On x86_64, at least, task_pt_regs may be only partially initialized
in many contexts, so x86_64 should not use it without extra care
from interrupt context, let alone NMI context.
This will allow x86_64 to override the logic and will supply some
scratch space to use to make a cleaner copy of user regs.
Signed-off-by: Andy Lutomirski <l...@amacapital.net>
---
arch/arm/kernel/perf_regs.c | 8 ++++++++
arch/arm64/kernel/perf_regs.c | 8 ++++++++
arch/x86/kernel/perf_regs.c | 16 ++++++++++++++++
include/linux/perf_event.h | 12 +++++++-----
include/linux/perf_regs.h | 16 ++++++++++++++++
kernel/events/core.c | 19 ++++++++-----------
6 files changed, 63 insertions(+), 16 deletions(-)
diff --git a/arch/arm/kernel/perf_regs.c b/arch/arm/kernel/perf_regs.c
index 6e4379c67cbc..592dda3f21ff 100644
--- a/arch/arm/kernel/perf_regs.c
+++ b/arch/arm/kernel/perf_regs.c
@@ -28,3 +28,11 @@ u64 perf_reg_abi(struct task_struct *task)
{
return PERF_SAMPLE_REGS_ABI_32;
}
+
+void perf_get_regs_user(struct perf_regs *regs_user,
+ struct pt_regs *regs,
+ struct pt_regs *regs_user_copy)
+{
+ regs_user->regs = task_pt_regs(current);
+ regs_user->abi = perf_reg_abi(current);
+}
diff --git a/arch/arm64/kernel/perf_regs.c b/arch/arm64/kernel/perf_regs.c
index 6762ad705587..3f62b35fb6f1 100644
--- a/arch/arm64/kernel/perf_regs.c
+++ b/arch/arm64/kernel/perf_regs.c
@@ -50,3 +50,11 @@ u64 perf_reg_abi(struct task_struct *task)
else
return PERF_SAMPLE_REGS_ABI_64;
}
+
+void perf_get_regs_user(struct perf_regs *regs_user,
+ struct pt_regs *regs,
+ struct pt_regs *regs_user_copy)
+{
+ regs_user->regs = task_pt_regs(current);
+ regs_user->abi = perf_reg_abi(current);
+}
diff --git a/arch/x86/kernel/perf_regs.c b/arch/x86/kernel/perf_regs.c
index e309cc5c276e..3bbbb1a4fb52 100644
--- a/arch/x86/kernel/perf_regs.c
+++ b/arch/x86/kernel/perf_regs.c
@@ -78,6 +78,14 @@ u64 perf_reg_abi(struct task_struct *task)
{
return PERF_SAMPLE_REGS_ABI_32;
}
+
+void perf_get_regs_user(struct perf_regs *regs_user,
+ struct pt_regs *regs,
+ struct pt_regs *regs_user_copy)
+{
+ regs_user->regs = task_pt_regs(current);
+ regs_user->abi = perf_reg_abi(current);
+}
#else /* CONFIG_X86_64 */
#define REG_NOSUPPORT ((1ULL << PERF_REG_X86_DS) | \
(1ULL << PERF_REG_X86_ES) | \
@@ -102,4 +110,12 @@ u64 perf_reg_abi(struct task_struct *task)
else
return PERF_SAMPLE_REGS_ABI_64;
}
+
+void perf_get_regs_user(struct perf_regs *regs_user,
+ struct pt_regs *regs,
+ struct pt_regs *regs_user_copy)
+{
+ regs_user->regs = task_pt_regs(current);
+ regs_user->abi = perf_reg_abi(current);
+}
#endif /* CONFIG_X86_32 */
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 486e84ccb1f9..4f7a61ca4b39 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -79,11 +79,6 @@ struct perf_branch_stack {
struct perf_branch_entry entries[0];
};
-struct perf_regs {
- __u64 abi;
- struct pt_regs *regs;
-};
-
struct task_struct;
/*
@@ -610,7 +605,14 @@ struct perf_sample_data {
u32 reserved;
} cpu_entry;
struct perf_callchain_entry *callchain;
+
+ /*
+ * regs_user may point to task_pt_regs or to regs_user_copy, depending
+ * on arch details.
+ */
struct perf_regs regs_user;
+ struct pt_regs regs_user_copy;
+
struct perf_regs regs_intr;
u64 stack_user_size;
} ____cacheline_aligned;
diff --git a/include/linux/perf_regs.h b/include/linux/perf_regs.h
index 3c73d5fe18be..a5f98d53d732 100644
--- a/include/linux/perf_regs.h
+++ b/include/linux/perf_regs.h
@@ -1,11 +1,19 @@
#ifndef _LINUX_PERF_REGS_H
#define _LINUX_PERF_REGS_H
+struct perf_regs {
+ __u64 abi;
+ struct pt_regs *regs;
+};
+
#ifdef CONFIG_HAVE_PERF_REGS
#include <asm/perf_regs.h>
u64 perf_reg_value(struct pt_regs *regs, int idx);
int perf_reg_validate(u64 mask);
u64 perf_reg_abi(struct task_struct *task);
+void perf_get_regs_user(struct perf_regs *regs_user,
+ struct pt_regs *regs,
+ struct pt_regs *regs_user_copy);
#else
static inline u64 perf_reg_value(struct pt_regs *regs, int idx)
{
@@ -21,5 +29,13 @@ static inline u64 perf_reg_abi(struct task_struct *task)
{
return PERF_SAMPLE_REGS_ABI_NONE;
}
+
+static inline void perf_get_regs_user(struct perf_regs *regs_user,
+ struct pt_regs *regs,
+ struct pt_regs *regs_user_copy)
+{
+ regs_user->regs = task_pt_regs(current);
+ regs_user->abi = perf_reg_abi(current);
+}
#endif /* CONFIG_HAVE_PERF_REGS */
#endif /* _LINUX_PERF_REGS_H */
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 4c1ee7f2bebc..882f835a0d85 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -4461,18 +4461,14 @@ perf_output_sample_regs(struct perf_output_handle
*handle,
}
static void perf_sample_regs_user(struct perf_regs *regs_user,
- struct pt_regs *regs)
+ struct pt_regs *regs,
+ struct pt_regs *regs_user_copy)
{
- if (!user_mode(regs)) {
- if (current->mm)
- regs = task_pt_regs(current);
- else
- regs = NULL;
- }
-
- if (regs) {
- regs_user->abi = perf_reg_abi(current);
+ if (user_mode(regs)) {
+ regs_user->abi = perf_reg_abi(current);
regs_user->regs = regs;
+ } else if (current->mm) {
+ perf_get_regs_user(regs_user, regs, regs_user_copy);
} else {
regs_user->abi = PERF_SAMPLE_REGS_ABI_NONE;
regs_user->regs = NULL;
@@ -4951,7 +4947,8 @@ void perf_prepare_sample(struct perf_event_header *header,
}
if (sample_type & (PERF_SAMPLE_REGS_USER | PERF_SAMPLE_STACK_USER))
- perf_sample_regs_user(&data->regs_user, regs);
+ perf_sample_regs_user(&data->regs_user, regs,
+ &data->regs_user_copy);
if (sample_type & PERF_SAMPLE_REGS_USER) {
/* regs dump ABI info */
--
2.1.0
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