Re: [uml-devel] [PATCH] um: v3: Fix FP register size for XSTATE/XSAVE

Wed, 12 Jul 2017 12:53:47 -0700 

Thomas,

what about something like that? (untested)
Still not very pretty but IMHO better.

diff --git a/arch/um/include/asm/thread_info.h 
b/arch/um/include/asm/thread_info.h
index 053baff03674..9300f7630d2a 100644
--- a/arch/um/include/asm/thread_info.h
+++ b/arch/um/include/asm/thread_info.h
@@ -11,6 +11,7 @@
 #include <asm/types.h>
 #include <asm/page.h>
 #include <asm/segment.h>
+#include <sysdep/ptrace_user.h>

 struct thread_info {
        struct task_struct      *task;          /* main task structure */
@@ -22,6 +23,8 @@ struct thread_info {
                                                   0-0xBFFFFFFF for user
                                                   0-0xFFFFFFFF for kernel */
        struct thread_info      *real_thread;    /* Points to non-IRQ stack */
+       unsigned long aux_fp_regs[FP_SIZE];     /* auxiliary fp_regs to 
save/restore
+                                                  them out-of-band */
 };

 #define INIT_THREAD_INFO(tsk)                  \
diff --git a/arch/um/include/shared/os.h b/arch/um/include/shared/os.h
index cd1fa97776c3..c1d4b6fbc919 100644
--- a/arch/um/include/shared/os.h
+++ b/arch/um/include/shared/os.h
@@ -274,7 +274,7 @@ extern int protect(struct mm_id * mm_idp, unsigned long 
addr,
 extern int is_skas_winch(int pid, int fd, void *data);
 extern int start_userspace(unsigned long stub_stack);
 extern int copy_context_skas0(unsigned long stack, int pid);
-extern void userspace(struct uml_pt_regs *regs);
+extern void userspace(struct uml_pt_regs *regs, unsigned long *aux_fp_regs);
 extern int map_stub_pages(int fd, unsigned long code, unsigned long data,
                          unsigned long stack);
 extern void new_thread(void *stack, jmp_buf *buf, void (*handler)(void));
diff --git a/arch/um/kernel/process.c b/arch/um/kernel/process.c
index 2c7f721eccbc..691b83b10649 100644
--- a/arch/um/kernel/process.c
+++ b/arch/um/kernel/process.c
@@ -131,7 +131,7 @@ void new_thread_handler(void)
         * callback returns only if the kernel thread execs a process
         */
        n = fn(arg);
-       userspace(&current->thread.regs.regs);
+       userspace(&current->thread.regs.regs, 
current_thread_info()->aux_fp_regs);
 }

 /* Called magically, see new_thread_handler above */
@@ -150,7 +150,7 @@ void fork_handler(void)

        current->thread.prev_sched = NULL;

-       userspace(&current->thread.regs.regs);
+       userspace(&current->thread.regs.regs, 
current_thread_info()->aux_fp_regs);
 }

 int copy_thread(unsigned long clone_flags, unsigned long sp,
diff --git a/arch/um/os-Linux/skas/process.c b/arch/um/os-Linux/skas/process.c
index 03b3c4cc7735..d92a0240dce4 100644
--- a/arch/um/os-Linux/skas/process.c
+++ b/arch/um/os-Linux/skas/process.c
@@ -88,12 +88,11 @@ void wait_stub_done(int pid)

 extern unsigned long current_stub_stack(void);

-static void get_skas_faultinfo(int pid, struct faultinfo *fi)
+static void get_skas_faultinfo(int pid, struct faultinfo *fi, unsigned long 
*aux_fp_regs)
 {
        int err;
-       unsigned long fpregs[FP_SIZE];

-       err = get_fp_registers(pid, fpregs);
+       err = get_fp_registers(pid, aux_fp_regs);
        if (err < 0) {
                printk(UM_KERN_ERR "save_fp_registers returned %d\n",
                       err);
@@ -113,7 +112,7 @@ static void get_skas_faultinfo(int pid, struct faultinfo 
*fi)
         */
        memcpy(fi, (void *)current_stub_stack(), sizeof(*fi));

-       err = put_fp_registers(pid, fpregs);
+       err = put_fp_registers(pid, aux_fp_regs);
        if (err < 0) {
                printk(UM_KERN_ERR "put_fp_registers returned %d\n",
                       err);
@@ -121,9 +120,9 @@ static void get_skas_faultinfo(int pid, struct faultinfo 
*fi)
        }
 }

-static void handle_segv(int pid, struct uml_pt_regs * regs)
+static void handle_segv(int pid, struct uml_pt_regs *regs, unsigned long 
*aux_fp_regs)
 {
-       get_skas_faultinfo(pid, &regs->faultinfo);
+       get_skas_faultinfo(pid, &regs->faultinfo, aux_fp_regs);
        segv(regs->faultinfo, 0, 1, NULL);
 }

@@ -303,7 +302,7 @@ int start_userspace(unsigned long stub_stack)
        return err;
 }

-void userspace(struct uml_pt_regs *regs)
+void userspace(struct uml_pt_regs *regs, unsigned long *aux_fp_regs)
 {
        int err, status, op, pid = userspace_pid[0];
        /* To prevent races if using_sysemu changes under us.*/
@@ -372,11 +371,11 @@ void userspace(struct uml_pt_regs *regs)
                        case SIGSEGV:
                                if (PTRACE_FULL_FAULTINFO) {
                                        get_skas_faultinfo(pid,
-                                                          &regs->faultinfo);
+                                                          &regs->faultinfo, 
aux_fp_regs);
                                        (*sig_info[SIGSEGV])(SIGSEGV, (struct 
siginfo *)&si,
                                                             regs);
                                }
-                               else handle_segv(pid, regs);
+                               else handle_segv(pid, regs, aux_fp_regs);
                                break;
                        case SIGTRAP + 0x80:
                                handle_trap(pid, regs, local_using_sysemu);

Thanks,
//richard

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