| Message ID | 20221020091950.6741-1-jgross@suse.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | x86/paravirt: use common macro for creating simple asm paravirt functions | expand |
Ping? On 20.10.22 11:19, Juergen Gross wrote: > There are some paravirt assembler functions which are sharing a common > pattern. Introduce a macro DEFINE_PARAVIRT_ASM() for creating them. > > The explicit _paravirt_nop() prototype in paravirt.c isn't needed, as > it is included in paravirt_types.h already. > > Signed-off-by: Juergen Gross <jgross@suse.com> > --- > arch/x86/include/asm/paravirt.h | 12 ++++++ > arch/x86/include/asm/qspinlock_paravirt.h | 46 ++++++++++------------- > arch/x86/kernel/kvm.c | 19 +++------- > arch/x86/kernel/paravirt.c | 22 ++--------- > 4 files changed, 40 insertions(+), 59 deletions(-) > > diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h > index 2a0b8dd4ec33..479bf264b8aa 100644 > --- a/arch/x86/include/asm/paravirt.h > +++ b/arch/x86/include/asm/paravirt.h > @@ -730,6 +730,18 @@ 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" \ > + __ALIGN_STR "\n" \ > + #func ":\n\t" \ > + ASM_ENDBR \ > + instr \ > + ASM_RET \ > + ".size " #func ", . - " #func "\n\t" \ > + ".popsection") > + > extern void default_banner(void); > > #else /* __ASSEMBLY__ */ > diff --git a/arch/x86/include/asm/qspinlock_paravirt.h b/arch/x86/include/asm/qspinlock_paravirt.h > index 60ece592b220..c490f5eb9f3e 100644 > --- a/arch/x86/include/asm/qspinlock_paravirt.h > +++ b/arch/x86/include/asm/qspinlock_paravirt.h > @@ -14,8 +14,6 @@ > > __PV_CALLEE_SAVE_REGS_THUNK(__pv_queued_spin_unlock_slowpath, ".spinlock.text"); > #define __pv_queued_spin_unlock __pv_queued_spin_unlock > -#define PV_UNLOCK "__raw_callee_save___pv_queued_spin_unlock" > -#define PV_UNLOCK_SLOWPATH "__raw_callee_save___pv_queued_spin_unlock_slowpath" > > /* > * Optimized assembly version of __raw_callee_save___pv_queued_spin_unlock > @@ -37,32 +35,26 @@ __PV_CALLEE_SAVE_REGS_THUNK(__pv_queued_spin_unlock_slowpath, ".spinlock.text"); > * rsi = lockval (second argument) > * rdx = internal variable (set to 0) > */ > -asm (".pushsection .spinlock.text;" > - ".globl " PV_UNLOCK ";" > - ".type " PV_UNLOCK ", @function;" > - ".align 4,0x90;" > - PV_UNLOCK ": " > - ASM_ENDBR > - FRAME_BEGIN > - "push %rdx;" > - "mov $0x1,%eax;" > - "xor %edx,%edx;" > - LOCK_PREFIX "cmpxchg %dl,(%rdi);" > - "cmp $0x1,%al;" > - "jne .slowpath;" > - "pop %rdx;" > +#define PV_UNLOCK_ASM \ > + FRAME_BEGIN \ > + "push %rdx\n\t" \ > + "mov $0x1,%eax\n\t" \ > + "xor %edx,%edx\n\t" \ > + LOCK_PREFIX "cmpxchg %dl,(%rdi)\n\t" \ > + "cmp $0x1,%al\n\t" \ > + "jne .slowpath\n\t" \ > + "pop %rdx\n\t" \ > + FRAME_END \ > + ASM_RET \ > + ".slowpath:\n\t" \ > + "push %rsi\n\t" \ > + "movzbl %al,%esi\n\t" \ > + "call __raw_callee_save___pv_queued_spin_unlock_slowpath\n\t" \ > + "pop %rsi\n\t" \ > + "pop %rdx\n\t" \ > FRAME_END > - ASM_RET > - ".slowpath: " > - "push %rsi;" > - "movzbl %al,%esi;" > - "call " PV_UNLOCK_SLOWPATH ";" > - "pop %rsi;" > - "pop %rdx;" > - FRAME_END > - ASM_RET > - ".size " PV_UNLOCK ", .-" PV_UNLOCK ";" > - ".popsection"); > +DEFINE_PARAVIRT_ASM(__raw_callee_save___pv_queued_spin_unlock, PV_UNLOCK_ASM, > + .spinlock.text); > > #else /* CONFIG_64BIT */ > > diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c > index d4e48b4a438b..856708cc78e7 100644 > --- a/arch/x86/kernel/kvm.c > +++ b/arch/x86/kernel/kvm.c > @@ -798,19 +798,12 @@ extern bool __raw_callee_save___kvm_vcpu_is_preempted(long); > * Hand-optimize version for x86-64 to avoid 8 64-bit register saving and > * restoring to/from the stack. > */ > -asm( > -".pushsection .text;" > -".global __raw_callee_save___kvm_vcpu_is_preempted;" > -".type __raw_callee_save___kvm_vcpu_is_preempted, @function;" > -"__raw_callee_save___kvm_vcpu_is_preempted:" > -ASM_ENDBR > -"movq __per_cpu_offset(,%rdi,8), %rax;" > -"cmpb $0, " __stringify(KVM_STEAL_TIME_preempted) "+steal_time(%rax);" > -"setne %al;" > -ASM_RET > -".size __raw_callee_save___kvm_vcpu_is_preempted, .-__raw_callee_save___kvm_vcpu_is_preempted;" > -".popsection"); > - > +#define PV_VCPU_PREEMPTED_ASM \ > + "movq __per_cpu_offset(,%rdi,8), %rax\n\t" \ > + "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); > #endif > > static void __init kvm_guest_init(void) > diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c > index 7ca2d46c08cc..6f306f885caf 100644 > --- a/arch/x86/kernel/paravirt.c > +++ b/arch/x86/kernel/paravirt.c > @@ -37,27 +37,11 @@ > * nop stub, which must not clobber anything *including the stack* to > * avoid confusing the entry prologues. > */ > -extern void _paravirt_nop(void); > -asm (".pushsection .entry.text, \"ax\"\n" > - ".global _paravirt_nop\n" > - "_paravirt_nop:\n\t" > - ASM_ENDBR > - ASM_RET > - ".size _paravirt_nop, . - _paravirt_nop\n\t" > - ".type _paravirt_nop, @function\n\t" > - ".popsection"); > +DEFINE_PARAVIRT_ASM(_paravirt_nop, "", .entry.text); > > /* stub always returning 0. */ > -asm (".pushsection .entry.text, \"ax\"\n" > - ".global paravirt_ret0\n" > - "paravirt_ret0:\n\t" > - ASM_ENDBR > - "xor %" _ASM_AX ", %" _ASM_AX ";\n\t" > - ASM_RET > - ".size paravirt_ret0, . - paravirt_ret0\n\t" > - ".type paravirt_ret0, @function\n\t" > - ".popsection"); > - > +#define PV_RET0_ASM "xor %" _ASM_AX ", %" _ASM_AX "\n\t" > +DEFINE_PARAVIRT_ASM(paravirt_ret0, PV_RET0_ASM, .entry.text); > > void __init default_banner(void) > {
Hi Juergen, Sorry for the delay in reviewing this patch! On 10/20/22 2:19 AM, Juergen Gross wrote: > There are some paravirt assembler functions which are sharing a common > pattern. Introduce a macro DEFINE_PARAVIRT_ASM() for creating them. > > The explicit _paravirt_nop() prototype in paravirt.c isn't needed, as > it is included in paravirt_types.h already. > > Signed-off-by: Juergen Gross <jgross@suse.com> I just wanted to make a note that the part of this patch that's not purely cleanup is the addition of the alignment (__ALIGN_STR) to __raw_callee_save___kvm_vcpu_is_preempted(), _paravirt_nop() and paravirt_ret0(). Maybe that's worth calling out in the commit message? Reviewed-by: Srivatsa S. Bhat (VMware) <srivatsa@csail.mit.edu> Regards, Srivatsa VMware Photon OS > --- > arch/x86/include/asm/paravirt.h | 12 ++++++ > arch/x86/include/asm/qspinlock_paravirt.h | 46 ++++++++++------------- > arch/x86/kernel/kvm.c | 19 +++------- > arch/x86/kernel/paravirt.c | 22 ++--------- > 4 files changed, 40 insertions(+), 59 deletions(-) > > diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h > index 2a0b8dd4ec33..479bf264b8aa 100644 > --- a/arch/x86/include/asm/paravirt.h > +++ b/arch/x86/include/asm/paravirt.h > @@ -730,6 +730,18 @@ 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" \ > + __ALIGN_STR "\n" \ > + #func ":\n\t" \ > + ASM_ENDBR \ > + instr \ > + ASM_RET \ > + ".size " #func ", . - " #func "\n\t" \ > + ".popsection") > + > extern void default_banner(void); > > #else /* __ASSEMBLY__ */ > diff --git a/arch/x86/include/asm/qspinlock_paravirt.h b/arch/x86/include/asm/qspinlock_paravirt.h > index 60ece592b220..c490f5eb9f3e 100644 > --- a/arch/x86/include/asm/qspinlock_paravirt.h > +++ b/arch/x86/include/asm/qspinlock_paravirt.h > @@ -14,8 +14,6 @@ > > __PV_CALLEE_SAVE_REGS_THUNK(__pv_queued_spin_unlock_slowpath, ".spinlock.text"); > #define __pv_queued_spin_unlock __pv_queued_spin_unlock > -#define PV_UNLOCK "__raw_callee_save___pv_queued_spin_unlock" > -#define PV_UNLOCK_SLOWPATH "__raw_callee_save___pv_queued_spin_unlock_slowpath" > > /* > * Optimized assembly version of __raw_callee_save___pv_queued_spin_unlock > @@ -37,32 +35,26 @@ __PV_CALLEE_SAVE_REGS_THUNK(__pv_queued_spin_unlock_slowpath, ".spinlock.text"); > * rsi = lockval (second argument) > * rdx = internal variable (set to 0) > */ > -asm (".pushsection .spinlock.text;" > - ".globl " PV_UNLOCK ";" > - ".type " PV_UNLOCK ", @function;" > - ".align 4,0x90;" > - PV_UNLOCK ": " > - ASM_ENDBR > - FRAME_BEGIN > - "push %rdx;" > - "mov $0x1,%eax;" > - "xor %edx,%edx;" > - LOCK_PREFIX "cmpxchg %dl,(%rdi);" > - "cmp $0x1,%al;" > - "jne .slowpath;" > - "pop %rdx;" > +#define PV_UNLOCK_ASM \ > + FRAME_BEGIN \ > + "push %rdx\n\t" \ > + "mov $0x1,%eax\n\t" \ > + "xor %edx,%edx\n\t" \ > + LOCK_PREFIX "cmpxchg %dl,(%rdi)\n\t" \ > + "cmp $0x1,%al\n\t" \ > + "jne .slowpath\n\t" \ > + "pop %rdx\n\t" \ > + FRAME_END \ > + ASM_RET \ > + ".slowpath:\n\t" \ > + "push %rsi\n\t" \ > + "movzbl %al,%esi\n\t" \ > + "call __raw_callee_save___pv_queued_spin_unlock_slowpath\n\t" \ > + "pop %rsi\n\t" \ > + "pop %rdx\n\t" \ > FRAME_END > - ASM_RET > - ".slowpath: " > - "push %rsi;" > - "movzbl %al,%esi;" > - "call " PV_UNLOCK_SLOWPATH ";" > - "pop %rsi;" > - "pop %rdx;" > - FRAME_END > - ASM_RET > - ".size " PV_UNLOCK ", .-" PV_UNLOCK ";" > - ".popsection"); > +DEFINE_PARAVIRT_ASM(__raw_callee_save___pv_queued_spin_unlock, PV_UNLOCK_ASM, > + .spinlock.text); > > #else /* CONFIG_64BIT */ > > diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c > index d4e48b4a438b..856708cc78e7 100644 > --- a/arch/x86/kernel/kvm.c > +++ b/arch/x86/kernel/kvm.c > @@ -798,19 +798,12 @@ extern bool __raw_callee_save___kvm_vcpu_is_preempted(long); > * Hand-optimize version for x86-64 to avoid 8 64-bit register saving and > * restoring to/from the stack. > */ > -asm( > -".pushsection .text;" > -".global __raw_callee_save___kvm_vcpu_is_preempted;" > -".type __raw_callee_save___kvm_vcpu_is_preempted, @function;" > -"__raw_callee_save___kvm_vcpu_is_preempted:" > -ASM_ENDBR > -"movq __per_cpu_offset(,%rdi,8), %rax;" > -"cmpb $0, " __stringify(KVM_STEAL_TIME_preempted) "+steal_time(%rax);" > -"setne %al;" > -ASM_RET > -".size __raw_callee_save___kvm_vcpu_is_preempted, .-__raw_callee_save___kvm_vcpu_is_preempted;" > -".popsection"); > - > +#define PV_VCPU_PREEMPTED_ASM \ > + "movq __per_cpu_offset(,%rdi,8), %rax\n\t" \ > + "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); > #endif > > static void __init kvm_guest_init(void) > diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c > index 7ca2d46c08cc..6f306f885caf 100644 > --- a/arch/x86/kernel/paravirt.c > +++ b/arch/x86/kernel/paravirt.c > @@ -37,27 +37,11 @@ > * nop stub, which must not clobber anything *including the stack* to > * avoid confusing the entry prologues. > */ > -extern void _paravirt_nop(void); > -asm (".pushsection .entry.text, \"ax\"\n" > - ".global _paravirt_nop\n" > - "_paravirt_nop:\n\t" > - ASM_ENDBR > - ASM_RET > - ".size _paravirt_nop, . - _paravirt_nop\n\t" > - ".type _paravirt_nop, @function\n\t" > - ".popsection"); > +DEFINE_PARAVIRT_ASM(_paravirt_nop, "", .entry.text); > > /* stub always returning 0. */ > -asm (".pushsection .entry.text, \"ax\"\n" > - ".global paravirt_ret0\n" > - "paravirt_ret0:\n\t" > - ASM_ENDBR > - "xor %" _ASM_AX ", %" _ASM_AX ";\n\t" > - ASM_RET > - ".size paravirt_ret0, . - paravirt_ret0\n\t" > - ".type paravirt_ret0, @function\n\t" > - ".popsection"); > - > +#define PV_RET0_ASM "xor %" _ASM_AX ", %" _ASM_AX "\n\t" > +DEFINE_PARAVIRT_ASM(paravirt_ret0, PV_RET0_ASM, .entry.text); > > void __init default_banner(void) > { >
On 09.11.22 06:16, Srivatsa S. Bhat wrote: > Hi Juergen, > > Sorry for the delay in reviewing this patch! > > On 10/20/22 2:19 AM, Juergen Gross wrote: >> There are some paravirt assembler functions which are sharing a common >> pattern. Introduce a macro DEFINE_PARAVIRT_ASM() for creating them. >> >> The explicit _paravirt_nop() prototype in paravirt.c isn't needed, as >> it is included in paravirt_types.h already. >> >> Signed-off-by: Juergen Gross <jgross@suse.com> > > I just wanted to make a note that the part of this patch that's not > purely cleanup is the addition of the alignment (__ALIGN_STR) to > __raw_callee_save___kvm_vcpu_is_preempted(), _paravirt_nop() and > paravirt_ret0(). Maybe that's worth calling out in the commit message? I can do that. > > Reviewed-by: Srivatsa S. Bhat (VMware) <srivatsa@csail.mit.edu> Thanks, Juergen
diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h index 2a0b8dd4ec33..479bf264b8aa 100644 --- a/arch/x86/include/asm/paravirt.h +++ b/arch/x86/include/asm/paravirt.h @@ -730,6 +730,18 @@ 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" \ + __ALIGN_STR "\n" \ + #func ":\n\t" \ + ASM_ENDBR \ + instr \ + ASM_RET \ + ".size " #func ", . - " #func "\n\t" \ + ".popsection") + extern void default_banner(void); #else /* __ASSEMBLY__ */ diff --git a/arch/x86/include/asm/qspinlock_paravirt.h b/arch/x86/include/asm/qspinlock_paravirt.h index 60ece592b220..c490f5eb9f3e 100644 --- a/arch/x86/include/asm/qspinlock_paravirt.h +++ b/arch/x86/include/asm/qspinlock_paravirt.h @@ -14,8 +14,6 @@ __PV_CALLEE_SAVE_REGS_THUNK(__pv_queued_spin_unlock_slowpath, ".spinlock.text"); #define __pv_queued_spin_unlock __pv_queued_spin_unlock -#define PV_UNLOCK "__raw_callee_save___pv_queued_spin_unlock" -#define PV_UNLOCK_SLOWPATH "__raw_callee_save___pv_queued_spin_unlock_slowpath" /* * Optimized assembly version of __raw_callee_save___pv_queued_spin_unlock @@ -37,32 +35,26 @@ __PV_CALLEE_SAVE_REGS_THUNK(__pv_queued_spin_unlock_slowpath, ".spinlock.text"); * rsi = lockval (second argument) * rdx = internal variable (set to 0) */ -asm (".pushsection .spinlock.text;" - ".globl " PV_UNLOCK ";" - ".type " PV_UNLOCK ", @function;" - ".align 4,0x90;" - PV_UNLOCK ": " - ASM_ENDBR - FRAME_BEGIN - "push %rdx;" - "mov $0x1,%eax;" - "xor %edx,%edx;" - LOCK_PREFIX "cmpxchg %dl,(%rdi);" - "cmp $0x1,%al;" - "jne .slowpath;" - "pop %rdx;" +#define PV_UNLOCK_ASM \ + FRAME_BEGIN \ + "push %rdx\n\t" \ + "mov $0x1,%eax\n\t" \ + "xor %edx,%edx\n\t" \ + LOCK_PREFIX "cmpxchg %dl,(%rdi)\n\t" \ + "cmp $0x1,%al\n\t" \ + "jne .slowpath\n\t" \ + "pop %rdx\n\t" \ + FRAME_END \ + ASM_RET \ + ".slowpath:\n\t" \ + "push %rsi\n\t" \ + "movzbl %al,%esi\n\t" \ + "call __raw_callee_save___pv_queued_spin_unlock_slowpath\n\t" \ + "pop %rsi\n\t" \ + "pop %rdx\n\t" \ FRAME_END - ASM_RET - ".slowpath: " - "push %rsi;" - "movzbl %al,%esi;" - "call " PV_UNLOCK_SLOWPATH ";" - "pop %rsi;" - "pop %rdx;" - FRAME_END - ASM_RET - ".size " PV_UNLOCK ", .-" PV_UNLOCK ";" - ".popsection"); +DEFINE_PARAVIRT_ASM(__raw_callee_save___pv_queued_spin_unlock, PV_UNLOCK_ASM, + .spinlock.text); #else /* CONFIG_64BIT */ diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c index d4e48b4a438b..856708cc78e7 100644 --- a/arch/x86/kernel/kvm.c +++ b/arch/x86/kernel/kvm.c @@ -798,19 +798,12 @@ extern bool __raw_callee_save___kvm_vcpu_is_preempted(long); * Hand-optimize version for x86-64 to avoid 8 64-bit register saving and * restoring to/from the stack. */ -asm( -".pushsection .text;" -".global __raw_callee_save___kvm_vcpu_is_preempted;" -".type __raw_callee_save___kvm_vcpu_is_preempted, @function;" -"__raw_callee_save___kvm_vcpu_is_preempted:" -ASM_ENDBR -"movq __per_cpu_offset(,%rdi,8), %rax;" -"cmpb $0, " __stringify(KVM_STEAL_TIME_preempted) "+steal_time(%rax);" -"setne %al;" -ASM_RET -".size __raw_callee_save___kvm_vcpu_is_preempted, .-__raw_callee_save___kvm_vcpu_is_preempted;" -".popsection"); - +#define PV_VCPU_PREEMPTED_ASM \ + "movq __per_cpu_offset(,%rdi,8), %rax\n\t" \ + "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); #endif static void __init kvm_guest_init(void) diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c index 7ca2d46c08cc..6f306f885caf 100644 --- a/arch/x86/kernel/paravirt.c +++ b/arch/x86/kernel/paravirt.c @@ -37,27 +37,11 @@ * nop stub, which must not clobber anything *including the stack* to * avoid confusing the entry prologues. */ -extern void _paravirt_nop(void); -asm (".pushsection .entry.text, \"ax\"\n" - ".global _paravirt_nop\n" - "_paravirt_nop:\n\t" - ASM_ENDBR - ASM_RET - ".size _paravirt_nop, . - _paravirt_nop\n\t" - ".type _paravirt_nop, @function\n\t" - ".popsection"); +DEFINE_PARAVIRT_ASM(_paravirt_nop, "", .entry.text); /* stub always returning 0. */ -asm (".pushsection .entry.text, \"ax\"\n" - ".global paravirt_ret0\n" - "paravirt_ret0:\n\t" - ASM_ENDBR - "xor %" _ASM_AX ", %" _ASM_AX ";\n\t" - ASM_RET - ".size paravirt_ret0, . - paravirt_ret0\n\t" - ".type paravirt_ret0, @function\n\t" - ".popsection"); - +#define PV_RET0_ASM "xor %" _ASM_AX ", %" _ASM_AX "\n\t" +DEFINE_PARAVIRT_ASM(paravirt_ret0, PV_RET0_ASM, .entry.text); void __init default_banner(void) {
There are some paravirt assembler functions which are sharing a common pattern. Introduce a macro DEFINE_PARAVIRT_ASM() for creating them. The explicit _paravirt_nop() prototype in paravirt.c isn't needed, as it is included in paravirt_types.h already. Signed-off-by: Juergen Gross <jgross@suse.com> --- arch/x86/include/asm/paravirt.h | 12 ++++++ arch/x86/include/asm/qspinlock_paravirt.h | 46 ++++++++++------------- arch/x86/kernel/kvm.c | 19 +++------- arch/x86/kernel/paravirt.c | 22 ++--------- 4 files changed, 40 insertions(+), 59 deletions(-)