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[PATCH v2 05/13] perf: Force architectures to opt-in to guest callbacks



Introduce HAVE_GUEST_PERF_EVENTS and require architectures to select it
to allow registering guest callbacks in perf.  Future patches will convert
the callbacks to static_call.  Rather than churn a bunch of arch code (that
was presumably copy+pasted from x86), remove it wholesale as it's useless
and at best wasting cycles.

Wrap even the stubs with an #ifdef to avoid an arch sneaking in a bogus
registration with CONFIG_PERF_EVENTS=n.

Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
 arch/arm/kernel/perf_callchain.c   | 33 ++++-------------------------
 arch/arm64/Kconfig                 |  1 +
 arch/csky/kernel/perf_callchain.c  | 12 -----------
 arch/nds32/kernel/perf_event_cpu.c | 34 ++++--------------------------
 arch/riscv/kernel/perf_callchain.c | 13 ------------
 arch/x86/Kconfig                   |  1 +
 include/linux/perf_event.h         |  4 ++++
 init/Kconfig                       |  3 +++
 kernel/events/core.c               |  2 ++
 9 files changed, 19 insertions(+), 84 deletions(-)

diff --git a/arch/arm/kernel/perf_callchain.c b/arch/arm/kernel/perf_callchain.c
index 1626dfc6f6ce..bc6b246ab55e 100644
--- a/arch/arm/kernel/perf_callchain.c
+++ b/arch/arm/kernel/perf_callchain.c
@@ -62,14 +62,8 @@ user_backtrace(struct frame_tail __user *tail,
 void
 perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs 
*regs)
 {
-       struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
        struct frame_tail __user *tail;
 
-       if (guest_cbs && guest_cbs->is_in_guest()) {
-               /* We don't support guest os callchain now */
-               return;
-       }
-
        perf_callchain_store(entry, regs->ARM_pc);
 
        if (!current->mm)
@@ -99,44 +93,25 @@ callchain_trace(struct stackframe *fr,
 void
 perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs 
*regs)
 {
-       struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
        struct stackframe fr;
 
-       if (guest_cbs && guest_cbs->is_in_guest()) {
-               /* We don't support guest os callchain now */
-               return;
-       }
-
        arm_get_current_stackframe(regs, &fr);
        walk_stackframe(&fr, callchain_trace, entry);
 }
 
 unsigned long perf_instruction_pointer(struct pt_regs *regs)
 {
-       struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
-
-       if (guest_cbs && guest_cbs->is_in_guest())
-               return guest_cbs->get_guest_ip();
-
        return instruction_pointer(regs);
 }
 
 unsigned long perf_misc_flags(struct pt_regs *regs)
 {
-       struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
        int misc = 0;
 
-       if (guest_cbs && guest_cbs->is_in_guest()) {
-               if (guest_cbs->is_user_mode())
-                       misc |= PERF_RECORD_MISC_GUEST_USER;
-               else
-                       misc |= PERF_RECORD_MISC_GUEST_KERNEL;
-       } else {
-               if (user_mode(regs))
-                       misc |= PERF_RECORD_MISC_USER;
-               else
-                       misc |= PERF_RECORD_MISC_KERNEL;
-       }
+       if (user_mode(regs))
+               misc |= PERF_RECORD_MISC_USER;
+       else
+               misc |= PERF_RECORD_MISC_KERNEL;
 
        return misc;
 }
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index b5b13a932561..72a201a686c5 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -190,6 +190,7 @@ config ARM64
        select HAVE_NMI
        select HAVE_PATA_PLATFORM
        select HAVE_PERF_EVENTS
+       select HAVE_GUEST_PERF_EVENTS
        select HAVE_PERF_REGS
        select HAVE_PERF_USER_STACK_DUMP
        select HAVE_REGS_AND_STACK_ACCESS_API
diff --git a/arch/csky/kernel/perf_callchain.c 
b/arch/csky/kernel/perf_callchain.c
index 35318a635a5f..92057de08f4f 100644
--- a/arch/csky/kernel/perf_callchain.c
+++ b/arch/csky/kernel/perf_callchain.c
@@ -86,13 +86,8 @@ static unsigned long user_backtrace(struct 
perf_callchain_entry_ctx *entry,
 void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
                         struct pt_regs *regs)
 {
-       struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
        unsigned long fp = 0;
 
-       /* C-SKY does not support virtualization. */
-       if (guest_cbs && guest_cbs->is_in_guest())
-               return;
-
        fp = regs->regs[4];
        perf_callchain_store(entry, regs->pc);
 
@@ -111,15 +106,8 @@ void perf_callchain_user(struct perf_callchain_entry_ctx 
*entry,
 void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
                           struct pt_regs *regs)
 {
-       struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
        struct stackframe fr;
 
-       /* C-SKY does not support virtualization. */
-       if (guest_cbs && guest_cbs->is_in_guest()) {
-               pr_warn("C-SKY does not support perf in guest mode!");
-               return;
-       }
-
        fr.fp = regs->regs[4];
        fr.lr = regs->lr;
        walk_stackframe(&fr, entry);
diff --git a/arch/nds32/kernel/perf_event_cpu.c 
b/arch/nds32/kernel/perf_event_cpu.c
index f38791960781..a78a879e7ef1 100644
--- a/arch/nds32/kernel/perf_event_cpu.c
+++ b/arch/nds32/kernel/perf_event_cpu.c
@@ -1363,7 +1363,6 @@ void
 perf_callchain_user(struct perf_callchain_entry_ctx *entry,
                    struct pt_regs *regs)
 {
-       struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
        unsigned long fp = 0;
        unsigned long gp = 0;
        unsigned long lp = 0;
@@ -1372,11 +1371,6 @@ perf_callchain_user(struct perf_callchain_entry_ctx 
*entry,
 
        leaf_fp = 0;
 
-       if (guest_cbs && guest_cbs->is_in_guest()) {
-               /* We don't support guest os callchain now */
-               return;
-       }
-
        perf_callchain_store(entry, regs->ipc);
        fp = regs->fp;
        gp = regs->gp;
@@ -1480,13 +1474,8 @@ void
 perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
                      struct pt_regs *regs)
 {
-       struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
        struct stackframe fr;
 
-       if (guest_cbs && guest_cbs->is_in_guest()) {
-               /* We don't support guest os callchain now */
-               return;
-       }
        fr.fp = regs->fp;
        fr.lp = regs->lp;
        fr.sp = regs->sp;
@@ -1495,32 +1484,17 @@ perf_callchain_kernel(struct perf_callchain_entry_ctx 
*entry,
 
 unsigned long perf_instruction_pointer(struct pt_regs *regs)
 {
-       struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
-
-       /* However, NDS32 does not support virtualization */
-       if (guest_cbs && guest_cbs->is_in_guest())
-               return guest_cbs->get_guest_ip();
-
        return instruction_pointer(regs);
 }
 
 unsigned long perf_misc_flags(struct pt_regs *regs)
 {
-       struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
        int misc = 0;
 
-       /* However, NDS32 does not support virtualization */
-       if (guest_cbs && guest_cbs->is_in_guest()) {
-               if (guest_cbs->is_user_mode())
-                       misc |= PERF_RECORD_MISC_GUEST_USER;
-               else
-                       misc |= PERF_RECORD_MISC_GUEST_KERNEL;
-       } else {
-               if (user_mode(regs))
-                       misc |= PERF_RECORD_MISC_USER;
-               else
-                       misc |= PERF_RECORD_MISC_KERNEL;
-       }
+       if (user_mode(regs))
+               misc |= PERF_RECORD_MISC_USER;
+       else
+               misc |= PERF_RECORD_MISC_KERNEL;
 
        return misc;
 }
diff --git a/arch/riscv/kernel/perf_callchain.c 
b/arch/riscv/kernel/perf_callchain.c
index 8ecfc4c128bc..1fc075b8f764 100644
--- a/arch/riscv/kernel/perf_callchain.c
+++ b/arch/riscv/kernel/perf_callchain.c
@@ -56,13 +56,8 @@ static unsigned long user_backtrace(struct 
perf_callchain_entry_ctx *entry,
 void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
                         struct pt_regs *regs)
 {
-       struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
        unsigned long fp = 0;
 
-       /* RISC-V does not support perf in guest mode. */
-       if (guest_cbs && guest_cbs->is_in_guest())
-               return;
-
        fp = regs->s0;
        perf_callchain_store(entry, regs->epc);
 
@@ -79,13 +74,5 @@ static bool fill_callchain(void *entry, unsigned long pc)
 void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
                           struct pt_regs *regs)
 {
-       struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
-
-       /* RISC-V does not support perf in guest mode. */
-       if (guest_cbs && guest_cbs->is_in_guest()) {
-               pr_warn("RISC-V does not support perf in guest mode!");
-               return;
-       }
-
        walk_stackframe(NULL, regs, fill_callchain, entry);
 }
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 49270655e827..a4de4aa7a3df 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -229,6 +229,7 @@ config X86
        select HAVE_PERF_EVENTS
        select HAVE_PERF_EVENTS_NMI
        select HAVE_HARDLOCKUP_DETECTOR_PERF    if PERF_EVENTS && 
HAVE_PERF_EVENTS_NMI
+       select HAVE_GUEST_PERF_EVENTS
        select HAVE_PCI
        select HAVE_PERF_REGS
        select HAVE_PERF_USER_STACK_DUMP
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 2b77e2154b61..e75971f85cc8 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1236,6 +1236,7 @@ extern void perf_event_bpf_event(struct bpf_prog *prog,
                                 enum perf_bpf_event_type type,
                                 u16 flags);
 
+#ifdef CONFIG_HAVE_GUEST_PERF_EVENTS
 extern struct perf_guest_info_callbacks *perf_guest_cbs;
 static inline struct perf_guest_info_callbacks *perf_get_guest_cbs(void)
 {
@@ -1247,6 +1248,7 @@ static inline struct perf_guest_info_callbacks 
*perf_get_guest_cbs(void)
 }
 extern void perf_register_guest_info_callbacks(struct 
perf_guest_info_callbacks *callbacks);
 extern void perf_unregister_guest_info_callbacks(void);
+#endif /* CONFIG_HAVE_GUEST_PERF_EVENTS */
 
 extern void perf_event_exec(void);
 extern void perf_event_comm(struct task_struct *tsk, bool exec);
@@ -1489,9 +1491,11 @@ perf_sw_event(u32 event_id, u64 nr, struct pt_regs 
*regs, u64 addr)      { }
 static inline void
 perf_bp_event(struct perf_event *event, void *data)                    { }
 
+#ifdef CONFIG_HAVE_GUEST_PERF_EVENTS
 static inline void perf_register_guest_info_callbacks
 (struct perf_guest_info_callbacks *callbacks)                          { }
 static inline void perf_unregister_guest_info_callbacks(void)          { }
+#endif
 
 static inline void perf_event_mmap(struct vm_area_struct *vma)         { }
 
diff --git a/init/Kconfig b/init/Kconfig
index 55f9f7738ebb..9ef51ae53977 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1776,6 +1776,9 @@ config HAVE_PERF_EVENTS
        help
          See tools/perf/design.txt for details.
 
+config HAVE_GUEST_PERF_EVENTS
+       bool
+
 config PERF_USE_VMALLOC
        bool
        help
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 1be95d9ace46..d7f606e06446 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -6482,6 +6482,7 @@ static void perf_pending_event(struct irq_work *entry)
                perf_swevent_put_recursion_context(rctx);
 }
 
+#ifdef CONFIG_HAVE_GUEST_PERF_EVENTS
 struct perf_guest_info_callbacks *perf_guest_cbs;
 void perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
 {
@@ -6499,6 +6500,7 @@ void perf_unregister_guest_info_callbacks(void)
        synchronize_rcu();
 }
 EXPORT_SYMBOL_GPL(perf_unregister_guest_info_callbacks);
+#endif
 
 static void
 perf_output_sample_regs(struct perf_output_handle *handle,
-- 
2.33.0.259.gc128427fd7-goog




 


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