[PATCH v3 05/16] perf: Drop dead and useless guest "support" from arm, csky, nds32 and riscv

Sean Christopherson
2021-09-22T00:06:07Z

Drop "support" for guest callbacks from architctures that don't implement
the guest callbacks. 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.

A future patch will also add a Kconfig to force architcture to opt into
the callbacks to make it more difficult for uses "support" to sneak in in
the future.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/arm/kernel/perf_callchain.c | 33 ++++-------------------------
arch/csky/kernel/perf_callchain.c | 12 -----------
arch/nds32/kernel/perf_event_cpu.c | 34 ++++--------------------------
arch/riscv/kernel/perf_callchain.c | 13 ------------
4 files changed, 8 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/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);
}
--
2.33.0.464.g1972c5931b-goog