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Message-Id: <20231210062138.2417-3-jgross@suse.com> Date: Sun, 10 Dec 2023 07:21:35 +0100 From: Juergen Gross <jgross@...e.com> To: linux-kernel@...r.kernel.org, x86@...nel.org, virtualization@...ts.linux.dev, kvm@...r.kernel.org Cc: Juergen Gross <jgross@...e.com>, Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>, "H. Peter Anvin" <hpa@...or.com>, Ajay Kaher <akaher@...are.com>, Alexey Makhalov <amakhalov@...are.com>, VMware PV-Drivers Reviewers <pv-drivers@...are.com>, Paolo Bonzini <pbonzini@...hat.com>, Wanpeng Li <wanpengli@...cent.com>, Vitaly Kuznetsov <vkuznets@...hat.com>, Boris Ostrovsky <boris.ostrovsky@...cle.com>, xen-devel@...ts.xenproject.org Subject: [PATCH v6 2/5] x86/paravirt: move some functions and defines to alternative As a preparation for replacing paravirt patching completely by alternative patching, move some backend functions and #defines to alternative code and header. Signed-off-by: Juergen Gross <jgross@...e.com> --- V4: - rename x86_nop() to nop_func() and x86_BUG() to BUG_func() (Boris Petkov) --- arch/x86/include/asm/alternative.h | 16 ++++++++++++ arch/x86/include/asm/paravirt.h | 12 --------- arch/x86/include/asm/paravirt_types.h | 4 +-- arch/x86/include/asm/qspinlock_paravirt.h | 4 +-- arch/x86/kernel/alternative.c | 10 ++++++++ arch/x86/kernel/kvm.c | 4 +-- arch/x86/kernel/paravirt.c | 30 +++++++---------------- arch/x86/xen/irq.c | 2 +- 8 files changed, 41 insertions(+), 41 deletions(-) diff --git a/arch/x86/include/asm/alternative.h b/arch/x86/include/asm/alternative.h index 65f79092c9d9..ce788ab4e77c 100644 --- a/arch/x86/include/asm/alternative.h +++ b/arch/x86/include/asm/alternative.h @@ -330,6 +330,22 @@ static inline int alternatives_text_reserved(void *start, void *end) */ #define ASM_NO_INPUT_CLOBBER(clbr...) "i" (0) : clbr +/* Macro for creating assembler functions avoiding any C magic. */ +#define DEFINE_ASM_FUNC(func, instr, sec) \ + asm (".pushsection " #sec ", \"ax\"\n" \ + ".global " #func "\n\t" \ + ".type " #func ", @function\n\t" \ + ASM_FUNC_ALIGN "\n" \ + #func ":\n\t" \ + ASM_ENDBR \ + instr "\n\t" \ + ASM_RET \ + ".size " #func ", . - " #func "\n\t" \ + ".popsection") + +void BUG_func(void); +void nop_func(void); + #else /* __ASSEMBLY__ */ #ifdef CONFIG_SMP diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h index aa76ac7c806c..f18bfa7f3070 100644 --- a/arch/x86/include/asm/paravirt.h +++ b/arch/x86/include/asm/paravirt.h @@ -720,18 +720,6 @@ static __always_inline unsigned long arch_local_irq_save(void) #undef PVOP_VCALL4 #undef PVOP_CALL4 -#define DEFINE_PARAVIRT_ASM(func, instr, sec) \ - asm (".pushsection " #sec ", \"ax\"\n" \ - ".global " #func "\n\t" \ - ".type " #func ", @function\n\t" \ - ASM_FUNC_ALIGN "\n" \ - #func ":\n\t" \ - ASM_ENDBR \ - instr "\n\t" \ - ASM_RET \ - ".size " #func ", . - " #func "\n\t" \ - ".popsection") - extern void default_banner(void); void native_pv_lock_init(void) __init; diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h index 483e19e5ca7a..166e9618158f 100644 --- a/arch/x86/include/asm/paravirt_types.h +++ b/arch/x86/include/asm/paravirt_types.h @@ -540,8 +540,6 @@ int paravirt_disable_iospace(void); __PVOP_VCALL(op, PVOP_CALL_ARG1(arg1), PVOP_CALL_ARG2(arg2), \ PVOP_CALL_ARG3(arg3), PVOP_CALL_ARG4(arg4)) -void _paravirt_nop(void); -void paravirt_BUG(void); unsigned long paravirt_ret0(void); #ifdef CONFIG_PARAVIRT_XXL u64 _paravirt_ident_64(u64); @@ -551,7 +549,7 @@ void pv_native_irq_enable(void); unsigned long pv_native_read_cr2(void); #endif -#define paravirt_nop ((void *)_paravirt_nop) +#define paravirt_nop ((void *)nop_func) extern struct paravirt_patch_site __parainstructions[], __parainstructions_end[]; diff --git a/arch/x86/include/asm/qspinlock_paravirt.h b/arch/x86/include/asm/qspinlock_paravirt.h index 85b6e3609cb9..ef9697f20129 100644 --- a/arch/x86/include/asm/qspinlock_paravirt.h +++ b/arch/x86/include/asm/qspinlock_paravirt.h @@ -56,8 +56,8 @@ __PV_CALLEE_SAVE_REGS_THUNK(__pv_queued_spin_unlock_slowpath, ".spinlock.text"); "pop %rdx\n\t" \ FRAME_END -DEFINE_PARAVIRT_ASM(__raw_callee_save___pv_queued_spin_unlock, - PV_UNLOCK_ASM, .spinlock.text); +DEFINE_ASM_FUNC(__raw_callee_save___pv_queued_spin_unlock, + PV_UNLOCK_ASM, .spinlock.text); #else /* CONFIG_64BIT */ diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index be35c8ccf826..ca25dd280b8c 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -385,6 +385,16 @@ apply_relocation(u8 *buf, size_t len, u8 *dest, u8 *src, size_t src_len) } } +/* Low-level backend functions usable from alternative code replacements. */ +DEFINE_ASM_FUNC(nop_func, "", .entry.text); +EXPORT_SYMBOL_GPL(nop_func); + +noinstr void BUG_func(void) +{ + BUG(); +} +EXPORT_SYMBOL_GPL(BUG_func); + /* * Replace instructions with better alternatives for this CPU type. This runs * before SMP is initialized to avoid SMP problems with self modifying code. diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c index 0ddb3bd0f1aa..c461c1a4b6af 100644 --- a/arch/x86/kernel/kvm.c +++ b/arch/x86/kernel/kvm.c @@ -803,8 +803,8 @@ extern bool __raw_callee_save___kvm_vcpu_is_preempted(long); "cmpb $0, " __stringify(KVM_STEAL_TIME_preempted) "+steal_time(%rax)\n\t" \ "setne %al\n\t" -DEFINE_PARAVIRT_ASM(__raw_callee_save___kvm_vcpu_is_preempted, - PV_VCPU_PREEMPTED_ASM, .text); +DEFINE_ASM_FUNC(__raw_callee_save___kvm_vcpu_is_preempted, + PV_VCPU_PREEMPTED_ASM, .text); #endif static void __init kvm_guest_init(void) diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c index 97f1436c1a20..acc5b1004f0f 100644 --- a/arch/x86/kernel/paravirt.c +++ b/arch/x86/kernel/paravirt.c @@ -34,14 +34,8 @@ #include <asm/io_bitmap.h> #include <asm/gsseg.h> -/* - * nop stub, which must not clobber anything *including the stack* to - * avoid confusing the entry prologues. - */ -DEFINE_PARAVIRT_ASM(_paravirt_nop, "", .entry.text); - /* stub always returning 0. */ -DEFINE_PARAVIRT_ASM(paravirt_ret0, "xor %eax,%eax", .entry.text); +DEFINE_ASM_FUNC(paravirt_ret0, "xor %eax,%eax", .entry.text); void __init default_banner(void) { @@ -49,12 +43,6 @@ void __init default_banner(void) pv_info.name); } -/* Undefined instruction for dealing with missing ops pointers. */ -noinstr void paravirt_BUG(void) -{ - BUG(); -} - static unsigned paravirt_patch_call(void *insn_buff, const void *target, unsigned long addr, unsigned len) { @@ -64,11 +52,11 @@ static unsigned paravirt_patch_call(void *insn_buff, const void *target, } #ifdef CONFIG_PARAVIRT_XXL -DEFINE_PARAVIRT_ASM(_paravirt_ident_64, "mov %rdi, %rax", .text); -DEFINE_PARAVIRT_ASM(pv_native_save_fl, "pushf; pop %rax", .noinstr.text); -DEFINE_PARAVIRT_ASM(pv_native_irq_disable, "cli", .noinstr.text); -DEFINE_PARAVIRT_ASM(pv_native_irq_enable, "sti", .noinstr.text); -DEFINE_PARAVIRT_ASM(pv_native_read_cr2, "mov %cr2, %rax", .noinstr.text); +DEFINE_ASM_FUNC(_paravirt_ident_64, "mov %rdi, %rax", .text); +DEFINE_ASM_FUNC(pv_native_save_fl, "pushf; pop %rax", .noinstr.text); +DEFINE_ASM_FUNC(pv_native_irq_disable, "cli", .noinstr.text); +DEFINE_ASM_FUNC(pv_native_irq_enable, "sti", .noinstr.text); +DEFINE_ASM_FUNC(pv_native_read_cr2, "mov %cr2, %rax", .noinstr.text); #endif DEFINE_STATIC_KEY_TRUE(virt_spin_lock_key); @@ -96,9 +84,9 @@ unsigned int paravirt_patch(u8 type, void *insn_buff, unsigned long addr, unsigned ret; if (opfunc == NULL) - /* If there's no function, patch it with paravirt_BUG() */ - ret = paravirt_patch_call(insn_buff, paravirt_BUG, addr, len); - else if (opfunc == _paravirt_nop) + /* If there's no function, patch it with BUG_func() */ + ret = paravirt_patch_call(insn_buff, BUG_func, addr, len); + else if (opfunc == nop_func) ret = 0; else /* Otherwise call the function. */ diff --git a/arch/x86/xen/irq.c b/arch/x86/xen/irq.c index 6092fea7d651..39982f955cfe 100644 --- a/arch/x86/xen/irq.c +++ b/arch/x86/xen/irq.c @@ -45,7 +45,7 @@ static const typeof(pv_ops) xen_irq_ops __initconst = { /* Initial interrupt flag handling only called while interrupts off. */ .save_fl = __PV_IS_CALLEE_SAVE(paravirt_ret0), .irq_disable = __PV_IS_CALLEE_SAVE(paravirt_nop), - .irq_enable = __PV_IS_CALLEE_SAVE(paravirt_BUG), + .irq_enable = __PV_IS_CALLEE_SAVE(BUG_func), .safe_halt = xen_safe_halt, .halt = xen_halt, -- 2.35.3
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