Re: [PATCH 53/74] x86, lto, paravirt: Make paravirt thunks global

[Jeremy Fitzhardinge <jeremy@goop.org>]

On 08/18/2012 07:56 PM, Andi Kleen wrote:
> From: Andi Kleen <ak@linux.intel.com>
>
> The paravirt thunks use a hack of using a static reference to a static
> function to reference that function from the top level statement.
>
> This assumes that gcc always generates static function names in a specific
> format, which is not necessarily true.
>
> Simply make these functions global and asmlinkage. This way the
> static __used variables are not needed and everything works.

I'm not a huge fan of unstaticing all this stuff, but it doesn't
surprise me that the current code is brittle in the face of gcc changes.

    J

>
> Changed in paravirt and in all users (Xen and vsmp)
>
> Cc: jeremy@goop.org
> Signed-off-by: Andi Kleen <ak@linux.intel.com>
> ---
>  arch/x86/include/asm/paravirt.h |    2 +-
>  arch/x86/kernel/vsmp_64.c       |    8 ++++----
>  arch/x86/xen/irq.c              |    8 ++++----
>  arch/x86/xen/mmu.c              |   16 ++++++++--------
>  4 files changed, 17 insertions(+), 17 deletions(-)
>
> diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
> index a0facf3..cc733a6 100644
> --- a/arch/x86/include/asm/paravirt.h
> +++ b/arch/x86/include/asm/paravirt.h
> @@ -804,9 +804,9 @@ static __always_inline void arch_spin_unlock(struct arch_spinlock *lock)
>   */
>  #define PV_CALLEE_SAVE_REGS_THUNK(func)					\
>  	extern typeof(func) __raw_callee_save_##func;			\
> -	static void *__##func##__ __used = func;			\
>  									\
>  	asm(".pushsection .text;"					\
> +	    ".globl __raw_callee_save_" #func " ; "			\
>  	    "__raw_callee_save_" #func ": "				\
>  	    PV_SAVE_ALL_CALLER_REGS					\
>  	    "call " #func ";"						\
> diff --git a/arch/x86/kernel/vsmp_64.c b/arch/x86/kernel/vsmp_64.c
> index 992f890..f393d6d 100644
> --- a/arch/x86/kernel/vsmp_64.c
> +++ b/arch/x86/kernel/vsmp_64.c
> @@ -33,7 +33,7 @@
>   * and vice versa.
>   */
>  
> -static unsigned long vsmp_save_fl(void)
> +asmlinkage unsigned long vsmp_save_fl(void)
>  {
>  	unsigned long flags = native_save_fl();
>  
> @@ -43,7 +43,7 @@ static unsigned long vsmp_save_fl(void)
>  }
>  PV_CALLEE_SAVE_REGS_THUNK(vsmp_save_fl);
>  
> -static void vsmp_restore_fl(unsigned long flags)
> +asmlinkage void vsmp_restore_fl(unsigned long flags)
>  {
>  	if (flags & X86_EFLAGS_IF)
>  		flags &= ~X86_EFLAGS_AC;
> @@ -53,7 +53,7 @@ static void vsmp_restore_fl(unsigned long flags)
>  }
>  PV_CALLEE_SAVE_REGS_THUNK(vsmp_restore_fl);
>  
> -static void vsmp_irq_disable(void)
> +asmlinkage void vsmp_irq_disable(void)
>  {
>  	unsigned long flags = native_save_fl();
>  
> @@ -61,7 +61,7 @@ static void vsmp_irq_disable(void)
>  }
>  PV_CALLEE_SAVE_REGS_THUNK(vsmp_irq_disable);
>  
> -static void vsmp_irq_enable(void)
> +asmlinkage void vsmp_irq_enable(void)
>  {
>  	unsigned long flags = native_save_fl();
>  
> diff --git a/arch/x86/xen/irq.c b/arch/x86/xen/irq.c
> index 1573376..3dd8831 100644
> --- a/arch/x86/xen/irq.c
> +++ b/arch/x86/xen/irq.c
> @@ -21,7 +21,7 @@ void xen_force_evtchn_callback(void)
>  	(void)HYPERVISOR_xen_version(0, NULL);
>  }
>  
> -static unsigned long xen_save_fl(void)
> +asmlinkage unsigned long xen_save_fl(void)
>  {
>  	struct vcpu_info *vcpu;
>  	unsigned long flags;
> @@ -39,7 +39,7 @@ static unsigned long xen_save_fl(void)
>  }
>  PV_CALLEE_SAVE_REGS_THUNK(xen_save_fl);
>  
> -static void xen_restore_fl(unsigned long flags)
> +asmlinkage void xen_restore_fl(unsigned long flags)
>  {
>  	struct vcpu_info *vcpu;
>  
> @@ -66,7 +66,7 @@ static void xen_restore_fl(unsigned long flags)
>  }
>  PV_CALLEE_SAVE_REGS_THUNK(xen_restore_fl);
>  
> -static void xen_irq_disable(void)
> +asmlinkage void xen_irq_disable(void)
>  {
>  	/* There's a one instruction preempt window here.  We need to
>  	   make sure we're don't switch CPUs between getting the vcpu
> @@ -77,7 +77,7 @@ static void xen_irq_disable(void)
>  }
>  PV_CALLEE_SAVE_REGS_THUNK(xen_irq_disable);
>  
> -static void xen_irq_enable(void)
> +asmlinkage void xen_irq_enable(void)
>  {
>  	struct vcpu_info *vcpu;
>  
> diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
> index b65a761..9f82443 100644
> --- a/arch/x86/xen/mmu.c
> +++ b/arch/x86/xen/mmu.c
> @@ -429,7 +429,7 @@ static pteval_t iomap_pte(pteval_t val)
>  	return val;
>  }
>  
> -static pteval_t xen_pte_val(pte_t pte)
> +asmlinkage pteval_t xen_pte_val(pte_t pte)
>  {
>  	pteval_t pteval = pte.pte;
>  #if 0
> @@ -446,7 +446,7 @@ static pteval_t xen_pte_val(pte_t pte)
>  }
>  PV_CALLEE_SAVE_REGS_THUNK(xen_pte_val);
>  
> -static pgdval_t xen_pgd_val(pgd_t pgd)
> +asmlinkage pgdval_t xen_pgd_val(pgd_t pgd)
>  {
>  	return pte_mfn_to_pfn(pgd.pgd);
>  }
> @@ -477,7 +477,7 @@ void xen_set_pat(u64 pat)
>  	WARN_ON(pat != 0x0007010600070106ull);
>  }
>  
> -static pte_t xen_make_pte(pteval_t pte)
> +asmlinkage pte_t xen_make_pte(pteval_t pte)
>  {
>  	phys_addr_t addr = (pte & PTE_PFN_MASK);
>  #if 0
> @@ -512,14 +512,14 @@ static pte_t xen_make_pte(pteval_t pte)
>  }
>  PV_CALLEE_SAVE_REGS_THUNK(xen_make_pte);
>  
> -static pgd_t xen_make_pgd(pgdval_t pgd)
> +asmlinkage pgd_t xen_make_pgd(pgdval_t pgd)
>  {
>  	pgd = pte_pfn_to_mfn(pgd);
>  	return native_make_pgd(pgd);
>  }
>  PV_CALLEE_SAVE_REGS_THUNK(xen_make_pgd);
>  
> -static pmdval_t xen_pmd_val(pmd_t pmd)
> +asmlinkage pmdval_t xen_pmd_val(pmd_t pmd)
>  {
>  	return pte_mfn_to_pfn(pmd.pmd);
>  }
> @@ -578,7 +578,7 @@ static void xen_pmd_clear(pmd_t *pmdp)
>  }
>  #endif	/* CONFIG_X86_PAE */
>  
> -static pmd_t xen_make_pmd(pmdval_t pmd)
> +asmlinkage pmd_t xen_make_pmd(pmdval_t pmd)
>  {
>  	pmd = pte_pfn_to_mfn(pmd);
>  	return native_make_pmd(pmd);
> @@ -586,13 +586,13 @@ static pmd_t xen_make_pmd(pmdval_t pmd)
>  PV_CALLEE_SAVE_REGS_THUNK(xen_make_pmd);
>  
>  #if PAGETABLE_LEVELS == 4
> -static pudval_t xen_pud_val(pud_t pud)
> +asmlinkage pudval_t xen_pud_val(pud_t pud)
>  {
>  	return pte_mfn_to_pfn(pud.pud);
>  }
>  PV_CALLEE_SAVE_REGS_THUNK(xen_pud_val);
>  
> -static pud_t xen_make_pud(pudval_t pud)
> +asmlinkage pud_t xen_make_pud(pudval_t pud)
>  {
>  	pud = pte_pfn_to_mfn(pud);
>