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

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

[Thomas Meyer]

Hard code max size. Taken from
https://sourceware.org/git/?p=binutils-gdb.git;a=blob;f=gdb/common/x86-xstate.h

Signed-off-by: Thomas Meyer <thomas@m3y3r.de>
---
 arch/x86/um/os-Linux/registers.c | 9 ++++-----
 arch/x86/um/user-offsets.c       | 2 +-
 2 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/arch/x86/um/os-Linux/registers.c b/arch/x86/um/os-Linux/registers.c
index 00f54a91bb4b..7265511d8e3b 100644
--- a/arch/x86/um/os-Linux/registers.c
+++ b/arch/x86/um/os-Linux/registers.c
@@ -30,7 +30,7 @@ int save_fp_registers(int pid, unsigned long *fp_regs)
 
 	if (have_xstate_support) {
 		iov.iov_base = fp_regs;
-		iov.iov_len = sizeof(struct _xstate);
+		iov.iov_len = FP_SIZE * sizeof(unsigned long);
 		if (ptrace(PTRACE_GETREGSET, pid, NT_X86_XSTATE, &iov) < 0)
 			return -errno;
 		return 0;
@@ -49,10 +49,9 @@ int restore_i387_registers(int pid, unsigned long *fp_regs)
 int restore_fp_registers(int pid, unsigned long *fp_regs)
 {
 	struct iovec iov;
-
 	if (have_xstate_support) {
 		iov.iov_base = fp_regs;
-		iov.iov_len = sizeof(struct _xstate);
+		iov.iov_len = FP_SIZE * sizeof(unsigned long);
 		if (ptrace(PTRACE_SETREGSET, pid, NT_X86_XSTATE, &iov) < 0)
 			return -errno;
 		return 0;
@@ -122,11 +121,11 @@ int put_fp_registers(int pid, unsigned long *regs)
 
 void arch_init_registers(int pid)
 {
-	struct _xstate fp_regs;
+	unsigned long fp_regs[FP_SIZE];
 	struct iovec iov;
 
 	iov.iov_base = &fp_regs;
-	iov.iov_len = sizeof(struct _xstate);
+	iov.iov_len = FP_SIZE * sizeof(unsigned long);
 	if (ptrace(PTRACE_GETREGSET, pid, NT_X86_XSTATE, &iov) == 0)
 		have_xstate_support = 1;
 }
diff --git a/arch/x86/um/user-offsets.c b/arch/x86/um/user-offsets.c
index cb3c22370cf5..c0111f093361 100644
--- a/arch/x86/um/user-offsets.c
+++ b/arch/x86/um/user-offsets.c
@@ -50,7 +50,7 @@ void foo(void)
 	DEFINE(HOST_GS, GS);
 	DEFINE(HOST_ORIG_AX, ORIG_EAX);
 #else
-	DEFINE(HOST_FP_SIZE, sizeof(struct _xstate) / sizeof(unsigned long));
+	DEFINE_LONGS(HOST_FP_SIZE, 2696);
 	DEFINE_LONGS(HOST_BX, RBX);
 	DEFINE_LONGS(HOST_CX, RCX);
 	DEFINE_LONGS(HOST_DI, RDI);
-- 
2.13.0


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

[Richard Weinberger]

On Thu, Jul 6, 2017 at 11:04 PM, Thomas Meyer <thomas@m3y3r.de> wrote:
> Hard code max size. Taken from
> https://sourceware.org/git/?p=binutils-gdb.git;a=blob;f=gdb/common/x86-xstate.h
>
> Signed-off-by: Thomas Meyer <thomas@m3y3r.de>
> ---
>  arch/x86/um/os-Linux/registers.c | 9 ++++-----
>  arch/x86/um/user-offsets.c       | 2 +-
>  2 files changed, 5 insertions(+), 6 deletions(-)

Applied. Thanks a lot for taking care of this nasty issue!

-- 
Thanks,
//richard

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

[Richard Weinberger]

On Fri, Jul 7, 2017 at 11:26 AM, Richard Weinberger
<richard.weinberger@gmail.com> wrote:
> On Thu, Jul 6, 2017 at 11:04 PM, Thomas Meyer <thomas@m3y3r.de> wrote:
>> Hard code max size. Taken from
>> https://sourceware.org/git/?p=binutils-gdb.git;a=blob;f=gdb/common/x86-xstate.h
>>
>> Signed-off-by: Thomas Meyer <thomas@m3y3r.de>
>> ---
>>  arch/x86/um/os-Linux/registers.c | 9 ++++-----
>>  arch/x86/um/user-offsets.c       | 2 +-
>>  2 files changed, 5 insertions(+), 6 deletions(-)
>
> Applied. Thanks a lot for taking care of this nasty issue!

Erm, did you notice the scary compiler warning produced by this commit? :-(

-- 
Thanks,
//richard

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[uml-devel] [PATCH] um: v2: Fix FP register size for XSTATE/XSAVE

[Thomas Meyer]

Hard code max size. Taken from
https://sourceware.org/git/?p=binutils-gdb.git;a=blob;f=gdb/common/x86-xstate.h

Signed-off-by: Thomas Meyer <thomas@m3y3r.de>
---
 arch/um/os-Linux/skas/process.c  | 22 ++++++++++++++++++----
 arch/x86/um/os-Linux/registers.c | 16 +++++++++++-----
 arch/x86/um/user-offsets.c       |  2 +-
 3 files changed, 30 insertions(+), 10 deletions(-)

diff --git a/arch/um/os-Linux/skas/process.c b/arch/um/os-Linux/skas/process.c
index 03b3c4cc7735..1a7cce387950 100644
--- a/arch/um/os-Linux/skas/process.c
+++ b/arch/um/os-Linux/skas/process.c
@@ -91,19 +91,25 @@ extern unsigned long current_stub_stack(void);
 static void get_skas_faultinfo(int pid, struct faultinfo *fi)
 {
 	int err;
-	unsigned long fpregs[FP_SIZE];
+	void * fpregs;
+
+	fpregs = malloc(FP_SIZE * sizeof(unsigned long));
+	if(fpregs == NULL) {
+		printk(UM_KERN_ERR "cannot alloc memory for save_fp_registers!");
+		goto errout;
+	}
 
 	err = get_fp_registers(pid, fpregs);
 	if (err < 0) {
 		printk(UM_KERN_ERR "save_fp_registers returned %d\n",
 		       err);
-		fatal_sigsegv();
+		goto errout;
 	}
 	err = ptrace(PTRACE_CONT, pid, 0, SIGSEGV);
 	if (err) {
 		printk(UM_KERN_ERR "Failed to continue stub, pid = %d, "
 		       "errno = %d\n", pid, errno);
-		fatal_sigsegv();
+		goto errout;
 	}
 	wait_stub_done(pid);
 
@@ -117,8 +123,16 @@ static void get_skas_faultinfo(int pid, struct faultinfo *fi)
 	if (err < 0) {
 		printk(UM_KERN_ERR "put_fp_registers returned %d\n",
 		       err);
-		fatal_sigsegv();
+		goto errout;
 	}
+	return;
+
+	errout:
+		if(fpregs != NULL) {
+			free(fpregs);
+		}
+		fatal_sigsegv();
+
 }
 
 static void handle_segv(int pid, struct uml_pt_regs * regs)
diff --git a/arch/x86/um/os-Linux/registers.c b/arch/x86/um/os-Linux/registers.c
index 00f54a91bb4b..e972c3d3b7b1 100644
--- a/arch/x86/um/os-Linux/registers.c
+++ b/arch/x86/um/os-Linux/registers.c
@@ -5,6 +5,7 @@
  */
 
 #include <errno.h>
+#include <stdlib.h>
 #include <sys/ptrace.h>
 #ifdef __i386__
 #include <sys/user.h>
@@ -30,7 +31,7 @@ int save_fp_registers(int pid, unsigned long *fp_regs)
 
 	if (have_xstate_support) {
 		iov.iov_base = fp_regs;
-		iov.iov_len = sizeof(struct _xstate);
+		iov.iov_len = FP_SIZE * sizeof(unsigned long);
 		if (ptrace(PTRACE_GETREGSET, pid, NT_X86_XSTATE, &iov) < 0)
 			return -errno;
 		return 0;
@@ -49,10 +50,9 @@ int restore_i387_registers(int pid, unsigned long *fp_regs)
 int restore_fp_registers(int pid, unsigned long *fp_regs)
 {
 	struct iovec iov;
-
 	if (have_xstate_support) {
 		iov.iov_base = fp_regs;
-		iov.iov_len = sizeof(struct _xstate);
+		iov.iov_len = FP_SIZE * sizeof(unsigned long);
 		if (ptrace(PTRACE_SETREGSET, pid, NT_X86_XSTATE, &iov) < 0)
 			return -errno;
 		return 0;
@@ -122,13 +122,19 @@ int put_fp_registers(int pid, unsigned long *regs)
 
 void arch_init_registers(int pid)
 {
-	struct _xstate fp_regs;
+	void * fp_regs;
 	struct iovec iov;
 
+	fp_regs = malloc(FP_SIZE * sizeof(unsigned long));
+	if(fp_regs == NULL)
+		return;
+
 	iov.iov_base = &fp_regs;
-	iov.iov_len = sizeof(struct _xstate);
+	iov.iov_len = FP_SIZE * sizeof(unsigned long);
 	if (ptrace(PTRACE_GETREGSET, pid, NT_X86_XSTATE, &iov) == 0)
 		have_xstate_support = 1;
+
+	free(fp_regs);
 }
 #endif
 
diff --git a/arch/x86/um/user-offsets.c b/arch/x86/um/user-offsets.c
index cb3c22370cf5..c0111f093361 100644
--- a/arch/x86/um/user-offsets.c
+++ b/arch/x86/um/user-offsets.c
@@ -50,7 +50,7 @@ void foo(void)
 	DEFINE(HOST_GS, GS);
 	DEFINE(HOST_ORIG_AX, ORIG_EAX);
 #else
-	DEFINE(HOST_FP_SIZE, sizeof(struct _xstate) / sizeof(unsigned long));
+	DEFINE_LONGS(HOST_FP_SIZE, 2696);
 	DEFINE_LONGS(HOST_BX, RBX);
 	DEFINE_LONGS(HOST_CX, RCX);
 	DEFINE_LONGS(HOST_DI, RDI);
-- 
2.13.0


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Re: [uml-devel] [PATCH] um: v2: Fix FP register size for XSTATE/XSAVE

[Richard Weinberger]

Thomas,

On Fri, Jul 7, 2017 at 11:01 PM, Thomas Meyer <thomas@m3y3r.de> wrote:
> Hard code max size. Taken from
> https://sourceware.org/git/?p=binutils-gdb.git;a=blob;f=gdb/common/x86-xstate.h
>
> Signed-off-by: Thomas Meyer <thomas@m3y3r.de>
> ---
>  arch/um/os-Linux/skas/process.c  | 22 ++++++++++++++++++----
>  arch/x86/um/os-Linux/registers.c | 16 +++++++++++-----
>  arch/x86/um/user-offsets.c       |  2 +-
>  3 files changed, 30 insertions(+), 10 deletions(-)
>
> diff --git a/arch/um/os-Linux/skas/process.c b/arch/um/os-Linux/skas/process.c
> index 03b3c4cc7735..1a7cce387950 100644
> --- a/arch/um/os-Linux/skas/process.c
> +++ b/arch/um/os-Linux/skas/process.c
> @@ -91,19 +91,25 @@ extern unsigned long current_stub_stack(void);
>  static void get_skas_faultinfo(int pid, struct faultinfo *fi)
>  {
>         int err;
> -       unsigned long fpregs[FP_SIZE];
> +       void * fpregs;
> +
> +       fpregs = malloc(FP_SIZE * sizeof(unsigned long));
> +       if(fpregs == NULL) {
> +               printk(UM_KERN_ERR "cannot alloc memory for save_fp_registers!");
> +               goto errout;
> +       }

Having a malloc() here is rather expensive.
I suggest to allocate a buffer in userspace() that can be used in
get_skas_faultinfo().

Thanks,
//richard
-- 
Thanks,
//richard

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

[Thomas Meyer]

Hard code max size. Taken from
https://sourceware.org/git/?p=binutils-gdb.git;a=blob;f=gdb/common/x86-xstate.h

v3: use static fp_regs for get_skas_faultinfo

Signed-off-by: Thomas Meyer <thomas@m3y3r.de>
---
 arch/um/os-Linux/skas/process.c  |  7 ++++---
 arch/x86/um/os-Linux/registers.c | 18 ++++++++++++------
 arch/x86/um/user-offsets.c       |  2 +-
 3 files changed, 17 insertions(+), 10 deletions(-)

diff --git a/arch/um/os-Linux/skas/process.c b/arch/um/os-Linux/skas/process.c
index 03b3c4cc7735..b5fdef795985 100644
--- a/arch/um/os-Linux/skas/process.c
+++ b/arch/um/os-Linux/skas/process.c
@@ -88,12 +88,13 @@ void wait_stub_done(int pid)
 
 extern unsigned long current_stub_stack(void);
 
+static unsigned long skas_faultinfo_fpregs[FP_SIZE];
+
 static void get_skas_faultinfo(int pid, struct faultinfo *fi)
 {
 	int err;
-	unsigned long fpregs[FP_SIZE];
 
-	err = get_fp_registers(pid, fpregs);
+	err = get_fp_registers(pid, skas_faultinfo_fpregs);
 	if (err < 0) {
 		printk(UM_KERN_ERR "save_fp_registers returned %d\n",
 		       err);
@@ -113,7 +114,7 @@ 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, skas_faultinfo_fpregs);
 	if (err < 0) {
 		printk(UM_KERN_ERR "put_fp_registers returned %d\n",
 		       err);
diff --git a/arch/x86/um/os-Linux/registers.c b/arch/x86/um/os-Linux/registers.c
index 00f54a91bb4b..2717911d1bef 100644
--- a/arch/x86/um/os-Linux/registers.c
+++ b/arch/x86/um/os-Linux/registers.c
@@ -5,6 +5,7 @@
  */
 
 #include <errno.h>
+#include <stdlib.h>
 #include <sys/ptrace.h>
 #ifdef __i386__
 #include <sys/user.h>
@@ -30,7 +31,7 @@ int save_fp_registers(int pid, unsigned long *fp_regs)
 
 	if (have_xstate_support) {
 		iov.iov_base = fp_regs;
-		iov.iov_len = sizeof(struct _xstate);
+		iov.iov_len = FP_SIZE * sizeof(unsigned long);
 		if (ptrace(PTRACE_GETREGSET, pid, NT_X86_XSTATE, &iov) < 0)
 			return -errno;
 		return 0;
@@ -49,10 +50,9 @@ int restore_i387_registers(int pid, unsigned long *fp_regs)
 int restore_fp_registers(int pid, unsigned long *fp_regs)
 {
 	struct iovec iov;
-
 	if (have_xstate_support) {
 		iov.iov_base = fp_regs;
-		iov.iov_len = sizeof(struct _xstate);
+		iov.iov_len = FP_SIZE * sizeof(unsigned long);
 		if (ptrace(PTRACE_SETREGSET, pid, NT_X86_XSTATE, &iov) < 0)
 			return -errno;
 		return 0;
@@ -122,13 +122,19 @@ int put_fp_registers(int pid, unsigned long *regs)
 
 void arch_init_registers(int pid)
 {
-	struct _xstate fp_regs;
+	void * fp_regs;
 	struct iovec iov;
 
-	iov.iov_base = &fp_regs;
-	iov.iov_len = sizeof(struct _xstate);
+	fp_regs = malloc(FP_SIZE * sizeof(unsigned long));
+	if(fp_regs == NULL)
+		return;
+
+	iov.iov_base = fp_regs;
+	iov.iov_len = FP_SIZE * sizeof(unsigned long);
 	if (ptrace(PTRACE_GETREGSET, pid, NT_X86_XSTATE, &iov) == 0)
 		have_xstate_support = 1;
+
+	free(fp_regs);
 }
 #endif
 
diff --git a/arch/x86/um/user-offsets.c b/arch/x86/um/user-offsets.c
index cb3c22370cf5..c0111f093361 100644
--- a/arch/x86/um/user-offsets.c
+++ b/arch/x86/um/user-offsets.c
@@ -50,7 +50,7 @@ void foo(void)
 	DEFINE(HOST_GS, GS);
 	DEFINE(HOST_ORIG_AX, ORIG_EAX);
 #else
-	DEFINE(HOST_FP_SIZE, sizeof(struct _xstate) / sizeof(unsigned long));
+	DEFINE_LONGS(HOST_FP_SIZE, 2696);
 	DEFINE_LONGS(HOST_BX, RBX);
 	DEFINE_LONGS(HOST_CX, RCX);
 	DEFINE_LONGS(HOST_DI, RDI);
-- 
2.13.0


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

[Richard Weinberger]

Thomas,

Am 10.07.2017 um 00:33 schrieb Thomas Meyer:
> Hard code max size. Taken from
> https://sourceware.org/git/?p=binutils-gdb.git;a=blob;f=gdb/common/x86-xstate.h
> 
> v3: use static fp_regs for get_skas_faultinfo
> 
> Signed-off-by: Thomas Meyer <thomas@m3y3r.de>
> ---
>  arch/um/os-Linux/skas/process.c  |  7 ++++---
>  arch/x86/um/os-Linux/registers.c | 18 ++++++++++++------
>  arch/x86/um/user-offsets.c       |  2 +-
>  3 files changed, 17 insertions(+), 10 deletions(-)
> 
> diff --git a/arch/um/os-Linux/skas/process.c b/arch/um/os-Linux/skas/process.c
> index 03b3c4cc7735..b5fdef795985 100644
> --- a/arch/um/os-Linux/skas/process.c
> +++ b/arch/um/os-Linux/skas/process.c
> @@ -88,12 +88,13 @@ void wait_stub_done(int pid)
>  
>  extern unsigned long current_stub_stack(void);
>  
> +static unsigned long skas_faultinfo_fpregs[FP_SIZE];
> +

Uhmm, are you sure that this does not race with other userspace() instances?

Thanks,
//richard

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