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Subject[PATCH v2 3/9] x86/paravirt: Replace paravirt patches with data
Date
From: Andi Kleen <ak@linux.intel.com>

For LTO all top level assembler statements need to be global because
LTO might put it into a different assembler file than the referencing
C code.

To avoid making all the paravirt patch snippets global replace them
with data containing the patch instructions. Since these are unlikely
to change this shouldn't be a significant maintenance burden.

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
---
arch/x86/include/asm/paravirt_types.h | 6 +---
arch/x86/kernel/paravirt_patch_32.c | 33 +++++++++++----------
arch/x86/kernel/paravirt_patch_64.c | 42 +++++++++++++++------------
3 files changed, 42 insertions(+), 39 deletions(-)

diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h
index 2474e434a6f7..bb13e79d4344 100644
--- a/arch/x86/include/asm/paravirt_types.h
+++ b/arch/x86/include/asm/paravirt_types.h
@@ -367,12 +367,8 @@ extern struct paravirt_patch_template pv_ops;
#define paravirt_alt(insn_string) \
_paravirt_alt(insn_string, "%c[paravirt_typenum]", "%c[paravirt_clobber]")

-/* Simple instruction patching code. */
-#define NATIVE_LABEL(a,x,b) "\n\t.globl " a #x "_" #b "\n" a #x "_" #b ":\n\t"
-
#define DEF_NATIVE(ops, name, code) \
- __visible extern const char start_##ops##_##name[], end_##ops##_##name[]; \
- asm(NATIVE_LABEL("start_", ops, name) code NATIVE_LABEL("end_", ops, name))
+ const char start_##ops##_##name[] = code

unsigned paravirt_patch_ident_64(void *insnbuf, unsigned len);
unsigned paravirt_patch_default(u8 type, void *insnbuf,
diff --git a/arch/x86/kernel/paravirt_patch_32.c b/arch/x86/kernel/paravirt_patch_32.c
index de138d3912e4..9a649026d74c 100644
--- a/arch/x86/kernel/paravirt_patch_32.c
+++ b/arch/x86/kernel/paravirt_patch_32.c
@@ -2,14 +2,14 @@
#include <asm/paravirt.h>

#ifdef CONFIG_PARAVIRT_XXL
-DEF_NATIVE(irq, irq_disable, "cli");
-DEF_NATIVE(irq, irq_enable, "sti");
-DEF_NATIVE(irq, restore_fl, "push %eax; popf");
-DEF_NATIVE(irq, save_fl, "pushf; pop %eax");
-DEF_NATIVE(cpu, iret, "iret");
-DEF_NATIVE(mmu, read_cr2, "mov %cr2, %eax");
-DEF_NATIVE(mmu, write_cr3, "mov %eax, %cr3");
-DEF_NATIVE(mmu, read_cr3, "mov %cr3, %eax");
+static const unsigned char patch_irq_irq_disable[] = { 0xfa }; /* cli */
+static const unsigned char patch_irq_irq_enable[] = { 0xfb }; /* sti */
+static const unsigned char patch_irq_restore_fl[] = { 0x50, 0x9d }; /* push %eax; popf */
+static const unsigned char patch_irq_save_fl[] = { 0x9c, 0x58 }; /* pushf; pop %eax */
+static const unsigned char patch_cpu_iret[] = { 0xcf }; /* iret */
+static const unsigned char patch_mmu_read_cr2[] = { 0x0f, 0x20, 0xd0 }; /* mov %cr2, %eax */
+static const unsigned char patch_mmu_write_cr3[] = { 0x0f, 0x22, 0xd8 };/* mov %eax, %cr3 */
+static const unsigned char patch_mmu_read_cr3[] = { 0x0f, 0x20, 0xd8 }; /* mov %cr3, %eax */

unsigned paravirt_patch_ident_64(void *insnbuf, unsigned len)
{
@@ -19,8 +19,8 @@ unsigned paravirt_patch_ident_64(void *insnbuf, unsigned len)
#endif

#if defined(CONFIG_PARAVIRT_SPINLOCKS)
-DEF_NATIVE(lock, queued_spin_unlock, "movb $0, (%eax)");
-DEF_NATIVE(lock, vcpu_is_preempted, "xor %eax, %eax");
+static const unsigned char patch_lock_queued_spin_unlock[] = { 0xc6, 0x00, 0x00 }; /* movb $0, (%eax) */
+static const unsigned char patch_lock_vcpu_is_preempted[] = { 0x31, 0xc0 }; /* xor %eax, %eax */
#endif

extern bool pv_is_native_spin_unlock(void);
@@ -30,7 +30,8 @@ unsigned native_patch(u8 type, void *ibuf, unsigned long addr, unsigned len)
{
#define PATCH_SITE(ops, x) \
case PARAVIRT_PATCH(ops.x): \
- return paravirt_patch_insns(ibuf, len, start_##ops##_##x, end_##ops##_##x)
+ return paravirt_patch_insns(ibuf, len, \
+ patch_##ops##_##x, patch_##ops##_##x+sizeof(patch_##ops##_x));

switch (type) {
#ifdef CONFIG_PARAVIRT_XXL
@@ -47,15 +48,17 @@ unsigned native_patch(u8 type, void *ibuf, unsigned long addr, unsigned len)
case PARAVIRT_PATCH(lock.queued_spin_unlock):
if (pv_is_native_spin_unlock())
return paravirt_patch_insns(ibuf, len,
- start_lock_queued_spin_unlock,
- end_lock_queued_spin_unlock);
+ patch_lock_queued_spin_unlock,
+ patch_lock_queued_spin_unlock +
+ sizeof(patch_lock_queued_spin_unlock));
break;

case PARAVIRT_PATCH(lock.vcpu_is_preempted):
if (pv_is_native_vcpu_is_preempted())
return paravirt_patch_insns(ibuf, len,
- start_lock_vcpu_is_preempted,
- end_lock_vcpu_is_preempted);
+ patch_lock_vcpu_is_preempted,
+ patch_lock_vcpu_is_preempted +
+ sizeof(patch_lock_vcpu_is_preempted));
break;
#endif

diff --git a/arch/x86/kernel/paravirt_patch_64.c b/arch/x86/kernel/paravirt_patch_64.c
index 9d9e04b31077..fce6f54665d3 100644
--- a/arch/x86/kernel/paravirt_patch_64.c
+++ b/arch/x86/kernel/paravirt_patch_64.c
@@ -4,29 +4,30 @@
#include <linux/stringify.h>

#ifdef CONFIG_PARAVIRT_XXL
-DEF_NATIVE(irq, irq_disable, "cli");
-DEF_NATIVE(irq, irq_enable, "sti");
-DEF_NATIVE(irq, restore_fl, "pushq %rdi; popfq");
-DEF_NATIVE(irq, save_fl, "pushfq; popq %rax");
-DEF_NATIVE(mmu, read_cr2, "movq %cr2, %rax");
-DEF_NATIVE(mmu, read_cr3, "movq %cr3, %rax");
-DEF_NATIVE(mmu, write_cr3, "movq %rdi, %cr3");
-DEF_NATIVE(cpu, wbinvd, "wbinvd");
+static const unsigned char patch_irq_irq_disable[] = { 0xfa }; /* cli */
+static const unsigned char patch_irq_irq_enable[] = { 0xfb }; /* sti */
+static const unsigned char patch_irq_restore_fl[] = { 0x50, 0x9d}; /* pushq %rdi; popfq */
+static const unsigned char patch_irq_save_fl[] = { 0x9c, 0x58 }; /* pushfq; popq %rax */
+static const unsigned char patch_mmu_read_cr2[] = { 0x0f, 0x20, 0xd0 }; /* movq %cr2, %rax */
+static const unsigned char patch_mmu_read_cr3[] = { 0x0f, 0x22, 0xd8 }; /* movq %cr3, %rax */
+static const unsigned char patch_mmu_write_cr3[] = { 0x0f, 0x22, 0xdf }; /* movq %rdi, %cr3 */
+static const unsigned char patch_cpu_wbinvd[] = { 0x0f, 0x09 }; /* wbinvd */

-DEF_NATIVE(cpu, usergs_sysret64, "swapgs; sysretq");
-DEF_NATIVE(cpu, swapgs, "swapgs");
-DEF_NATIVE(, mov64, "mov %rdi, %rax");
+static const unsigned char patch_cpu_usergs_sysret64[] = { 0x0f, 0x01, 0xf8, 0x48, 0x0f, 0x07 };
+ /* swapgs; sysretq */
+static const unsigned char patch_cpu_swapgs[] = { 0x0f, 0x01, 0xf8 }; /* swapgs */
+static const unsigned char patch_mov64[] = { 0x48, 0x89, 0xf8 }; /* mov %rdi, %rax */

unsigned paravirt_patch_ident_64(void *insnbuf, unsigned len)
{
return paravirt_patch_insns(insnbuf, len,
- start__mov64, end__mov64);
+ start_mov64, start_mov64 + sizeof(start_mov64));
}
#endif

#if defined(CONFIG_PARAVIRT_SPINLOCKS)
-DEF_NATIVE(lock, queued_spin_unlock, "movb $0, (%rdi)");
-DEF_NATIVE(lock, vcpu_is_preempted, "xor %eax, %eax");
+static const unsigned char patch_lock_queued_spin_unlock[] = { 0xc6, 0x07, 0x00}; /* movb $0, (%rdi) */
+static const unsigned char patch_lock_vcpu_is_preempted[] = { 0x31, 0xc0 }; /* xor %eax, %eax */
#endif

extern bool pv_is_native_spin_unlock(void);
@@ -36,7 +37,8 @@ unsigned native_patch(u8 type, void *ibuf, unsigned long addr, unsigned len)
{
#define PATCH_SITE(ops, x) \
case PARAVIRT_PATCH(ops.x): \
- return paravirt_patch_insns(ibuf, len, start_##ops##_##x, end_##ops##_##x)
+ return paravirt_patch_insns(ibuf, len, start_##ops##_##x, \
+ patch_##ops##_##x + sizeof(patch_##ops##_##x));

switch (type) {
#ifdef CONFIG_PARAVIRT_XXL
@@ -55,15 +57,17 @@ unsigned native_patch(u8 type, void *ibuf, unsigned long addr, unsigned len)
case PARAVIRT_PATCH(lock.queued_spin_unlock):
if (pv_is_native_spin_unlock())
return paravirt_patch_insns(ibuf, len,
- start_lock_queued_spin_unlock,
- end_lock_queued_spin_unlock);
+ patch_lock_queued_spin_unlock,
+ patch_lock_queued_spin_unlock +
+ sizeof(patch_lock_queued_spin_unlock));
break;

case PARAVIRT_PATCH(lock.vcpu_is_preempted):
if (pv_is_native_vcpu_is_preempted())
return paravirt_patch_insns(ibuf, len,
- start_lock_vcpu_is_preempted,
- end_lock_vcpu_is_preempted);
+ patch_lock_vcpu_is_preempted,
+ patch_lock_vcpu_is_preempted +
+ sizeof(patch_lock_vcpu_is_preempted));
break;
#endif

--
2.20.1
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