4 files changed, 119 insertions, 3 deletions

diff --git a/arch/x86/kernel/perf_regs.c b/arch/x86/kernel/perf_regs.c
index 3d6923528b1c..c5a3e5cfe07f 100644
--- a/arch/x86/kernel/perf_regs.c
+++ b/arch/x86/kernel/perf_regs.c
@@ -1,5 +1,7 @@
 #include <linux/errno.h>
 #include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/perf_event.h>
 #include <linux/bug.h>
 #include <linux/stddef.h>
 #include <asm/perf_regs.h>
@@ -71,6 +73,11 @@ int perf_reg_validate(u64 mask)
 
         return 0;
 }
+
+u64 perf_reg_abi(struct task_struct *task)
+{
+        return PERF_SAMPLE_REGS_ABI_32;
+}
 #else /* CONFIG_X86_64 */
 #define REG_NOSUPPORT ((1ULL << PERF_REG_X86_DS) | \
                        (1ULL << PERF_REG_X86_ES) | \
@@ -87,4 +94,12 @@ int perf_reg_validate(u64 mask)
 
         return 0;
 }
+
+u64 perf_reg_abi(struct task_struct *task)
+{
+        if (test_tsk_thread_flag(task, TIF_IA32))
+                return PERF_SAMPLE_REGS_ABI_32;
+        else
+                return PERF_SAMPLE_REGS_ABI_64;
+}
 #endif /* CONFIG_X86_32 */
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 7602ccb3f40e..3d4d84745f07 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -130,8 +130,9 @@ enum perf_event_sample_format {
         PERF_SAMPLE_STREAM_ID                   = 1U << 9,
         PERF_SAMPLE_RAW                         = 1U << 10,
         PERF_SAMPLE_BRANCH_STACK                = 1U << 11,
+        PERF_SAMPLE_REGS_USER                   = 1U << 12,
 
-        PERF_SAMPLE_MAX = 1U << 12,             /* non-ABI */
+        PERF_SAMPLE_MAX = 1U << 13,             /* non-ABI */
 };
 
 /*
@@ -163,6 +164,15 @@ enum perf_branch_sample_type {
          PERF_SAMPLE_BRANCH_HV)
 
 /*
+ * Values to determine ABI of the registers dump.
+ */
+enum perf_sample_regs_abi {
+        PERF_SAMPLE_REGS_ABI_NONE       = 0,
+        PERF_SAMPLE_REGS_ABI_32         = 1,
+        PERF_SAMPLE_REGS_ABI_64         = 2,
+};
+
+/*
  * The format of the data returned by read() on a perf event fd,
  * as specified by attr.read_format:
  *
@@ -194,6 +204,7 @@ enum perf_event_read_format {
 #define PERF_ATTR_SIZE_VER0     64      /* sizeof first published struct */
 #define PERF_ATTR_SIZE_VER1     72      /* add: config2 */
 #define PERF_ATTR_SIZE_VER2     80      /* add: branch_sample_type */
+#define PERF_ATTR_SIZE_VER3     88      /* add: sample_regs_user */
 
 /*
  * Hardware event_id to monitor via a performance monitoring event:
@@ -271,7 +282,13 @@ struct perf_event_attr {
                 __u64           bp_len;
                 __u64           config2; /* extension of config1 */
         };
-        __u64   branch_sample_type; /* enum branch_sample_type */
+        __u64   branch_sample_type; /* enum perf_branch_sample_type */
+
+        /*
+         * Defines set of user regs to dump on samples.
+         * See asm/perf_regs.h for details.
+         */
+        __u64   sample_regs_user;
 };
 
 /*
@@ -548,6 +565,9 @@ enum perf_event_type {
          *        char                  data[size];}&& PERF_SAMPLE_RAW
          *
          *      { u64 from, to, flags } lbr[nr];} && PERF_SAMPLE_BRANCH_STACK
+         *
+         *      { u64                   abi; # enum perf_sample_regs_abi
+         *        u64                   regs[weight(mask)]; } && PERF_SAMPLE_REGS_USER
          * };
          */
         PERF_RECORD_SAMPLE                      = 9,
@@ -609,6 +629,7 @@ struct perf_guest_info_callbacks {
 #include <linux/static_key.h>
 #include <linux/atomic.h>
 #include <linux/sysfs.h>
+#include <linux/perf_regs.h>
 #include <asm/local.h>
 
 struct perf_callchain_entry {
@@ -654,6 +675,11 @@ struct perf_branch_stack {
         struct perf_branch_entry        entries[0];
 };
 
+struct perf_regs_user {
+        __u64           abi;
+        struct pt_regs  *regs;
+};
+
 struct task_struct;
 
 /*
@@ -1133,6 +1159,7 @@ struct perf_sample_data {
         struct perf_callchain_entry     *callchain;
         struct perf_raw_record          *raw;
         struct perf_branch_stack        *br_stack;
+        struct perf_regs_user           regs_user;
 };
 
 static inline void perf_sample_data_init(struct perf_sample_data *data,
@@ -1142,7 +1169,9 @@ static inline void perf_sample_data_init(struct perf_sample_data *data,
         data->addr = addr;
         data->raw  = NULL;
         data->br_stack = NULL;
-        data->period    = period;
+        data->period = period;
+        data->regs_user.abi = PERF_SAMPLE_REGS_ABI_NONE;
+        data->regs_user.regs = NULL;
 }
 
 extern void perf_output_sample(struct perf_output_handle *handle,
diff --git a/include/linux/perf_regs.h b/include/linux/perf_regs.h
index a2f1a98f7839..3c73d5fe18be 100644
--- a/include/linux/perf_regs.h
+++ b/include/linux/perf_regs.h
@@ -5,6 +5,7 @@
 #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);
 #else
 static inline u64 perf_reg_value(struct pt_regs *regs, int idx)
 {
@@ -15,5 +16,10 @@ static inline int perf_reg_validate(u64 mask)
 {
         return mask ? -ENOSYS : 0;
 }
+
+static inline u64 perf_reg_abi(struct task_struct *task)
+{
+        return PERF_SAMPLE_REGS_ABI_NONE;
+}
 #endif /* CONFIG_HAVE_PERF_REGS */
 #endif /* _LINUX_PERF_REGS_H */
diff --git a/kernel/events/core.c b/kernel/events/core.c
index b7935fcec7d9..d3ce97525b9f 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -3756,6 +3756,37 @@ int perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
 }
 EXPORT_SYMBOL_GPL(perf_unregister_guest_info_callbacks);
 
+static void
+perf_output_sample_regs(struct perf_output_handle *handle,
+                        struct pt_regs *regs, u64 mask)
+{
+        int bit;
+
+        for_each_set_bit(bit, (const unsigned long *) &mask,
+                         sizeof(mask) * BITS_PER_BYTE) {
+                u64 val;
+
+                val = perf_reg_value(regs, bit);
+                perf_output_put(handle, val);
+        }
+}
+
+static void perf_sample_regs_user(struct perf_regs_user *regs_user,
+                                  struct pt_regs *regs)
+{
+        if (!user_mode(regs)) {
+                if (current->mm)
+                        regs = task_pt_regs(current);
+                else
+                        regs = NULL;
+        }
+
+        if (regs) {
+                regs_user->regs = regs;
+                regs_user->abi  = perf_reg_abi(current);
+        }
+}
+
 static void __perf_event_header__init_id(struct perf_event_header *header,
                                          struct perf_sample_data *data,
                                          struct perf_event *event)
@@ -4016,6 +4047,23 @@ void perf_output_sample(struct perf_output_handle *handle,
                         perf_output_put(handle, nr);
                 }
         }
+
+        if (sample_type & PERF_SAMPLE_REGS_USER) {
+                u64 abi = data->regs_user.abi;
+
+                /*
+                 * If there are no regs to dump, notice it through
+                 * first u64 being zero (PERF_SAMPLE_REGS_ABI_NONE).
+                 */
+                perf_output_put(handle, abi);
+
+                if (abi) {
+                        u64 mask = event->attr.sample_regs_user;
+                        perf_output_sample_regs(handle,
+                                                data->regs_user.regs,
+                                                mask);
+                }
+        }
 }
 
 void perf_prepare_sample(struct perf_event_header *header,
@@ -4067,6 +4115,20 @@ void perf_prepare_sample(struct perf_event_header *header,
                 }
                 header->size += size;
         }
+
+        if (sample_type & PERF_SAMPLE_REGS_USER) {
+                /* regs dump ABI info */
+                int size = sizeof(u64);
+
+                perf_sample_regs_user(&data->regs_user, regs);
+
+                if (data->regs_user.regs) {
+                        u64 mask = event->attr.sample_regs_user;
+                        size += hweight64(mask) * sizeof(u64);
+                }
+
+                header->size += size;
+        }
 }
 
 static void perf_event_output(struct perf_event *event,
@@ -6142,6 +6204,10 @@ static int perf_copy_attr(struct perf_event_attr __user *uattr,
                         attr->branch_sample_type = mask;
                 }
         }
+
+        if (attr->sample_type & PERF_SAMPLE_REGS_USER)
+                ret = perf_reg_validate(attr->sample_regs_user);
+
 out:
         return ret;