checkpoint: Add dumping of FPU state

The dumping of FPU state is done with help of ptrace
facility. There are two cases which we need to handle
depending on which features are available on host machine

1) The dump via ptrace(PTRACE_GETFPREGS ...)

   In this case the kernel will use fxsave approach
   inside the kenrel and provides us back the data
   encoded in i387_fxsave_struct format.

2) The dump via ptrace(PTRACE_GETREGSET ...)

   In this case the kernel will use xsave approach
   inside the kernel and provides us back the data
   encoded in xsave_struct format.

In any case we decode data and save it in protobuf format.
This is why core.proto file has been extended to keep new
entries.
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

cr-dump.c

@@ -61,6 +61,8 @@
 #include "net.h"
 #include "sk-packet.h"
 #include "cpu.h"
+#include "fpu.h"
+#include "elf.h"
 
 #ifndef CONFIG_X86_64
 # error No x86-32 support yet
@@ -649,9 +651,10 @@ err:
 
 static int get_task_regs(pid_t pid, CoreEntry *core, const struct parasite_ctl *ctl)
 {
-	user_fpregs_struct_t fpregs	= {-1};
+	struct xsave_struct xsave	= {  };
 	user_regs_struct_t regs		= {-1};
 
+	struct iovec iov;
 	int ret = -1;
 
 	pr_info("Dumping GP/FPU registers ... ");
@@ -665,11 +668,6 @@ static int get_task_regs(pid_t pid, CoreEntry *core, const struct parasite_ctl *
 		}
 	}
 
-	if (ptrace(PTRACE_GETFPREGS, pid, NULL, &fpregs)) {
-		pr_err("Can't obtain FPU registers for %d\n", pid);
-		goto err;
-	}
-
 	/* Did we come from a system call? */
 	if ((int)regs.orig_ax >= 0) {
 		/* Restart the system call */
@@ -718,25 +716,60 @@ static int get_task_regs(pid_t pid, CoreEntry *core, const struct parasite_ctl *
 	assign_reg(core->thread_info->gpregs, regs, fs);
 	assign_reg(core->thread_info->gpregs, regs, gs);
 
-	assign_reg(core->thread_info->fpregs, fpregs, cwd);
-	assign_reg(core->thread_info->fpregs, fpregs, swd);
-	assign_reg(core->thread_info->fpregs, fpregs, twd);
-	assign_reg(core->thread_info->fpregs, fpregs, fop);
-	assign_reg(core->thread_info->fpregs, fpregs, rip);
-	assign_reg(core->thread_info->fpregs, fpregs, rdp);
-	assign_reg(core->thread_info->fpregs, fpregs, mxcsr);
-	assign_reg(core->thread_info->fpregs, fpregs, mxcsr_mask);
+#ifndef PTRACE_GETREGSET
+# define PTRACE_GETREGSET 0x4204
+#endif
+
+	if (!cpu_has_feature(X86_FEATURE_FPU))
+		goto out;
+
+	/*
+	 * FPU fetched either via fxsave or via xsave,
+	 * thus decode it accrodingly.
+	 */
+
+	if (cpu_has_feature(X86_FEATURE_XSAVE)) {
+		iov.iov_base = &xsave;
+		iov.iov_len = sizeof(xsave);
+
+		if (ptrace(PTRACE_GETREGSET, pid, (unsigned int)NT_X86_XSTATE, &iov) < 0) {
+			pr_err("Can't obtain FPU registers for %d\n", pid);
+			goto err;
+		}
+	} else {
+		if (ptrace(PTRACE_GETFPREGS, pid, NULL, &xsave)) {
+			pr_err("Can't obtain FPU registers for %d\n", pid);
+			goto err;
+		}
+	}
+
+	assign_reg(core->thread_info->fpregs, xsave.i387, cwd);
+	assign_reg(core->thread_info->fpregs, xsave.i387, swd);
+	assign_reg(core->thread_info->fpregs, xsave.i387, twd);
+	assign_reg(core->thread_info->fpregs, xsave.i387, fop);
+	assign_reg(core->thread_info->fpregs, xsave.i387, rip);
+	assign_reg(core->thread_info->fpregs, xsave.i387, rdp);
+	assign_reg(core->thread_info->fpregs, xsave.i387, mxcsr);
+	assign_reg(core->thread_info->fpregs, xsave.i387, mxcsr_mask);
 
 	/* Make sure we have enough space */
-	BUG_ON(core->thread_info->fpregs->n_st_space != ARRAY_SIZE(fpregs.st_space));
-	BUG_ON(core->thread_info->fpregs->n_xmm_space != ARRAY_SIZE(fpregs.xmm_space));
+	BUG_ON(core->thread_info->fpregs->n_st_space != ARRAY_SIZE(xsave.i387.st_space));
+	BUG_ON(core->thread_info->fpregs->n_xmm_space != ARRAY_SIZE(xsave.i387.xmm_space));
+
+	assign_array(core->thread_info->fpregs, xsave.i387, st_space);
+	assign_array(core->thread_info->fpregs, xsave.i387, xmm_space);
 
-	assign_array(core->thread_info->fpregs, fpregs,	st_space);
-	assign_array(core->thread_info->fpregs, fpregs,	xmm_space);
+	if (cpu_has_feature(X86_FEATURE_XSAVE)) {
+		BUG_ON(core->thread_info->fpregs->xsave->n_ymmh_space != ARRAY_SIZE(xsave.ymmh.ymmh_space));
+
+		assign_reg(core->thread_info->fpregs->xsave, xsave.xsave_hdr, xstate_bv);
+		assign_array(core->thread_info->fpregs->xsave, xsave.ymmh, ymmh_space);
+	}
 
 #undef assign_reg
 #undef assign_array
 
+out:
 	ret = 0;
 
 err:
@@ -793,6 +826,9 @@ static void core_entry_free(CoreEntry *core)
 	if (core) {
 		if (core->thread_info) {
 			if (core->thread_info->fpregs) {
+				if (core->thread_info->fpregs->xsave)
+					xfree(core->thread_info->fpregs->xsave->ymmh_space);
+				xfree(core->thread_info->fpregs->xsave);
 				xfree(core->thread_info->fpregs->st_space);
 				xfree(core->thread_info->fpregs->xmm_space);
 				xfree(core->thread_info->fpregs->padding);
@@ -845,22 +881,37 @@ static CoreEntry *core_entry_alloc(int alloc_thread_info,
 		user_x86_regs_entry__init(gpregs);
 		thread_info->gpregs = gpregs;
 
-		fpregs = xmalloc(sizeof(*fpregs));
-		if (!fpregs)
-			goto err;
-		user_x86_fpregs_entry__init(fpregs);
-		thread_info->fpregs = fpregs;
+		if (cpu_has_feature(X86_FEATURE_FPU)) {
+			fpregs = xmalloc(sizeof(*fpregs));
+			if (!fpregs)
+				goto err;
+			user_x86_fpregs_entry__init(fpregs);
+			thread_info->fpregs = fpregs;
 
-		/* These are numbers from kernel */
-		fpregs->n_st_space	= 32;
-		fpregs->n_xmm_space	= 64;
+			/* These are numbers from kernel */
+			fpregs->n_st_space	= 32;
+			fpregs->n_xmm_space	= 64;
 
-		fpregs->st_space	= xzalloc(pb_repeated_size(fpregs, st_space));
-		fpregs->xmm_space	= xzalloc(pb_repeated_size(fpregs, xmm_space));
+			fpregs->st_space	= xzalloc(pb_repeated_size(fpregs, st_space));
+			fpregs->xmm_space	= xzalloc(pb_repeated_size(fpregs, xmm_space));
 
-		if (!fpregs->st_space || !fpregs->xmm_space)
-			goto err;
+			if (!fpregs->st_space || !fpregs->xmm_space)
+				goto err;
 
+			if (cpu_has_feature(X86_FEATURE_XSAVE)) {
+				UserX86XsaveEntry *xsave;
+				xsave = xmalloc(sizeof(*xsave));
+				if (!xsave)
+					goto err;
+				user_x86_xsave_entry__init(xsave);
+				thread_info->fpregs->xsave = xsave;
+
+				xsave->n_ymmh_space = 64;
+				xsave->ymmh_space = xzalloc(pb_repeated_size(xsave, ymmh_space));
+				if (!xsave->ymmh_space)
+					goto err;
+			}
+		}
 	}
 
 	if (alloc_tc) {

protobuf/core.proto

@@ -28,7 +28,14 @@ message user_x86_regs_entry {
 	required uint64			gs		= 27;
 }
 
+message user_x86_xsave_entry {
+	required uint64			xstate_bv	=  1;
+	repeated uint32			ymmh_space	=  2;
+}
+
 message user_x86_fpregs_entry {
+
+	/* fxsave data */
 	required uint32			cwd		=  1;
 	required uint32			swd		=  2;
 	required uint32			twd		=  3;
@@ -42,6 +49,9 @@ message user_x86_fpregs_entry {
 
 	/* Unused, but present for backward compatibility */
 	repeated uint32			padding		= 11;
+
+	/* xsave extension */
+	optional user_x86_xsave_entry	xsave		= 13;
 }
 
 message task_core_entry {