Re: [PATCH] [v3] x86: xen: add missing prototypes

From: Juergen Gross
Date: Wed May 24 2023 - 09:25:45 EST

On 23.05.23 22:56, Arnd Bergmann wrote:
From: Arnd Bergmann <arnd@xxxxxxxx>

These function are all called from assembler files, or from inline assembler,
so there is no immediate need for a prototype in a header, but if -Wmissing-prototypes
is enabled, the compiler warns about them:

arch/x86/xen/efi.c:130:13: error: no previous prototype for 'xen_efi_init' [-Werror=missing-prototypes]
arch/x86/platform/pvh/enlighten.c:120:13: error: no previous prototype for 'xen_prepare_pvh' [-Werror=missing-prototypes]
arch/x86/xen/mmu_pv.c:358:20: error: no previous prototype for 'xen_pte_val' [-Werror=missing-prototypes]
arch/x86/xen/mmu_pv.c:366:20: error: no previous prototype for 'xen_pgd_val' [-Werror=missing-prototypes]
arch/x86/xen/mmu_pv.c:372:17: error: no previous prototype for 'xen_make_pte' [-Werror=missing-prototypes]
arch/x86/xen/mmu_pv.c:380:17: error: no previous prototype for 'xen_make_pgd' [-Werror=missing-prototypes]
arch/x86/xen/mmu_pv.c:387:20: error: no previous prototype for 'xen_pmd_val' [-Werror=missing-prototypes]
arch/x86/xen/mmu_pv.c:425:17: error: no previous prototype for 'xen_make_pmd' [-Werror=missing-prototypes]
arch/x86/xen/mmu_pv.c:432:20: error: no previous prototype for 'xen_pud_val' [-Werror=missing-prototypes]
arch/x86/xen/mmu_pv.c:438:17: error: no previous prototype for 'xen_make_pud' [-Werror=missing-prototypes]
arch/x86/xen/mmu_pv.c:522:20: error: no previous prototype for 'xen_p4d_val' [-Werror=missing-prototypes]
arch/x86/xen/mmu_pv.c:528:17: error: no previous prototype for 'xen_make_p4d' [-Werror=missing-prototypes]
arch/x86/xen/mmu_pv.c:1442:17: error: no previous prototype for 'xen_make_pte_init' [-Werror=missing-prototypes]

I'd suggest to add the prototypes of the functions defined in
arch/x86/xen/mmu_pv.c to the same source, as they are referenced
nowhere else. This avoids the need of #ifdefs for those functions.

arch/x86/xen/enlighten_pv.c:1233:34: error: no previous prototype for 'xen_start_kernel' [-Werror=missing-prototypes]
arch/x86/xen/irq.c:22:14: error: no previous prototype for 'xen_force_evtchn_callback' [-Werror=missing-prototypes]
arch/x86/entry/common.c:302:24: error: no previous prototype for 'xen_pv_evtchn_do_upcall' [-Werror=missing-prototypes]

Declare all of them in an appropriate header file to avoid the warnings.
For consistency, also move the asm_cpu_bringup_and_idle() declaration out of

Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
v3: move declations of conditional function in an #ifdef with a stub
v2: fix up changelog
arch/x86/xen/efi.c | 2 ++
arch/x86/xen/smp.h | 11 +++++++++++
arch/x86/xen/smp_pv.c | 1 -
arch/x86/xen/xen-ops.h | 26 ++++++++++++++++++++++++++
include/xen/xen.h | 3 +++
5 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/arch/x86/xen/efi.c b/arch/x86/xen/efi.c
index 7d7ffb9c826a..863d0d6b3edc 100644
--- a/arch/x86/xen/efi.c
+++ b/arch/x86/xen/efi.c
@@ -16,6 +16,8 @@
#include <asm/setup.h>
#include <asm/xen/hypercall.h>
+#include "xen-ops.h"
static efi_char16_t vendor[100] __initdata;
static efi_system_table_t efi_systab_xen __initdata = {
diff --git a/arch/x86/xen/smp.h b/arch/x86/xen/smp.h
index 22fb982ff971..9367502281dc 100644
--- a/arch/x86/xen/smp.h
+++ b/arch/x86/xen/smp.h
@@ -2,6 +2,10 @@
#ifndef _XEN_SMP_H
+void asm_cpu_bringup_and_idle(void);
+asmlinkage void cpu_bringup_and_idle(void);
extern void xen_send_IPI_mask(const struct cpumask *mask,
int vector);
extern void xen_send_IPI_mask_allbutself(const struct cpumask *mask,
@@ -29,6 +33,13 @@ struct xen_common_irq {
#else /* CONFIG_SMP */
+static inline void asm_cpu_bringup_and_idle(void)
+static inline void cpu_bringup_and_idle(void)

No need for above stubs, as there is no way they can get called
without CONFIG_SMP.

static inline int xen_smp_intr_init(unsigned int cpu)
return 0;
diff --git a/arch/x86/xen/smp_pv.c b/arch/x86/xen/smp_pv.c
index a92e8002b5cf..d5ae5de2daa2 100644
--- a/arch/x86/xen/smp_pv.c
+++ b/arch/x86/xen/smp_pv.c
@@ -55,7 +55,6 @@ static DEFINE_PER_CPU(struct xen_common_irq, xen_irq_work) = { .irq = -1 };
static DEFINE_PER_CPU(struct xen_common_irq, xen_pmu_irq) = { .irq = -1 };
static irqreturn_t xen_irq_work_interrupt(int irq, void *dev_id);
-void asm_cpu_bringup_and_idle(void);
static void cpu_bringup(void)
diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h
index 6d7f6318fc07..eb4cb30570c7 100644
--- a/arch/x86/xen/xen-ops.h
+++ b/arch/x86/xen/xen-ops.h
@@ -146,12 +146,38 @@ int xen_cpuhp_setup(int (*cpu_up_prepare_cb)(unsigned int),
void xen_pin_vcpu(int cpu);
void xen_emergency_restart(void);
+void xen_force_evtchn_callback(void);
void xen_pv_pre_suspend(void);
void xen_pv_post_suspend(int suspend_cancelled);
+pteval_t xen_pte_val(pte_t pte);
+pgdval_t xen_pgd_val(pgd_t pgd);
+pmdval_t xen_pmd_val(pmd_t pmd);
+pudval_t xen_pud_val(pud_t pud);
+p4dval_t xen_p4d_val(p4d_t p4d);
+pte_t xen_make_pte(pteval_t pte);
+pgd_t xen_make_pgd(pgdval_t pgd);
+pmd_t xen_make_pmd(pmdval_t pmd);
+pud_t xen_make_pud(pudval_t pud);
+p4d_t xen_make_p4d(p4dval_t p4d);
+pte_t xen_make_pte_init(pteval_t pte);

See above.

+void xen_start_kernel(struct start_info *si);
static inline void xen_pv_pre_suspend(void) {}
static inline void xen_pv_post_suspend(int suspend_cancelled) {}
+static inline pteval_t xen_pte_val(pte_t pte) { return pte.pte; }
+static inline pgdval_t xen_pgd_val(pgd_t pgd) { return pgd.pgd; }
+static inline pmdval_t xen_pmd_val(pmd_t pmd) { return pmd.pmd; }
+static inline pudval_t xen_pud_val(pud_t pud) { return pud.pud; }
+static inline p4dval_t xen_p4d_val(p4d_t p4d) { return p4d.p4d; }
+static inline pte_t xen_make_pte(pteval_t pte) { return (pte_t){pte}; }
+static inline pgd_t xen_make_pgd(pgdval_t pgd) { return (pgd_t){pgd}; }
+static inline pmd_t xen_make_pmd(pmdval_t pmd) { return (pmd_t){pmd}; }
+static inline pud_t xen_make_pud(pudval_t pud) { return (pud_t){pud}; }
+static inline p4d_t xen_make_p4d(p4dval_t p4d) { return (p4d_t){p4d}; }
+static inline pte_t xen_make_pte_init(pteval_t pte) { return (pte_t){pte}; }
+static inline void xen_start_kernel(struct start_info *si) {}

Drop those stubs, they are not used without CONFIG_XEN_PV, and
they shouldn't be used in this case anyway.

diff --git a/include/xen/xen.h b/include/xen/xen.h
index 0efeb652f9b8..f989162983c3 100644
--- a/include/xen/xen.h
+++ b/include/xen/xen.h
@@ -31,6 +31,9 @@ extern uint32_t xen_start_flags;
#include <xen/interface/hvm/start_info.h>
extern struct hvm_start_info pvh_start_info;
+void xen_prepare_pvh(void);
+struct pt_regs;
+void xen_pv_evtchn_do_upcall(struct pt_regs *regs);
#include <xen/interface/xen.h>


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