[PATCH 05/17] x86/tsc/paravirt: Remove the read_tsc and read_tscp paravirt hooks

From: Andy Lutomirski
Date: Fri Jun 12 2015 - 19:52:23 EST


We've had read_tsc and read_tscp paravirt hooks since the very
beginning of paravirt, i.e., d3561b7fa0fb ("[PATCH] paravirt: header
and stubs for paravirtualisation"). AFAICT the only paravirt guest
implementation that ever replaced these calls was vmware, and it's
gone. Arguably even vmware shouldn't have hooked rdtsc -- we fully
support systems that don't have a TSC at all, so there's no point
for a paravirt implementation to pretend that we have a TSC but to
replace it.

I also doubt that these hooks actually worked. Note that the only
paravirt_read_tsc caller was rdtscl.

Just remove them. If anyone ever needs them again, they can try
to make a case for why they need them.

Before, on a paravirt config:
text data bss dec hex filename
13426505 1827056 14508032 29761593 1c62039 vmlinux

After:
text data bss dec hex filename
13426617 1827056 14508032 29761705 1c620a9 vmlinux

Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx>
---
arch/x86/include/asm/msr.h | 8 +++++---
arch/x86/include/asm/paravirt.h | 16 ----------------
arch/x86/include/asm/paravirt_types.h | 2 --
arch/x86/kernel/paravirt.c | 2 --
arch/x86/kernel/paravirt_patch_32.c | 2 --
arch/x86/xen/enlighten.c | 3 ---
6 files changed, 5 insertions(+), 28 deletions(-)

diff --git a/arch/x86/include/asm/msr.h b/arch/x86/include/asm/msr.h
index 8612b0086933..6427c9cb9540 100644
--- a/arch/x86/include/asm/msr.h
+++ b/arch/x86/include/asm/msr.h
@@ -178,9 +178,6 @@ static inline int rdmsrl_safe(unsigned msr, unsigned long long *p)
return err;
}

-#define rdtscl(low) \
- ((low) = (u32)native_read_tsc())
-
#define rdpmc(counter, low, high) \
do { \
u64 _l = native_read_pmc((counter)); \
@@ -192,6 +189,11 @@ do { \


#endif /* !CONFIG_PARAVIRT */
+
+#define rdtscl(low) \
+ ((low) = (u32)native_read_tsc())
+
+
/*
* 64-bit version of wrmsr_safe():
*/
diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
index a5de6bd8abcc..c2be0375bcad 100644
--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -174,17 +174,6 @@ static inline int rdmsrl_safe(unsigned msr, unsigned long long *p)
return err;
}

-static inline u64 paravirt_read_tsc(void)
-{
- return PVOP_CALL0(u64, pv_cpu_ops.read_tsc);
-}
-
-#define rdtscl(low) \
-do { \
- u64 _l = paravirt_read_tsc(); \
- low = (int)_l; \
-} while (0)
-
static inline unsigned long long paravirt_sched_clock(void)
{
return PVOP_CALL0(unsigned long long, pv_time_ops.sched_clock);
@@ -213,11 +202,6 @@ do { \

#define rdpmcl(counter, val) ((val) = paravirt_read_pmc(counter))

-static inline unsigned long long paravirt_rdtscp(unsigned int *aux)
-{
- return PVOP_CALL1(u64, pv_cpu_ops.read_tscp, aux);
-}
-
static inline void paravirt_alloc_ldt(struct desc_struct *ldt, unsigned entries)
{
PVOP_VCALL2(pv_cpu_ops.alloc_ldt, ldt, entries);
diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h
index a6b8f9fadb06..ce029e4fa7c6 100644
--- a/arch/x86/include/asm/paravirt_types.h
+++ b/arch/x86/include/asm/paravirt_types.h
@@ -156,9 +156,7 @@ struct pv_cpu_ops {
u64 (*read_msr)(unsigned int msr, int *err);
int (*write_msr)(unsigned int msr, unsigned low, unsigned high);

- u64 (*read_tsc)(void);
u64 (*read_pmc)(int counter);
- unsigned long long (*read_tscp)(unsigned int *aux);

#ifdef CONFIG_X86_32
/*
diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
index 58bcfb67c01f..f68e48f5f6c2 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -351,9 +351,7 @@ __visible struct pv_cpu_ops pv_cpu_ops = {
.wbinvd = native_wbinvd,
.read_msr = native_read_msr_safe,
.write_msr = native_write_msr_safe,
- .read_tsc = native_read_tsc,
.read_pmc = native_read_pmc,
- .read_tscp = native_read_tscp,
.load_tr_desc = native_load_tr_desc,
.set_ldt = native_set_ldt,
.load_gdt = native_load_gdt,
diff --git a/arch/x86/kernel/paravirt_patch_32.c b/arch/x86/kernel/paravirt_patch_32.c
index e1b013696dde..c89f50a76e97 100644
--- a/arch/x86/kernel/paravirt_patch_32.c
+++ b/arch/x86/kernel/paravirt_patch_32.c
@@ -10,7 +10,6 @@ DEF_NATIVE(pv_mmu_ops, read_cr2, "mov %cr2, %eax");
DEF_NATIVE(pv_mmu_ops, write_cr3, "mov %eax, %cr3");
DEF_NATIVE(pv_mmu_ops, read_cr3, "mov %cr3, %eax");
DEF_NATIVE(pv_cpu_ops, clts, "clts");
-DEF_NATIVE(pv_cpu_ops, read_tsc, "rdtsc");

#if defined(CONFIG_PARAVIRT_SPINLOCKS) && defined(CONFIG_QUEUED_SPINLOCKS)
DEF_NATIVE(pv_lock_ops, queued_spin_unlock, "movb $0, (%eax)");
@@ -52,7 +51,6 @@ unsigned native_patch(u8 type, u16 clobbers, void *ibuf,
PATCH_SITE(pv_mmu_ops, read_cr3);
PATCH_SITE(pv_mmu_ops, write_cr3);
PATCH_SITE(pv_cpu_ops, clts);
- PATCH_SITE(pv_cpu_ops, read_tsc);
#if defined(CONFIG_PARAVIRT_SPINLOCKS) && defined(CONFIG_QUEUED_SPINLOCKS)
case PARAVIRT_PATCH(pv_lock_ops.queued_spin_unlock):
if (pv_is_native_spin_unlock()) {
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 0b95c9b8283f..32136bfca43f 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1175,11 +1175,8 @@ static const struct pv_cpu_ops xen_cpu_ops __initconst = {
.read_msr = xen_read_msr_safe,
.write_msr = xen_write_msr_safe,

- .read_tsc = native_read_tsc,
.read_pmc = native_read_pmc,

- .read_tscp = native_read_tscp,
-
.iret = xen_iret,
#ifdef CONFIG_X86_64
.usergs_sysret32 = xen_sysret32,
--
2.4.2

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