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ANDROID: Revert "perf/core: Use static_call to optimize perf_guest_info_callbacks"

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This reverts commit 87b940a067. When
booting with the Pixel 6, I hit the below CFI failure. An email ([1])
was sent upstream to address this issue.

  Kernel panic - not syncing: CFI failure (target: __static_call_return0+0x0/0x8)
  CPU: 0 PID: 1625 Comm: batterystats-wo Tainted: G        W  OE     5.16.0-mainline #1$
  Hardware name: Raven EVT 1.1 (DT)$
  Call trace:$
   dump_backtrace+0xf0/0x130$
   show_stack+0x1c/0x2c$
   dump_stack_lvl+0x68/0x98$
   panic+0x168/0x420$
   __cfi_check_fail+0x58/0x5c$
   __cfi_slowpath_diag+0x150/0x1a4$
   perf_misc_flags+0x74/0xa4$
   perf_prepare_sample+0x50/0x44c$
   perf_event_output_forward+0x5c/0xcc$
   __perf_event_overflow+0xc8/0x188$
   perf_swevent_event+0x7c/0x10c$
   perf_tp_event+0x168/0x298$
   perf_trace_run_bpf_submit+0x8c/0xdc$
   perf_trace_sched_switch+0x180/0x1cc$
   __schedule+0x850/0x924$
   schedule+0x98/0xe0$
   binder_wait_for_work+0x158/0x368$
   binder_thread_read+0x278/0x243c$
   binder_ioctl_write_read+0x120/0x45c$
   binder_ioctl+0x1ac/0xc34$
   __arm64_sys_ioctl+0xa8/0x118$
   invoke_syscall+0x64/0x178$
   el0_svc_common+0x8c/0x100$
   do_el0_svc+0x28/0xa0$
   el0_svc+0x24/0x84$
   el0t_64_sync_handler+0x88/0xec$
   el0t_64_sync+0x1b4/0x1b8$

[1] https://lore.kernel.org/all/YfrQzoIWyv9lNljh@google.com/

Bug: 217583980
Signed-off-by: Will McVicker <willmcvicker@google.com>
Change-Id: I2951676ca4cce5e55461a71a670b35f9af41ba4e
This commit is contained in:
Will McVicker
2022-02-02 12:22:56 -08:00
parent 54df59a346
commit a82e2e9f9a
2 changed files with 26 additions and 23 deletions
Download Patch File Download Diff File Expand all files Collapse all files

34
include/linux/perf_event.h
View File

@@ -1255,22 +1255,40 @@ extern void perf_event_bpf_event(struct bpf_prog *prog,
#ifdef CONFIG_GUEST_PERF_EVENTS
extern struct perf_guest_info_callbacks __rcu *perf_guest_cbs;
DECLARE_STATIC_CALL(__perf_guest_state, *perf_guest_cbs->state);
DECLARE_STATIC_CALL(__perf_guest_get_ip, *perf_guest_cbs->get_ip);
DECLARE_STATIC_CALL(__perf_guest_handle_intel_pt_intr, *perf_guest_cbs->handle_intel_pt_intr);
static inline struct perf_guest_info_callbacks *perf_get_guest_cbs(void)
{
/*
* Callbacks are RCU-protected and must be READ_ONCE to avoid reloading
* the callbacks between a !NULL check and dereferences, to ensure
* pending stores/changes to the callback pointers are visible before a
* non-NULL perf_guest_cbs is visible to readers, and to prevent a
* module from unloading callbacks while readers are active.
*/
return rcu_dereference(perf_guest_cbs);
}
static inline unsigned int perf_guest_state(void)
{
return static_call(__perf_guest_state)();
struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
return guest_cbs ? guest_cbs->state() : 0;
}
static inline unsigned long perf_guest_get_ip(void)
{
return static_call(__perf_guest_get_ip)();
struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
/*
* Arbitrarily return '0' in the unlikely scenario that the callbacks
* are unregistered between checking guest state and getting the IP.
*/
return guest_cbs ? guest_cbs->get_ip() : 0;
}
static inline unsigned int perf_guest_handle_intel_pt_intr(void)
{
return static_call(__perf_guest_handle_intel_pt_intr)();
struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
if (guest_cbs && guest_cbs->handle_intel_pt_intr)
return guest_cbs->handle_intel_pt_intr();
return 0;
}
extern void perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs);
extern void perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *cbs);

15
kernel/events/core.c
View File

@@ -6529,23 +6529,12 @@ static void perf_pending_event(struct irq_work *entry)
#ifdef CONFIG_GUEST_PERF_EVENTS
struct perf_guest_info_callbacks __rcu *perf_guest_cbs;
DEFINE_STATIC_CALL_RET0(__perf_guest_state, *perf_guest_cbs->state);
DEFINE_STATIC_CALL_RET0(__perf_guest_get_ip, *perf_guest_cbs->get_ip);
DEFINE_STATIC_CALL_RET0(__perf_guest_handle_intel_pt_intr, *perf_guest_cbs->handle_intel_pt_intr);
void perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
{
if (WARN_ON_ONCE(rcu_access_pointer(perf_guest_cbs)))
return;
rcu_assign_pointer(perf_guest_cbs, cbs);
static_call_update(__perf_guest_state, cbs->state);
static_call_update(__perf_guest_get_ip, cbs->get_ip);
/* Implementing ->handle_intel_pt_intr is optional. */
if (cbs->handle_intel_pt_intr)
static_call_update(__perf_guest_handle_intel_pt_intr,
cbs->handle_intel_pt_intr);
}
EXPORT_SYMBOL_GPL(perf_register_guest_info_callbacks);
@@ -6555,10 +6544,6 @@ void perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
return;
rcu_assign_pointer(perf_guest_cbs, NULL);
static_call_update(__perf_guest_state, (void *)&__static_call_return0);
static_call_update(__perf_guest_get_ip, (void *)&__static_call_return0);
static_call_update(__perf_guest_handle_intel_pt_intr,
(void *)&__static_call_return0);
synchronize_rcu();
}
EXPORT_SYMBOL_GPL(perf_unregister_guest_info_callbacks);