s390/gs: add regset for the guarded storage broadcast control block

The guarded storage interface allows to register a control block for
each thread that is activated with the guarded storage broadcast event.
To retrieve the complete state of a process from the kernel a register
set for the stored broadcast control block is required.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

2 files changed, 47 insertions, 0 deletions

diff --git a/arch/s390/kernel/ptrace.c b/arch/s390/kernel/ptrace.c
index c933e255b5d5..488c5bb8dc77 100644
--- a/arch/s390/kernel/ptrace.c
+++ b/arch/s390/kernel/ptrace.c
@@ -1173,8 +1173,46 @@ static int s390_gs_cb_set(struct task_struct *target,
 
         if (!MACHINE_HAS_GS)
                 return -ENODEV;
+        if (!data) {
+                data = kzalloc(sizeof(*data), GFP_KERNEL);
+                if (!data)
+                        return -ENOMEM;
+                target->thread.gs_cb = data;
+        }
+        return user_regset_copyin(&pos, &count, &kbuf, &ubuf,
+                                  data, 0, sizeof(struct gs_cb));
+}
+
+static int s390_gs_bc_get(struct task_struct *target,
+                          const struct user_regset *regset,
+                          unsigned int pos, unsigned int count,
+                          void *kbuf, void __user *ubuf)
+{
+        struct gs_cb *data = target->thread.gs_bc_cb;
+
+        if (!MACHINE_HAS_GS)
+                return -ENODEV;
         if (!data)
                 return -ENODATA;
+        return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
+                                   data, 0, sizeof(struct gs_cb));
+}
+
+static int s390_gs_bc_set(struct task_struct *target,
+                          const struct user_regset *regset,
+                          unsigned int pos, unsigned int count,
+                          const void *kbuf, const void __user *ubuf)
+{
+        struct gs_cb *data = target->thread.gs_bc_cb;
+
+        if (!MACHINE_HAS_GS)
+                return -ENODEV;
+        if (!data) {
+                data = kzalloc(sizeof(*data), GFP_KERNEL);
+                if (!data)
+                        return -ENOMEM;
+                target->thread.gs_bc_cb = data;
+        }
         return user_regset_copyin(&pos, &count, &kbuf, &ubuf,
                                   data, 0, sizeof(struct gs_cb));
 }
@@ -1244,6 +1282,14 @@ static const struct user_regset s390_regsets[] = {
                 .get = s390_gs_cb_get,
                 .set = s390_gs_cb_set,
         },
+        {
+                .core_note_type = NT_S390_GS_BC,
+                .n = sizeof(struct gs_cb) / sizeof(__u64),
+                .size = sizeof(__u64),
+                .align = sizeof(__u64),
+                .get = s390_gs_bc_get,
+                .set = s390_gs_bc_set,
+        },
 };
 
 static const struct user_regset_view user_s390_view = {
diff --git a/include/uapi/linux/elf.h b/include/uapi/linux/elf.h
index 8c6d3bdb9a00..176b6cb1008d 100644
--- a/include/uapi/linux/elf.h
+++ b/include/uapi/linux/elf.h
@@ -410,6 +410,7 @@ typedef struct elf64_shdr {
 #define NT_S390_VXRS_LOW        0x309   /* s390 vector registers 0-15 upper half */
 #define NT_S390_VXRS_HIGH       0x30a   /* s390 vector registers 16-31 */
 #define NT_S390_GS_CB   0x30b           /* s390 guarded storage registers */
+#define NT_S390_GS_BC   0x30c           /* s390 guarded storage broadcast control block */
 #define NT_ARM_VFP      0x400           /* ARM VFP/NEON registers */
 #define NT_ARM_TLS      0x401           /* ARM TLS register */
 #define NT_ARM_HW_BREAK 0x402           /* ARM hardware breakpoint registers */