[PATCH v2 17/24] x86/xen: Make set_debugreg() noinstr

Peter Zijlstra
2021-06-24T09:56:37Z

vmlinux.o: warning: objtool: pv_ops[2]: xen_set_debugreg
vmlinux.o: warning: objtool: pv_ops[2]: native_set_debugreg
vmlinux.o: warning: objtool: exc_debug()+0x3b: call to pv_ops[2]() leaves .noinstr.text section

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
arch/x86/include/asm/paravirt.h | 2 +-
arch/x86/include/asm/xen/hypercall.h | 2 +-
arch/x86/kernel/paravirt.c | 9 ++++++---
arch/x86/xen/enlighten_pv.c | 2 +-
4 files changed, 9 insertions(+), 6 deletions(-)

--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -118,7 +118,7 @@ static __always_inline unsigned long par
return PVOP_CALL1(unsigned long, cpu.get_debugreg, reg);
}
#define get_debugreg(var, reg) var = paravirt_get_debugreg(reg)
-static inline void set_debugreg(unsigned long val, int reg)
+static __always_inline void set_debugreg(unsigned long val, int reg)
{
PVOP_VCALL2(cpu.set_debugreg, reg, val);
}
--- a/arch/x86/include/asm/xen/hypercall.h
+++ b/arch/x86/include/asm/xen/hypercall.h
@@ -308,7 +308,7 @@ HYPERVISOR_platform_op(struct xen_platfo
return _hypercall1(int, platform_op, op);
}

-static inline int
+static __always_inline int
HYPERVISOR_set_debugreg(int reg, unsigned long value)
{
return _hypercall2(int, set_debugreg, reg, value);
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -253,6 +253,11 @@ static noinstr unsigned long pv_native_g
return native_get_debugreg(regno);
}

+static noinstr void pv_native_set_debugreg(int regno, unsigned long val)
+{
+ native_set_debugreg(regno, val);
+}
+
struct paravirt_patch_template pv_ops = {
/* Cpu ops. */
.cpu.io_delay = native_io_delay,
@@ -260,7 +265,7 @@ struct paravirt_patch_template pv_ops =
#ifdef CONFIG_PARAVIRT_XXL
.cpu.cpuid = native_cpuid,
.cpu.get_debugreg = pv_native_get_debugreg,
- .cpu.set_debugreg = native_set_debugreg,
+ .cpu.set_debugreg = pv_native_set_debugreg,
.cpu.read_cr0 = native_read_cr0,
.cpu.write_cr0 = native_write_cr0,
.cpu.write_cr4 = native_write_cr4,
@@ -386,8 +391,6 @@ struct paravirt_patch_template pv_ops =
};

#ifdef CONFIG_PARAVIRT_XXL
-/* At this point, native_get/set_debugreg has real function entries */
-NOKPROBE_SYMBOL(native_set_debugreg);
NOKPROBE_SYMBOL(native_load_idt);

void (*paravirt_iret)(void) = native_iret;
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -312,7 +312,7 @@ static void __init xen_init_capabilities
}
}

-static void xen_set_debugreg(int reg, unsigned long val)
+static noinstr void xen_set_debugreg(int reg, unsigned long val)
{
HYPERVISOR_set_debugreg(reg, val);
}