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Subject[tip:x86/asm] x86/paravirt/xen: Remove xen_patch()
Commit-ID:  edcb5cf84f05e5d2e2af25422a72ccde359fcca9
Gitweb: http://git.kernel.org/tip/edcb5cf84f05e5d2e2af25422a72ccde359fcca9
Author: Juergen Gross <jgross@suse.com>
AuthorDate: Wed, 16 Aug 2017 19:31:56 +0200
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Thu, 24 Aug 2017 09:57:24 +0200

x86/paravirt/xen: Remove xen_patch()

Xen's paravirt patch function xen_patch() does some special casing for
irq_ops functions to apply relocations when those functions can be
patched inline instead of calls.

Unfortunately none of the special case function replacements is small
enough to be patched inline, so the special case never applies.

As xen_patch() will call paravirt_patch_default() in all cases it can
be just dropped. xen-asm.h doesn't seem necessary without xen_patch()
as the only thing left in it would be the definition of XEN_EFLAGS_NMI
used only once. So move that definition and remove xen-asm.h.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: boris.ostrovsky@oracle.com
Cc: lguest@lists.ozlabs.org
Cc: rusty@rustcorp.com.au
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/20170816173157.8633-2-jgross@suse.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/xen/enlighten_pv.c | 59 +--------------------------------------------
arch/x86/xen/xen-asm.S | 26 +++++---------------
arch/x86/xen/xen-asm.h | 12 ---------
arch/x86/xen/xen-asm_32.S | 27 ++++-----------------
arch/x86/xen/xen-asm_64.S | 20 ++++-----------
arch/x86/xen/xen-ops.h | 15 +++---------
6 files changed, 21 insertions(+), 138 deletions(-)

diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
index 811e4dd..9849152 100644
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -981,59 +981,6 @@ void __ref xen_setup_vcpu_info_placement(void)
}
}

-static unsigned xen_patch(u8 type, u16 clobbers, void *insnbuf,
- unsigned long addr, unsigned len)
-{
- char *start, *end, *reloc;
- unsigned ret;
-
- start = end = reloc = NULL;
-
-#define SITE(op, x) \
- case PARAVIRT_PATCH(op.x): \
- if (xen_have_vcpu_info_placement) { \
- start = (char *)xen_##x##_direct; \
- end = xen_##x##_direct_end; \
- reloc = xen_##x##_direct_reloc; \
- } \
- goto patch_site
-
- switch (type) {
- SITE(pv_irq_ops, irq_enable);
- SITE(pv_irq_ops, irq_disable);
- SITE(pv_irq_ops, save_fl);
- SITE(pv_irq_ops, restore_fl);
-#undef SITE
-
- patch_site:
- if (start == NULL || (end-start) > len)
- goto default_patch;
-
- ret = paravirt_patch_insns(insnbuf, len, start, end);
-
- /* Note: because reloc is assigned from something that
- appears to be an array, gcc assumes it's non-null,
- but doesn't know its relationship with start and
- end. */
- if (reloc > start && reloc < end) {
- int reloc_off = reloc - start;
- long *relocp = (long *)(insnbuf + reloc_off);
- long delta = start - (char *)addr;
-
- *relocp += delta;
- }
- break;
-
- default_patch:
- default:
- ret = paravirt_patch_default(type, clobbers, insnbuf,
- addr, len);
- break;
- }
-
- return ret;
-}
-
static const struct pv_info xen_info __initconst = {
.shared_kernel_pmd = 0,

@@ -1043,10 +990,6 @@ static const struct pv_info xen_info __initconst = {
.name = "Xen",
};

-static const struct pv_init_ops xen_init_ops __initconst = {
- .patch = xen_patch,
-};
-
static const struct pv_cpu_ops xen_cpu_ops __initconst = {
.cpuid = xen_cpuid,

@@ -1244,7 +1187,7 @@ asmlinkage __visible void __init xen_start_kernel(void)

/* Install Xen paravirt ops */
pv_info = xen_info;
- pv_init_ops = xen_init_ops;
+ pv_init_ops.patch = paravirt_patch_default;
pv_cpu_ops = xen_cpu_ops;

x86_platform.get_nmi_reason = xen_get_nmi_reason;
diff --git a/arch/x86/xen/xen-asm.S b/arch/x86/xen/xen-asm.S
index eff224d..dcd31fa 100644
--- a/arch/x86/xen/xen-asm.S
+++ b/arch/x86/xen/xen-asm.S
@@ -1,14 +1,8 @@
/*
- * Asm versions of Xen pv-ops, suitable for either direct use or
- * inlining. The inline versions are the same as the direct-use
- * versions, with the pre- and post-amble chopped off.
- *
- * This code is encoded for size rather than absolute efficiency, with
- * a view to being able to inline as much as possible.
+ * Asm versions of Xen pv-ops, suitable for direct use.
*
* We only bother with direct forms (ie, vcpu in percpu data) of the
- * operations here; the indirect forms are better handled in C, since
- * they're generally too large to inline anyway.
+ * operations here; the indirect forms are better handled in C.
*/

#include <asm/asm-offsets.h>
@@ -16,7 +10,7 @@
#include <asm/processor-flags.h>
#include <asm/frame.h>

-#include "xen-asm.h"
+#include <linux/linkage.h>

/*
* Enable events. This clears the event mask and tests the pending
@@ -38,13 +32,11 @@ ENTRY(xen_irq_enable_direct)
testb $0xff, PER_CPU_VAR(xen_vcpu_info) + XEN_vcpu_info_pending
jz 1f

-2: call check_events
+ call check_events
1:
-ENDPATCH(xen_irq_enable_direct)
FRAME_END
ret
ENDPROC(xen_irq_enable_direct)
- RELOC(xen_irq_enable_direct, 2b+1)


/*
@@ -53,10 +45,8 @@ ENDPATCH(xen_irq_enable_direct)
*/
ENTRY(xen_irq_disable_direct)
movb $1, PER_CPU_VAR(xen_vcpu_info) + XEN_vcpu_info_mask
-ENDPATCH(xen_irq_disable_direct)
ret
- ENDPROC(xen_irq_disable_direct)
- RELOC(xen_irq_disable_direct, 0)
+ENDPROC(xen_irq_disable_direct)

/*
* (xen_)save_fl is used to get the current interrupt enable status.
@@ -71,10 +61,8 @@ ENTRY(xen_save_fl_direct)
testb $0xff, PER_CPU_VAR(xen_vcpu_info) + XEN_vcpu_info_mask
setz %ah
addb %ah, %ah
-ENDPATCH(xen_save_fl_direct)
ret
ENDPROC(xen_save_fl_direct)
- RELOC(xen_save_fl_direct, 0)


/*
@@ -101,13 +89,11 @@ ENTRY(xen_restore_fl_direct)
/* check for unmasked and pending */
cmpw $0x0001, PER_CPU_VAR(xen_vcpu_info) + XEN_vcpu_info_pending
jnz 1f
-2: call check_events
+ call check_events
1:
-ENDPATCH(xen_restore_fl_direct)
FRAME_END
ret
ENDPROC(xen_restore_fl_direct)
- RELOC(xen_restore_fl_direct, 2b+1)


/*
diff --git a/arch/x86/xen/xen-asm.h b/arch/x86/xen/xen-asm.h
deleted file mode 100644
index 4652764..0000000
--- a/arch/x86/xen/xen-asm.h
+++ /dev/null
@@ -1,12 +0,0 @@
-#ifndef _XEN_XEN_ASM_H
-#define _XEN_XEN_ASM_H
-
-#include <linux/linkage.h>
-
-#define RELOC(x, v) .globl x##_reloc; x##_reloc=v
-#define ENDPATCH(x) .globl x##_end; x##_end=.
-
-/* Pseudo-flag used for virtual NMI, which we don't implement yet */
-#define XEN_EFLAGS_NMI 0x80000000
-
-#endif
diff --git a/arch/x86/xen/xen-asm_32.S b/arch/x86/xen/xen-asm_32.S
index feb6d40..1200e26 100644
--- a/arch/x86/xen/xen-asm_32.S
+++ b/arch/x86/xen/xen-asm_32.S
@@ -1,14 +1,8 @@
/*
- * Asm versions of Xen pv-ops, suitable for either direct use or
- * inlining. The inline versions are the same as the direct-use
- * versions, with the pre- and post-amble chopped off.
- *
- * This code is encoded for size rather than absolute efficiency, with
- * a view to being able to inline as much as possible.
+ * Asm versions of Xen pv-ops, suitable for direct use.
*
* We only bother with direct forms (ie, vcpu in pda) of the
- * operations here; the indirect forms are better handled in C, since
- * they're generally too large to inline anyway.
+ * operations here; the indirect forms are better handled in C.
*/

#include <asm/thread_info.h>
@@ -18,21 +12,10 @@

#include <xen/interface/xen.h>

-#include "xen-asm.h"
+#include <linux/linkage.h>

-/*
- * Force an event check by making a hypercall, but preserve regs
- * before making the call.
- */
-check_events:
- push %eax
- push %ecx
- push %edx
- call xen_force_evtchn_callback
- pop %edx
- pop %ecx
- pop %eax
- ret
+/* Pseudo-flag used for virtual NMI, which we don't implement yet */
+#define XEN_EFLAGS_NMI 0x80000000

/*
* This is run where a normal iret would be run, with the same stack setup:
diff --git a/arch/x86/xen/xen-asm_64.S b/arch/x86/xen/xen-asm_64.S
index c5fee26..3a3b6a2 100644
--- a/arch/x86/xen/xen-asm_64.S
+++ b/arch/x86/xen/xen-asm_64.S
@@ -1,14 +1,8 @@
/*
- * Asm versions of Xen pv-ops, suitable for either direct use or
- * inlining. The inline versions are the same as the direct-use
- * versions, with the pre- and post-amble chopped off.
- *
- * This code is encoded for size rather than absolute efficiency, with
- * a view to being able to inline as much as possible.
+ * Asm versions of Xen pv-ops, suitable for direct use.
*
* We only bother with direct forms (ie, vcpu in pda) of the
- * operations here; the indirect forms are better handled in C, since
- * they're generally too large to inline anyway.
+ * operations here; the indirect forms are better handled in C.
*/

#include <asm/errno.h>
@@ -20,7 +14,7 @@

#include <xen/interface/xen.h>

-#include "xen-asm.h"
+#include <linux/linkage.h>

ENTRY(xen_adjust_exception_frame)
mov 8+0(%rsp), %rcx
@@ -46,9 +40,7 @@ hypercall_iret = hypercall_page + __HYPERVISOR_iret * 32
*/
ENTRY(xen_iret)
pushq $0
-1: jmp hypercall_iret
-ENDPATCH(xen_iret)
-RELOC(xen_iret, 1b+1)
+ jmp hypercall_iret

ENTRY(xen_sysret64)
/*
@@ -65,9 +57,7 @@ ENTRY(xen_sysret64)
pushq %rcx

pushq $VGCF_in_syscall
-1: jmp hypercall_iret
-ENDPATCH(xen_sysret64)
-RELOC(xen_sysret64, 1b+1)
+ jmp hypercall_iret

/*
* Xen handles syscall callbacks much like ordinary exceptions, which
diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h
index 0d50044..70301ac 100644
--- a/arch/x86/xen/xen-ops.h
+++ b/arch/x86/xen/xen-ops.h
@@ -129,17 +129,10 @@ static inline void __init xen_efi_init(void)
}
#endif

-/* Declare an asm function, along with symbols needed to make it
- inlineable */
-#define DECL_ASM(ret, name, ...) \
- __visible ret name(__VA_ARGS__); \
- extern char name##_end[] __visible; \
- extern char name##_reloc[] __visible
-
-DECL_ASM(void, xen_irq_enable_direct, void);
-DECL_ASM(void, xen_irq_disable_direct, void);
-DECL_ASM(unsigned long, xen_save_fl_direct, void);
-DECL_ASM(void, xen_restore_fl_direct, unsigned long);
+__visible void xen_irq_enable_direct(void);
+__visible void xen_irq_disable_direct(void);
+__visible unsigned long xen_save_fl_direct(void);
+__visible void xen_restore_fl_direct(unsigned long);

/* These are not functions, and cannot be called normally */
__visible void xen_iret(void);
\
 
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