
-
-GLOBAL(cpuid_ext_features)
- .long 0
-
-GLOBAL(trampoline_xen_phys_start)
- .long 0
-
-GLOBAL(trampoline_cpu_started)
- .byte 0
-
.code32
trampoline_protmode_entry:
/* Set up a few descriptors: on entry only CS is guaranteed good. */
@@ -186,6 +147,34 @@ idt_48: .word 0, 0, 0 # base = limit = 0
gdt_48: .word .Ltramopline_gdt_end - trampoline_gdt - 1
.long bootsym_rel(trampoline_gdt,4)
+trampoline_gdt:
+ .quad 0x0000000000000000 /* 0x0000: unused */
+ .quad 0x00cf9b000000ffff /* 0x0008: ring 0 code, 32-bit mode */
+ .quad 0x00af9b000000ffff /* 0x0010: ring 0 code, 64-bit mode */
+ .quad 0x00cf93000000ffff /* 0x0018: ring 0 data */
+ .quad 0x00009b000000ffff /* 0x0020: real-mode code @ BOOT_TRAMPOLINE */
+ .quad 0x000093000000ffff /* 0x0028: real-mode data @ BOOT_TRAMPOLINE */
+ .quad 0x00c0930000000fff /* 0x0030: ring 0 Xen data, 16M @ XEN */
+.Ltramopline_gdt_end:
+
+ /* Relocations for trampoline Real Mode segments. */
+ .pushsection .trampoline_rel, "a"
+ .long trampoline_gdt + BOOT_PSEUDORM_CS + 2 - .
+ .long trampoline_gdt + BOOT_PSEUDORM_DS + 2 - .
+ .popsection
+
+GLOBAL(trampoline_misc_enable_off)
+ .quad 0
+
+GLOBAL(cpuid_ext_features)
+ .long 0
+
+GLOBAL(trampoline_xen_phys_start)
+ .long 0
+
+GLOBAL(trampoline_cpu_started)
+ .byte 0
+
/* The first page of trampoline is permanent, the rest boot-time only. */
/* Reuse the boot trampoline on the 1st trampoline page as stack for wakeup. */
.equ wakeup_stack, trampoline_start + PAGE_SIZE
--
2.11.0
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On 19.08.2019 15:42, Andrew Cooper wrote: > ... to separate code from data. In particular, trampoline_realmode_entry's > write to trampoline_cpu_started clobbers the I-cache line containing > trampoline_protmode_entry, which won't be great for AP startup. > > Reformat the comments for trampoline_gdt to reduce their volume. > > No functional change. > > Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> Acked-by: Jan Beulich <jbeulich@suse.com> , ... subject to David's concern wrt his series. Jan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
On Mon, 2019-08-19 at 14:42 +0100, Andrew Cooper wrote: > ... to separate code from data. In particular, > trampoline_realmode_entry's > write to trampoline_cpu_started clobbers the I-cache line containing > trampoline_protmode_entry, which won't be great for AP startup. > > Reformat the comments for trampoline_gdt to reduce their volume. > > No functional change. Please, let's not do this one until my other boot cleanups have landed. It just hurts. I have also reordered some of these for functional reasons, because they are used in different contexts (and end up in completely different trampolines). > Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> > --- > CC: Jan Beulich <JBeulich@suse.com> > CC: Wei Liu <wl@xen.org> > CC: Roger Pau Monné <roger.pau@citrix.com> > --- > xen/arch/x86/boot/trampoline.S | 67 ++++++++++++++++++------------ > ------------ > 1 file changed, 28 insertions(+), 39 deletions(-) > > diff --git a/xen/arch/x86/boot/trampoline.S > b/xen/arch/x86/boot/trampoline.S > index 1761fc1213..1b11b4757a 100644 > --- a/xen/arch/x86/boot/trampoline.S > +++ b/xen/arch/x86/boot/trampoline.S > @@ -59,45 +59,6 @@ GLOBAL(trampoline_realmode_entry) > lmsw %ax # CR0.PE = 1 (enter > protected mode) > ljmpl $BOOT_CS32,$bootsym_rel(trampoline_protmode_entry,6) > > -trampoline_gdt: > - /* 0x0000: unused */ > - .quad 0x0000000000000000 > - /* 0x0008: ring 0 code, 32-bit mode */ > - .quad 0x00cf9b000000ffff > - /* 0x0010: ring 0 code, 64-bit mode */ > - .quad 0x00af9b000000ffff > - /* 0x0018: ring 0 data */ > - .quad 0x00cf93000000ffff > - /* 0x0020: real-mode code @ BOOT_TRAMPOLINE */ > - .long 0x0000ffff > - .long 0x00009b00 > - /* 0x0028: real-mode data @ BOOT_TRAMPOLINE */ > - .long 0x0000ffff > - .long 0x00009300 > - /* > - * 0x0030: ring 0 Xen data, 16 MiB size, base > - * address is computed at runtime. > - */ > - .quad 0x00c0930000000fff > -.Ltramopline_gdt_end: > - > - .pushsection .trampoline_rel, "a" > - .long trampoline_gdt + BOOT_PSEUDORM_CS + 2 - . > - .long trampoline_gdt + BOOT_PSEUDORM_DS + 2 - . > - .popsection > - > -GLOBAL(trampoline_misc_enable_off) > - .quad 0 > - > -GLOBAL(cpuid_ext_features) > - .long 0 > - > -GLOBAL(trampoline_xen_phys_start) > - .long 0 > - > -GLOBAL(trampoline_cpu_started) > - .byte 0 > - > .code32 > trampoline_protmode_entry: > /* Set up a few descriptors: on entry only CS is guaranteed > good. */ > @@ -186,6 +147,34 @@ idt_48: .word 0, 0, 0 # base = limit = 0 > gdt_48: .word .Ltramopline_gdt_end - trampoline_gdt - 1 > .long bootsym_rel(trampoline_gdt,4) > > +trampoline_gdt: > + .quad 0x0000000000000000 /* 0x0000: unused */ > + .quad 0x00cf9b000000ffff /* 0x0008: ring 0 code, 32-bit > mode */ > + .quad 0x00af9b000000ffff /* 0x0010: ring 0 code, 64-bit > mode */ > + .quad 0x00cf93000000ffff /* 0x0018: ring 0 data */ > + .quad 0x00009b000000ffff /* 0x0020: real-mode code @ > BOOT_TRAMPOLINE */ > + .quad 0x000093000000ffff /* 0x0028: real-mode data @ > BOOT_TRAMPOLINE */ > + .quad 0x00c0930000000fff /* 0x0030: ring 0 Xen data, 16M @ > XEN */ > +.Ltramopline_gdt_end: > + > + /* Relocations for trampoline Real Mode segments. */ > + .pushsection .trampoline_rel, "a" > + .long trampoline_gdt + BOOT_PSEUDORM_CS + 2 - . > + .long trampoline_gdt + BOOT_PSEUDORM_DS + 2 - . > + .popsection > + > +GLOBAL(trampoline_misc_enable_off) > + .quad 0 > + > +GLOBAL(cpuid_ext_features) > + .long 0 > + > +GLOBAL(trampoline_xen_phys_start) > + .long 0 > + > +GLOBAL(trampoline_cpu_started) > + .byte 0 > + > /* The first page of trampoline is permanent, the rest boot-time > only. */ > /* Reuse the boot trampoline on the 1st trampoline page as stack for > wakeup. */ > .equ wakeup_stack, trampoline_start + PAGE_SIZE _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
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