[PATCH v2 0/3] powerpc/fsl: Speculation barrier for NXP PowerPC Book3E

[PATCH v2 0/3] powerpc/fsl: Speculation barrier for NXP PowerPC Book3E

[Diana Craciun]

Implement barrier_nospec for NXP PowerPC Book3E processors. 

Diana Craciun (3):
  Disable the speculation barrier from the command line
  Add barrier_nospec implementation for NXP PowerPC Book3E
  Implement cpu_show_spectre_v1/v2 for NXP PowerPC Book3E

 arch/powerpc/Kconfig               |  2 +-
 arch/powerpc/include/asm/barrier.h | 10 +++++++++
 arch/powerpc/include/asm/setup.h   |  2 +-
 arch/powerpc/kernel/Makefile       |  2 +-
 arch/powerpc/kernel/module.c       |  5 +++--
 arch/powerpc/kernel/security.c     | 42 +++++++++++++++++++++++++++++++++++++-
 arch/powerpc/kernel/setup_32.c     |  5 +++++
 arch/powerpc/kernel/setup_64.c     |  6 ++++++
 arch/powerpc/kernel/vmlinux.lds.S  |  4 +++-
 arch/powerpc/lib/feature-fixups.c  | 35 ++++++++++++++++++++++++++++++-
 10 files changed, 105 insertions(+), 8 deletions(-)

--
History:

v1 --> v2
- added implementation for cpu_show_spectre_x functions
- the mitigation is no longer enabled through device tree options
2.5.5

[PATCH v2 1/3] powerpc/fsl: Disable the speculation barrier from the command line

[Diana Craciun]

The speculation barrier can be disabled from the command line
with the parameter: "nospectre_v1".

Signed-off-by: Diana Craciun <diana.craciun@nxp.com>
---
 arch/powerpc/kernel/security.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/security.c b/arch/powerpc/kernel/security.c
index 3eb9c45..c55e102 100644
--- a/arch/powerpc/kernel/security.c
+++ b/arch/powerpc/kernel/security.c
@@ -16,6 +16,7 @@
 unsigned long powerpc_security_features __read_mostly = SEC_FTR_DEFAULT;
 
 bool barrier_nospec_enabled;
+static bool no_nospec;
 
 static void enable_barrier_nospec(bool enable)
 {
@@ -42,9 +43,18 @@ void setup_barrier_nospec(void)
 	enable = security_ftr_enabled(SEC_FTR_FAVOUR_SECURITY) &&
 		 security_ftr_enabled(SEC_FTR_BNDS_CHK_SPEC_BAR);
 
-	enable_barrier_nospec(enable);
+	if (!no_nospec)
+		enable_barrier_nospec(enable);
 }
 
+static int __init handle_nospectre_v1(char *p)
+{
+	no_nospec = true;
+
+	return 0;
+}
+early_param("nospectre_v1", handle_nospectre_v1);
+
 #ifdef CONFIG_DEBUG_FS
 static int barrier_nospec_set(void *data, u64 val)
 {
-- 
2.5.5

[PATCH v2 2/3] powerpc/fsl: Add barrier_nospec implementation for NXP PowerPC Book3E

[Diana Craciun]

Implement the barrier_nospec as a isync;sync instruction sequence.
The implementation uses the infrastructure built for BOOK3S 64.

Signed-off-by: Diana Craciun <diana.craciun@nxp.com>
---
 arch/powerpc/include/asm/barrier.h | 10 ++++++++++
 arch/powerpc/include/asm/setup.h   |  2 +-
 arch/powerpc/kernel/Makefile       |  2 +-
 arch/powerpc/kernel/module.c       |  5 +++--
 arch/powerpc/kernel/security.c     | 15 +++++++++++++++
 arch/powerpc/kernel/setup_32.c     |  5 +++++
 arch/powerpc/kernel/setup_64.c     |  6 ++++++
 arch/powerpc/kernel/vmlinux.lds.S  |  4 +++-
 arch/powerpc/lib/feature-fixups.c  | 35 ++++++++++++++++++++++++++++++++++-
 9 files changed, 78 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/include/asm/barrier.h b/arch/powerpc/include/asm/barrier.h
index f67b3f6..405d572 100644
--- a/arch/powerpc/include/asm/barrier.h
+++ b/arch/powerpc/include/asm/barrier.h
@@ -86,6 +86,16 @@ do {									\
 // This also acts as a compiler barrier due to the memory clobber.
 #define barrier_nospec() asm (stringify_in_c(barrier_nospec_asm) ::: "memory")
 
+#elif defined(CONFIG_PPC_FSL_BOOK3E)
+/*
+ * Prevent the execution of subsequent instructions speculatively using a
+ * isync;sync instruction sequence.
+ */
+#define barrier_nospec_asm NOSPEC_BARRIER_FIXUP_SECTION; nop; nop
+
+// This also acts as a compiler barrier due to the memory clobber.
+#define barrier_nospec() asm (stringify_in_c(barrier_nospec_asm) ::: "memory")
+
 #else /* !CONFIG_PPC_BOOK3S_64 */
 #define barrier_nospec_asm
 #define barrier_nospec()
diff --git a/arch/powerpc/include/asm/setup.h b/arch/powerpc/include/asm/setup.h
index 8721fd0..67a2810 100644
--- a/arch/powerpc/include/asm/setup.h
+++ b/arch/powerpc/include/asm/setup.h
@@ -56,7 +56,7 @@ void setup_barrier_nospec(void);
 void do_barrier_nospec_fixups(bool enable);
 extern bool barrier_nospec_enabled;
 
-#ifdef CONFIG_PPC_BOOK3S_64
+#if defined(CONFIG_PPC_BOOK3S_64) || defined(CONFIG_PPC_FSL_BOOK3E)
 void do_barrier_nospec_fixups_range(bool enable, void *start, void *end);
 #else
 static inline void do_barrier_nospec_fixups_range(bool enable, void *start, void *end) { };
diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
index 2b4c40b2..d9dee43 100644
--- a/arch/powerpc/kernel/Makefile
+++ b/arch/powerpc/kernel/Makefile
@@ -76,7 +76,7 @@ endif
 obj64-$(CONFIG_HIBERNATION)	+= swsusp_asm64.o
 obj-$(CONFIG_MODULES)		+= module.o module_$(BITS).o
 obj-$(CONFIG_44x)		+= cpu_setup_44x.o
-obj-$(CONFIG_PPC_FSL_BOOK3E)	+= cpu_setup_fsl_booke.o
+obj-$(CONFIG_PPC_FSL_BOOK3E)	+= cpu_setup_fsl_booke.o security.o
 obj-$(CONFIG_PPC_DOORBELL)	+= dbell.o
 obj-$(CONFIG_JUMP_LABEL)	+= jump_label.o
 
diff --git a/arch/powerpc/kernel/module.c b/arch/powerpc/kernel/module.c
index 1b3c683..96a9821 100644
--- a/arch/powerpc/kernel/module.c
+++ b/arch/powerpc/kernel/module.c
@@ -72,13 +72,14 @@ int module_finalize(const Elf_Ehdr *hdr,
 		do_feature_fixups(powerpc_firmware_features,
 				  (void *)sect->sh_addr,
 				  (void *)sect->sh_addr + sect->sh_size);
-
+#endif /* CONFIG_PPC64 */
+#if defined(CONFIG_PPC64) || defined(CONFIG_PPC_FSL_BOOK3E)
 	sect = find_section(hdr, sechdrs, "__spec_barrier_fixup");
 	if (sect != NULL)
 		do_barrier_nospec_fixups_range(barrier_nospec_enabled,
 				  (void *)sect->sh_addr,
 				  (void *)sect->sh_addr + sect->sh_size);
-#endif
+#endif /* CONFIG_PPC64 || CONFIG_PPC_FSL_BOOK3E */
 
 	sect = find_section(hdr, sechdrs, "__lwsync_fixup");
 	if (sect != NULL)
diff --git a/arch/powerpc/kernel/security.c b/arch/powerpc/kernel/security.c
index c55e102..797c975 100644
--- a/arch/powerpc/kernel/security.c
+++ b/arch/powerpc/kernel/security.c
@@ -13,7 +13,9 @@
 #include <asm/setup.h>
 
 
+#ifdef CONFIG_PPC_BOOK3S_64
 unsigned long powerpc_security_features __read_mostly = SEC_FTR_DEFAULT;
+#endif /* CONFIG_PPC_BOOK3S_64 */
 
 bool barrier_nospec_enabled;
 static bool no_nospec;
@@ -24,6 +26,7 @@ static void enable_barrier_nospec(bool enable)
 	do_barrier_nospec_fixups(enable);
 }
 
+#ifdef CONFIG_PPC_BOOK3S_64
 void setup_barrier_nospec(void)
 {
 	bool enable;
@@ -46,6 +49,15 @@ void setup_barrier_nospec(void)
 	if (!no_nospec)
 		enable_barrier_nospec(enable);
 }
+#endif /* CONFIG_PPC_BOOK3S_64 */
+
+#ifdef CONFIG_PPC_FSL_BOOK3E
+void setup_barrier_nospec(void)
+{
+	if (!no_nospec)
+		enable_barrier_nospec(true);
+}
+#endif /* CONFIG_PPC_FSL_BOOK3E */
 
 static int __init handle_nospectre_v1(char *p)
 {
@@ -92,6 +104,7 @@ static __init int barrier_nospec_debugfs_init(void)
 device_initcall(barrier_nospec_debugfs_init);
 #endif /* CONFIG_DEBUG_FS */
 
+#ifdef CONFIG_PPC_BOOK3S_64
 ssize_t cpu_show_meltdown(struct device *dev, struct device_attribute *attr, char *buf)
 {
 	bool thread_priv;
@@ -168,3 +181,5 @@ ssize_t cpu_show_spectre_v2(struct device *dev, struct device_attribute *attr, c
 
 	return s.len;
 }
+#endif /* CONFIG_PPC_BOOK3S_64 */
+
diff --git a/arch/powerpc/kernel/setup_32.c b/arch/powerpc/kernel/setup_32.c
index 7445748..80c1e6e 100644
--- a/arch/powerpc/kernel/setup_32.c
+++ b/arch/powerpc/kernel/setup_32.c
@@ -116,6 +116,11 @@ notrace void __init machine_init(u64 dt_ptr)
 	/* Do some early initialization based on the flat device tree */
 	early_init_devtree(__va(dt_ptr));
 
+	/* Apply the speculation barrier fixup */
+#ifdef CONFIG_PPC_FSL_BOOK3E
+	setup_barrier_nospec();
+#endif
+
 	early_init_mmu();
 
 	setup_kdump_trampoline();
diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index 7a7ce8a..b2a644a 100644
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -327,6 +327,12 @@ void __init early_setup(unsigned long dt_ptr)
 
 	/* Apply all the dynamic patching */
 	apply_feature_fixups();
+
+	/* Apply the speculation barrier fixup */
+#ifdef CONFIG_PPC_FSL_BOOK3E
+	setup_barrier_nospec();
+#endif /* CONFIG_PPC_FSL_BOOK3E */
+
 	setup_feature_keys();
 
 	/* Initialize the hash table or TLB handling */
diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S
index ff73f49..af513e6 100644
--- a/arch/powerpc/kernel/vmlinux.lds.S
+++ b/arch/powerpc/kernel/vmlinux.lds.S
@@ -139,14 +139,16 @@ SECTIONS
 		*(__rfi_flush_fixup)
 		__stop___rfi_flush_fixup = .;
 	}
+#endif /* CONFIG_PPC64 */
 
+#if defined(CONFIG_PPC64) || defined(CONFIG_PPC_FSL_BOOK3E)
 	. = ALIGN(8);
 	__spec_barrier_fixup : AT(ADDR(__spec_barrier_fixup) - LOAD_OFFSET) {
 		__start___barrier_nospec_fixup = .;
 		*(__barrier_nospec_fixup)
 		__stop___barrier_nospec_fixup = .;
 	}
-#endif
+#endif /* CONFIG_PPC64 || CONFIG_PPC_FSL_BOOK3E */
 
 	EXCEPTION_TABLE(0)
 
diff --git a/arch/powerpc/lib/feature-fixups.c b/arch/powerpc/lib/feature-fixups.c
index 2b9173d..bea2b87 100644
--- a/arch/powerpc/lib/feature-fixups.c
+++ b/arch/powerpc/lib/feature-fixups.c
@@ -188,7 +188,40 @@ void do_barrier_nospec_fixups_range(bool enable, void *fixup_start, void *fixup_
 
 	printk(KERN_DEBUG "barrier-nospec: patched %d locations\n", i);
 }
+#endif /* CONFIG_PPC_BOOK3S_64 */
+
+#ifdef CONFIG_PPC_FSL_BOOK3E
+void do_barrier_nospec_fixups_range(bool enable, void *fixup_start, void *fixup_end)
+{
+	unsigned int instr[2], *dest;
+	long *start, *end;
+	int i;
+
+	start = fixup_start;
+	end = fixup_end;
+
+	instr[0] = PPC_INST_NOP;
+	instr[1] = PPC_INST_NOP;
+
+	if (enable) {
+		pr_info("barrier_nospec; using isync; sync as a speculation barrier\n");
+		instr[0] = PPC_INST_ISYNC;
+		instr[1] = PPC_INST_SYNC;
+	}
+
+	for (i = 0; start < end; start++, i++) {
+		dest = (void *)start + *start;
+		pr_devel("patching dest %lx\n", (unsigned long)dest);
 
+		patch_instruction(dest, instr[0]);
+		patch_instruction(dest + 1, instr[1]);
+	}
+
+	pr_debug("barrier-nospec: patched %d locations\n", i);
+}
+#endif /* CONFIG_PPC_FSL_BOOK3E */
+
+#if defined(CONFIG_PPC_BOOK3S_64) || defined(CONFIG_PPC_FSL_BOOK3E)
 void do_barrier_nospec_fixups(bool enable)
 {
 	void *start, *end;
@@ -199,7 +232,7 @@ void do_barrier_nospec_fixups(bool enable)
 	do_barrier_nospec_fixups_range(enable, start, end);
 }
 
-#endif /* CONFIG_PPC_BOOK3S_64 */
+#endif /* CONFIG_PPC_BOOK3S_64 || CONFIG_PPC_FSL_BOOK3E */
 
 void do_lwsync_fixups(unsigned long value, void *fixup_start, void *fixup_end)
 {
-- 
2.5.5

[PATCH v2 3/3] powerpc/fsl: Implement cpu_show_spectre_v1/v2 for NXP PowerPC Book3E

[Diana Craciun]

Signed-off-by: Diana Craciun <diana.craciun@nxp.com>
---
 arch/powerpc/Kconfig           |  2 +-
 arch/powerpc/kernel/security.c | 15 +++++++++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 940c955..a781d60 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -170,7 +170,7 @@ config PPC
 	select GENERIC_CLOCKEVENTS_BROADCAST	if SMP
 	select GENERIC_CMOS_UPDATE
 	select GENERIC_CPU_AUTOPROBE
-	select GENERIC_CPU_VULNERABILITIES	if PPC_BOOK3S_64
+	select GENERIC_CPU_VULNERABILITIES	if PPC_BOOK3S_64 || PPC_FSL_BOOK3E
 	select GENERIC_IRQ_SHOW
 	select GENERIC_IRQ_SHOW_LEVEL
 	select GENERIC_SMP_IDLE_THREAD
diff --git a/arch/powerpc/kernel/security.c b/arch/powerpc/kernel/security.c
index 797c975..aceaadc 100644
--- a/arch/powerpc/kernel/security.c
+++ b/arch/powerpc/kernel/security.c
@@ -183,3 +183,18 @@ ssize_t cpu_show_spectre_v2(struct device *dev, struct device_attribute *attr, c
 }
 #endif /* CONFIG_PPC_BOOK3S_64 */
 
+#ifdef CONFIG_PPC_FSL_BOOK3E
+ssize_t cpu_show_spectre_v1(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	if (barrier_nospec_enabled)
+		return sprintf(buf, "Mitigation: __user pointer sanitization\n");
+
+	return sprintf(buf, "Vulnerable\n");
+}
+
+ssize_t cpu_show_spectre_v2(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	return sprintf(buf, "Vulnerable\n");
+}
+#endif /* CONFIG_PPC_FSL_BOOK3E */
+
-- 
2.5.5

RE: [PATCH v2 3/3] powerpc/fsl: Implement cpu_show_spectre_v1/v2 for NXP PowerPC Book3E

[Bharat Bhushan]

Hi Diana,

> -----Original Message-----
> From: Diana Craciun [mailto:diana.craciun@nxp.com]
> Sent: Monday, June 11, 2018 6:23 PM
> To: linuxppc-dev@lists.ozlabs.org
> Cc: mpe@ellerman.id.au; oss@buserror.net; Leo Li <leoyang.li@nxp.com>;
> Bharat Bhushan <bharat.bhushan@nxp.com>; Diana Madalina Craciun
> <diana.craciun@nxp.com>
> Subject: [PATCH v2 3/3] powerpc/fsl: Implement cpu_show_spectre_v1/v2 for
> NXP PowerPC Book3E

Please add some description

>=20
> Signed-off-by: Diana Craciun <diana.craciun@nxp.com>
> ---
>  arch/powerpc/Kconfig           |  2 +-
>  arch/powerpc/kernel/security.c | 15 +++++++++++++++
>  2 files changed, 16 insertions(+), 1 deletion(-)
>=20
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index
> 940c955..a781d60 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -170,7 +170,7 @@ config PPC
>  	select GENERIC_CLOCKEVENTS_BROADCAST	if SMP
>  	select GENERIC_CMOS_UPDATE
>  	select GENERIC_CPU_AUTOPROBE
> -	select GENERIC_CPU_VULNERABILITIES	if PPC_BOOK3S_64
> +	select GENERIC_CPU_VULNERABILITIES	if PPC_BOOK3S_64 ||
> PPC_FSL_BOOK3E
>  	select GENERIC_IRQ_SHOW
>  	select GENERIC_IRQ_SHOW_LEVEL
>  	select GENERIC_SMP_IDLE_THREAD
> diff --git a/arch/powerpc/kernel/security.c b/arch/powerpc/kernel/securit=
y.c
> index 797c975..aceaadc 100644
> --- a/arch/powerpc/kernel/security.c
> +++ b/arch/powerpc/kernel/security.c
> @@ -183,3 +183,18 @@ ssize_t cpu_show_spectre_v2(struct device *dev,
> struct device_attribute *attr, c  }  #endif /* CONFIG_PPC_BOOK3S_64 */
>=20
> +#ifdef CONFIG_PPC_FSL_BOOK3E
> +ssize_t cpu_show_spectre_v1(struct device *dev, struct device_attribute
> +*attr, char *buf) {
> +	if (barrier_nospec_enabled)
> +		return sprintf(buf, "Mitigation: __user pointer sanitization\n");
> +
> +	return sprintf(buf, "Vulnerable\n");
> +}
> +
> +ssize_t cpu_show_spectre_v2(struct device *dev, struct device_attribute
> +*attr, char *buf) {
> +	return sprintf(buf, "Vulnerable\n");
> +}
> +#endif /* CONFIG_PPC_FSL_BOOK3E */
> +
> --
> 2.5.5

Re: [PATCH v2 3/3] powerpc/fsl: Implement cpu_show_spectre_v1/v2 for NXP PowerPC Book3E

[Michal Suchánek]

On Tue, 12 Jun 2018 02:59:11 +0000
Bharat Bhushan <bharat.bhushan@nxp.com> wrote:

> Hi Diana,
> 
> > -----Original Message-----
> > From: Diana Craciun [mailto:diana.craciun@nxp.com]
> > Sent: Monday, June 11, 2018 6:23 PM
> > To: linuxppc-dev@lists.ozlabs.org
> > Cc: mpe@ellerman.id.au; oss@buserror.net; Leo Li
> > <leoyang.li@nxp.com>; Bharat Bhushan <bharat.bhushan@nxp.com>;
> > Diana Madalina Craciun <diana.craciun@nxp.com>
> > Subject: [PATCH v2 3/3] powerpc/fsl: Implement
> > cpu_show_spectre_v1/v2 for NXP PowerPC Book3E  
> 
> Please add some description

To me the subject is self-explanatory. It implements a kernel interface
that was already described elsewhere.

What are you missing here?

Thanks

Michal

> 
> > 
> > Signed-off-by: Diana Craciun <diana.craciun@nxp.com>
> > ---
> >  arch/powerpc/Kconfig           |  2 +-
> >  arch/powerpc/kernel/security.c | 15 +++++++++++++++
> >  2 files changed, 16 insertions(+), 1 deletion(-)
> > 
> > diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index
> > 940c955..a781d60 100644
> > --- a/arch/powerpc/Kconfig
> > +++ b/arch/powerpc/Kconfig
> > @@ -170,7 +170,7 @@ config PPC
> >  	select GENERIC_CLOCKEVENTS_BROADCAST	if SMP
> >  	select GENERIC_CMOS_UPDATE
> >  	select GENERIC_CPU_AUTOPROBE
> > -	select GENERIC_CPU_VULNERABILITIES	if PPC_BOOK3S_64
> > +	select GENERIC_CPU_VULNERABILITIES	if PPC_BOOK3S_64
> > || PPC_FSL_BOOK3E
> >  	select GENERIC_IRQ_SHOW
> >  	select GENERIC_IRQ_SHOW_LEVEL
> >  	select GENERIC_SMP_IDLE_THREAD
> > diff --git a/arch/powerpc/kernel/security.c
> > b/arch/powerpc/kernel/security.c index 797c975..aceaadc 100644
> > --- a/arch/powerpc/kernel/security.c
> > +++ b/arch/powerpc/kernel/security.c
> > @@ -183,3 +183,18 @@ ssize_t cpu_show_spectre_v2(struct device *dev,
> > struct device_attribute *attr, c  }  #endif /* CONFIG_PPC_BOOK3S_64
> > */
> > 
> > +#ifdef CONFIG_PPC_FSL_BOOK3E
> > +ssize_t cpu_show_spectre_v1(struct device *dev, struct
> > device_attribute +*attr, char *buf) {
> > +	if (barrier_nospec_enabled)
> > +		return sprintf(buf, "Mitigation: __user pointer
> > sanitization\n"); +
> > +	return sprintf(buf, "Vulnerable\n");
> > +}
> > +
> > +ssize_t cpu_show_spectre_v2(struct device *dev, struct
> > device_attribute +*attr, char *buf) {
> > +	return sprintf(buf, "Vulnerable\n");
> > +}
> > +#endif /* CONFIG_PPC_FSL_BOOK3E */
> > +
> > --
> > 2.5.5  
> 

Re: [PATCH v2 0/3] powerpc/fsl: Speculation barrier for NXP PowerPC Book3E

[Diana Madalina Craciun]

Hi,=0A=
=0A=
Should I rebase the series on top of the latest kernel?=0A=
=0A=
Diana=0A=
=0A=
On 6/11/2018 3:53 PM, Diana Craciun wrote:=0A=
> Implement barrier_nospec for NXP PowerPC Book3E processors. =0A=
>=0A=
> Diana Craciun (3):=0A=
>   Disable the speculation barrier from the command line=0A=
>   Add barrier_nospec implementation for NXP PowerPC Book3E=0A=
>   Implement cpu_show_spectre_v1/v2 for NXP PowerPC Book3E=0A=
>=0A=
>  arch/powerpc/Kconfig               |  2 +-=0A=
>  arch/powerpc/include/asm/barrier.h | 10 +++++++++=0A=
>  arch/powerpc/include/asm/setup.h   |  2 +-=0A=
>  arch/powerpc/kernel/Makefile       |  2 +-=0A=
>  arch/powerpc/kernel/module.c       |  5 +++--=0A=
>  arch/powerpc/kernel/security.c     | 42 ++++++++++++++++++++++++++++++++=
+++++-=0A=
>  arch/powerpc/kernel/setup_32.c     |  5 +++++=0A=
>  arch/powerpc/kernel/setup_64.c     |  6 ++++++=0A=
>  arch/powerpc/kernel/vmlinux.lds.S  |  4 +++-=0A=
>  arch/powerpc/lib/feature-fixups.c  | 35 ++++++++++++++++++++++++++++++-=
=0A=
>  10 files changed, 105 insertions(+), 8 deletions(-)=0A=
>=0A=
> --=0A=
> History:=0A=
>=0A=
> v1 --> v2=0A=
> - added implementation for cpu_show_spectre_x functions=0A=
> - the mitigation is no longer enabled through device tree options=0A=
> 2.5.5=0A=
>=0A=
>=0A=
=0A=

Re: [PATCH v2 1/3] powerpc/fsl: Disable the speculation barrier from the command line

[Michael Ellerman]

Diana Craciun <diana.craciun@nxp.com> writes:

> The speculation barrier can be disabled from the command line
> with the parameter: "nospectre_v1".

Can you please send another patch adding it to Documentation/admin-guide/kernel-parameters.txt

You should mark it as "PPC" only for now.

cheers

Re: [PATCH v2 3/3] powerpc/fsl: Implement cpu_show_spectre_v1/v2 for NXP PowerPC Book3E

[Michael Ellerman]

Michal Such=C3=A1nek <msuchanek@suse.de> writes:
> On Tue, 12 Jun 2018 02:59:11 +0000
> Bharat Bhushan <bharat.bhushan@nxp.com> wrote:
>
>> Hi Diana,
>>=20
>> > -----Original Message-----
>> > From: Diana Craciun [mailto:diana.craciun@nxp.com]
>> > Sent: Monday, June 11, 2018 6:23 PM
>> > To: linuxppc-dev@lists.ozlabs.org
>> > Cc: mpe@ellerman.id.au; oss@buserror.net; Leo Li
>> > <leoyang.li@nxp.com>; Bharat Bhushan <bharat.bhushan@nxp.com>;
>> > Diana Madalina Craciun <diana.craciun@nxp.com>
>> > Subject: [PATCH v2 3/3] powerpc/fsl: Implement
>> > cpu_show_spectre_v1/v2 for NXP PowerPC Book3E=20=20
>>=20
>> Please add some description
>
> To me the subject is self-explanatory. It implements a kernel interface
> that was already described elsewhere.
>
> What are you missing here?

It should at least explain why it's reimplementing a function that
already exists for powerpc. ie. Why can't the existing version be used?

cheers

Re: [PATCH v2 2/3] powerpc/fsl: Add barrier_nospec implementation for NXP PowerPC Book3E

[Michael Ellerman]

Hi Diana,

A few comments below ...

Diana Craciun <diana.craciun@nxp.com> writes:
> Implement the barrier_nospec as a isync;sync instruction sequence.
> The implementation uses the infrastructure built for BOOK3S 64.

Do you have any details on why that sequence functions as an effective
barrier on your chips?

In a lot of places we have eg:

 +#if defined(CONFIG_PPC_BOOK3S_64) || defined(CONFIG_PPC_FSL_BOOK3E)

Can you please add a Kconfig symbol to capture that. eg.

config PPC_NOSPEC
	bool
        default y
	depends on PPC_BOOK3S_64 || PPC_FSL_BOOK3E


And then use that everywhere.

> diff --git a/arch/powerpc/include/asm/barrier.h b/arch/powerpc/include/asm/barrier.h
> index f67b3f6..405d572 100644
> --- a/arch/powerpc/include/asm/barrier.h
> +++ b/arch/powerpc/include/asm/barrier.h
> @@ -86,6 +86,16 @@ do {									\
>  // This also acts as a compiler barrier due to the memory clobber.
>  #define barrier_nospec() asm (stringify_in_c(barrier_nospec_asm) ::: "memory")
>  
> +#elif defined(CONFIG_PPC_FSL_BOOK3E)
> +/*
> + * Prevent the execution of subsequent instructions speculatively using a
> + * isync;sync instruction sequence.
> + */
> +#define barrier_nospec_asm NOSPEC_BARRIER_FIXUP_SECTION; nop; nop
> +
> +// This also acts as a compiler barrier due to the memory clobber.
> +#define barrier_nospec() asm (stringify_in_c(barrier_nospec_asm) ::: "memory")
> +
>  #else /* !CONFIG_PPC_BOOK3S_64 */
>  #define barrier_nospec_asm
>  #define barrier_nospec()

If we have CONFIG_PPC_NOSPEC this can be done something like:

#ifdef CONFIG_PPC_BOOK3S_64
#define NOSPEC_BARRIER_SLOT	nop
#elif defined(CONFIG_PPC_FSL_BOOK3E)
#define NOSPEC_BARRIER_SLOT	nop; nop
#endif /* CONFIG_PPC_BOOK3S_64 */

#ifdef CONFIG_PPC_NOSPEC
/*
 * Prevent execution of subsequent instructions until preceding branches have
 * been fully resolved and are no longer executing speculatively.
 */
#define barrier_nospec_asm NOSPEC_BARRIER_FIXUP_SECTION; NOSPEC_BARRIER_SLOT

// This also acts as a compiler barrier due to the memory clobber.
#define barrier_nospec() asm (stringify_in_c(barrier_nospec_asm) ::: "memory")
#else
#define barrier_nospec_asm
#define barrier_nospec()
#endif /* CONFIG_PPC_NOSPEC */


> diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
> index 2b4c40b2..d9dee43 100644
> --- a/arch/powerpc/kernel/Makefile
> +++ b/arch/powerpc/kernel/Makefile
> @@ -76,7 +76,7 @@ endif
>  obj64-$(CONFIG_HIBERNATION)	+= swsusp_asm64.o
>  obj-$(CONFIG_MODULES)		+= module.o module_$(BITS).o
>  obj-$(CONFIG_44x)		+= cpu_setup_44x.o
> -obj-$(CONFIG_PPC_FSL_BOOK3E)	+= cpu_setup_fsl_booke.o
> +obj-$(CONFIG_PPC_FSL_BOOK3E)	+= cpu_setup_fsl_booke.o security.o
>  obj-$(CONFIG_PPC_DOORBELL)	+= dbell.o
>  obj-$(CONFIG_JUMP_LABEL)	+= jump_label.o

Can we instead do:

obj-$(CONFIG_PPC_NOSPEC)	+= security.o

> diff --git a/arch/powerpc/kernel/security.c b/arch/powerpc/kernel/security.c
> index c55e102..797c975 100644
> --- a/arch/powerpc/kernel/security.c
> +++ b/arch/powerpc/kernel/security.c
> @@ -13,7 +13,9 @@
>  #include <asm/setup.h>
>  
>  
> +#ifdef CONFIG_PPC_BOOK3S_64
>  unsigned long powerpc_security_features __read_mostly = SEC_FTR_DEFAULT;
> +#endif /* CONFIG_PPC_BOOK3S_64 */

Why are you making that book3s specific?

By doing that you then can't use the existing versions of
setup_barrier_nospec() and cpu_show_spectre_v1/v2().

> @@ -24,6 +26,7 @@ static void enable_barrier_nospec(bool enable)
>  	do_barrier_nospec_fixups(enable);
>  }
>  
> +#ifdef CONFIG_PPC_BOOK3S_64
>  void setup_barrier_nospec(void)
>  {
>  	bool enable;
> @@ -46,6 +49,15 @@ void setup_barrier_nospec(void)
>  	if (!no_nospec)
>  		enable_barrier_nospec(enable);
>  }
> +#endif /* CONFIG_PPC_BOOK3S_64 */
> +
> +#ifdef CONFIG_PPC_FSL_BOOK3E
> +void setup_barrier_nospec(void)
> +{
> +	if (!no_nospec)
> +		enable_barrier_nospec(true);
> +}
> +#endif /* CONFIG_PPC_FSL_BOOK3E */

eg. that is identical to the existing version except for the feature check:

	enable = security_ftr_enabled(SEC_FTR_FAVOUR_SECURITY) &&
		 security_ftr_enabled(SEC_FTR_BNDS_CHK_SPEC_BAR);


Both those bits are enabled by default, so you shouldn't need to elide
that check.

So basically you should be able to use the existing
setup_barrier_nospec() if you just remove the ifdef around
powerpc_security_features. Or am I missing something?


> diff --git a/arch/powerpc/kernel/setup_32.c b/arch/powerpc/kernel/setup_32.c
> index 7445748..80c1e6e 100644
> --- a/arch/powerpc/kernel/setup_32.c
> +++ b/arch/powerpc/kernel/setup_32.c
> @@ -116,6 +116,11 @@ notrace void __init machine_init(u64 dt_ptr)
>  	/* Do some early initialization based on the flat device tree */
>  	early_init_devtree(__va(dt_ptr));
>  
> +	/* Apply the speculation barrier fixup */
> +#ifdef CONFIG_PPC_FSL_BOOK3E
> +	setup_barrier_nospec();
> +#endif

This ifdef should be handled in a header with an empty version for the
#else case.

> diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
> index 7a7ce8a..b2a644a 100644
> --- a/arch/powerpc/kernel/setup_64.c
> +++ b/arch/powerpc/kernel/setup_64.c
> @@ -327,6 +327,12 @@ void __init early_setup(unsigned long dt_ptr)
>  
>  	/* Apply all the dynamic patching */
>  	apply_feature_fixups();
> +
> +	/* Apply the speculation barrier fixup */
> +#ifdef CONFIG_PPC_FSL_BOOK3E
> +	setup_barrier_nospec();
> +#endif /* CONFIG_PPC_FSL_BOOK3E */

Can you call it from ppc_md->setup_arch() like the other platforms?

Failing that we could put it in setup_arch() after the call to
ppc_md->setup_arch(), so we can share it with powernv/pseries.

> diff --git a/arch/powerpc/lib/feature-fixups.c b/arch/powerpc/lib/feature-fixups.c
> index 2b9173d..bea2b87 100644
> --- a/arch/powerpc/lib/feature-fixups.c
> +++ b/arch/powerpc/lib/feature-fixups.c
> @@ -188,7 +188,40 @@ void do_barrier_nospec_fixups_range(bool enable, void *fixup_start, void *fixup_
>  
>  	printk(KERN_DEBUG "barrier-nospec: patched %d locations\n", i);
>  }
> +#endif /* CONFIG_PPC_BOOK3S_64 */
> +
> +#ifdef CONFIG_PPC_FSL_BOOK3E
> +void do_barrier_nospec_fixups_range(bool enable, void *fixup_start, void *fixup_end)
> +{
> +	unsigned int instr[2], *dest;
> +	long *start, *end;
> +	int i;
> +
> +	start = fixup_start;
> +	end = fixup_end;
> +
> +	instr[0] = PPC_INST_NOP;
> +	instr[1] = PPC_INST_NOP;
> +
> +	if (enable) {
> +		pr_info("barrier_nospec; using isync; sync as a speculation barrier\n");
> +		instr[0] = PPC_INST_ISYNC;
> +		instr[1] = PPC_INST_SYNC;
> +	}
> +
> +	for (i = 0; start < end; start++, i++) {
> +		dest = (void *)start + *start;
> +		pr_devel("patching dest %lx\n", (unsigned long)dest);
>  
> +		patch_instruction(dest, instr[0]);
> +		patch_instruction(dest + 1, instr[1]);
> +	}
> +
> +	pr_debug("barrier-nospec: patched %d locations\n", i);
> +}
> +#endif /* CONFIG_PPC_FSL_BOOK3E */

It's a bit unfortunate that we end up with two versions of that, which
are 80% the same. But merging them without ugly ifdefs would require a
bit more refactoring. So I guess it's OK for now.

cheers

Re: [PATCH v2 2/3] powerpc/fsl: Add barrier_nospec implementation for NXP PowerPC Book3E

[Diana Madalina Craciun]

Hi Michael,=0A=
=0A=
Thank you for the review.=0A=
=0A=
On 07/03/2018 10:26 AM, Michael Ellerman wrote:=0A=
> Hi Diana,=0A=
>=0A=
> A few comments below ...=0A=
>=0A=
> Diana Craciun <diana.craciun@nxp.com> writes:=0A=
>> Implement the barrier_nospec as a isync;sync instruction sequence.=0A=
>> The implementation uses the infrastructure built for BOOK3S 64.=0A=
> Do you have any details on why that sequence functions as an effective=0A=
> barrier on your chips?=0A=
=0A=
It was recommended by the hardware team, I do not have details.=0A=
=0A=
>=0A=
> In a lot of places we have eg:=0A=
>=0A=
>  +#if defined(CONFIG_PPC_BOOK3S_64) || defined(CONFIG_PPC_FSL_BOOK3E)=0A=
>=0A=
> Can you please add a Kconfig symbol to capture that. eg.=0A=
>=0A=
> config PPC_NOSPEC=0A=
> 	bool=0A=
>         default y=0A=
> 	depends on PPC_BOOK3S_64 || PPC_FSL_BOOK3E=0A=
>=0A=
>=0A=
> And then use that everywhere.=0A=
=0A=
OK.=0A=
=0A=
>=0A=
>> diff --git a/arch/powerpc/include/asm/barrier.h b/arch/powerpc/include/a=
sm/barrier.h=0A=
>> index f67b3f6..405d572 100644=0A=
>> --- a/arch/powerpc/include/asm/barrier.h=0A=
>> +++ b/arch/powerpc/include/asm/barrier.h=0A=
>> @@ -86,6 +86,16 @@ do {									\=0A=
>>  // This also acts as a compiler barrier due to the memory clobber.=0A=
>>  #define barrier_nospec() asm (stringify_in_c(barrier_nospec_asm) ::: "m=
emory")=0A=
>>  =0A=
>> +#elif defined(CONFIG_PPC_FSL_BOOK3E)=0A=
>> +/*=0A=
>> + * Prevent the execution of subsequent instructions speculatively using=
 a=0A=
>> + * isync;sync instruction sequence.=0A=
>> + */=0A=
>> +#define barrier_nospec_asm NOSPEC_BARRIER_FIXUP_SECTION; nop; nop=0A=
>> +=0A=
>> +// This also acts as a compiler barrier due to the memory clobber.=0A=
>> +#define barrier_nospec() asm (stringify_in_c(barrier_nospec_asm) ::: "m=
emory")=0A=
>> +=0A=
>>  #else /* !CONFIG_PPC_BOOK3S_64 */=0A=
>>  #define barrier_nospec_asm=0A=
>>  #define barrier_nospec()=0A=
> If we have CONFIG_PPC_NOSPEC this can be done something like:=0A=
>=0A=
> #ifdef CONFIG_PPC_BOOK3S_64=0A=
> #define NOSPEC_BARRIER_SLOT	nop=0A=
> #elif defined(CONFIG_PPC_FSL_BOOK3E)=0A=
> #define NOSPEC_BARRIER_SLOT	nop; nop=0A=
> #endif /* CONFIG_PPC_BOOK3S_64 */=0A=
>=0A=
> #ifdef CONFIG_PPC_NOSPEC=0A=
> /*=0A=
>  * Prevent execution of subsequent instructions until preceding branches =
have=0A=
>  * been fully resolved and are no longer executing speculatively.=0A=
>  */=0A=
> #define barrier_nospec_asm NOSPEC_BARRIER_FIXUP_SECTION; NOSPEC_BARRIER_S=
LOT=0A=
>=0A=
> // This also acts as a compiler barrier due to the memory clobber.=0A=
> #define barrier_nospec() asm (stringify_in_c(barrier_nospec_asm) ::: "mem=
ory")=0A=
> #else=0A=
> #define barrier_nospec_asm=0A=
> #define barrier_nospec()=0A=
> #endif /* CONFIG_PPC_NOSPEC */=0A=
=0A=
OK.=0A=
=0A=
>=0A=
>=0A=
>> diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile=
=0A=
>> index 2b4c40b2..d9dee43 100644=0A=
>> --- a/arch/powerpc/kernel/Makefile=0A=
>> +++ b/arch/powerpc/kernel/Makefile=0A=
>> @@ -76,7 +76,7 @@ endif=0A=
>>  obj64-$(CONFIG_HIBERNATION)	+=3D swsusp_asm64.o=0A=
>>  obj-$(CONFIG_MODULES)		+=3D module.o module_$(BITS).o=0A=
>>  obj-$(CONFIG_44x)		+=3D cpu_setup_44x.o=0A=
>> -obj-$(CONFIG_PPC_FSL_BOOK3E)	+=3D cpu_setup_fsl_booke.o=0A=
>> +obj-$(CONFIG_PPC_FSL_BOOK3E)	+=3D cpu_setup_fsl_booke.o security.o=0A=
>>  obj-$(CONFIG_PPC_DOORBELL)	+=3D dbell.o=0A=
>>  obj-$(CONFIG_JUMP_LABEL)	+=3D jump_label.o=0A=
> Can we instead do:=0A=
>=0A=
> obj-$(CONFIG_PPC_NOSPEC)	+=3D security.o=0A=
=0A=
OK=0A=
=0A=
>=0A=
>> diff --git a/arch/powerpc/kernel/security.c b/arch/powerpc/kernel/securi=
ty.c=0A=
>> index c55e102..797c975 100644=0A=
>> --- a/arch/powerpc/kernel/security.c=0A=
>> +++ b/arch/powerpc/kernel/security.c=0A=
>> @@ -13,7 +13,9 @@=0A=
>>  #include <asm/setup.h>=0A=
>>  =0A=
>>  =0A=
>> +#ifdef CONFIG_PPC_BOOK3S_64=0A=
>>  unsigned long powerpc_security_features __read_mostly =3D SEC_FTR_DEFAU=
LT;=0A=
>> +#endif /* CONFIG_PPC_BOOK3S_64 */=0A=
> Why are you making that book3s specific?=0A=
>=0A=
> By doing that you then can't use the existing versions of=0A=
> setup_barrier_nospec() and cpu_show_spectre_v1/v2().=0A=
>=0A=
>> @@ -24,6 +26,7 @@ static void enable_barrier_nospec(bool enable)=0A=
>>  	do_barrier_nospec_fixups(enable);=0A=
>>  }=0A=
>>  =0A=
>> +#ifdef CONFIG_PPC_BOOK3S_64=0A=
>>  void setup_barrier_nospec(void)=0A=
>>  {=0A=
>>  	bool enable;=0A=
>> @@ -46,6 +49,15 @@ void setup_barrier_nospec(void)=0A=
>>  	if (!no_nospec)=0A=
>>  		enable_barrier_nospec(enable);=0A=
>>  }=0A=
>> +#endif /* CONFIG_PPC_BOOK3S_64 */=0A=
>> +=0A=
>> +#ifdef CONFIG_PPC_FSL_BOOK3E=0A=
>> +void setup_barrier_nospec(void)=0A=
>> +{=0A=
>> +	if (!no_nospec)=0A=
>> +		enable_barrier_nospec(true);=0A=
>> +}=0A=
>> +#endif /* CONFIG_PPC_FSL_BOOK3E */=0A=
> eg. that is identical to the existing version except for the feature chec=
k:=0A=
>=0A=
> 	enable =3D security_ftr_enabled(SEC_FTR_FAVOUR_SECURITY) &&=0A=
> 		 security_ftr_enabled(SEC_FTR_BNDS_CHK_SPEC_BAR);=0A=
>=0A=
>=0A=
> Both those bits are enabled by default, so you shouldn't need to elide=0A=
> that check.=0A=
>=0A=
> So basically you should be able to use the existing=0A=
> setup_barrier_nospec() if you just remove the ifdef around=0A=
> powerpc_security_features. Or am I missing something?=0A=
=0A=
OK. I was under the impression that those bits are not enabled by=0A=
default. But obviously I was wrong. In this case I will use the existing=0A=
function.=0A=
=0A=
>=0A=
>=0A=
>> diff --git a/arch/powerpc/kernel/setup_32.c b/arch/powerpc/kernel/setup_=
32.c=0A=
>> index 7445748..80c1e6e 100644=0A=
>> --- a/arch/powerpc/kernel/setup_32.c=0A=
>> +++ b/arch/powerpc/kernel/setup_32.c=0A=
>> @@ -116,6 +116,11 @@ notrace void __init machine_init(u64 dt_ptr)=0A=
>>  	/* Do some early initialization based on the flat device tree */=0A=
>>  	early_init_devtree(__va(dt_ptr));=0A=
>>  =0A=
>> +	/* Apply the speculation barrier fixup */=0A=
>> +#ifdef CONFIG_PPC_FSL_BOOK3E=0A=
>> +	setup_barrier_nospec();=0A=
>> +#endif=0A=
> This ifdef should be handled in a header with an empty version for the=0A=
> #else case.=0A=
=0A=
OK=0A=
=0A=
>=0A=
>> diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_=
64.c=0A=
>> index 7a7ce8a..b2a644a 100644=0A=
>> --- a/arch/powerpc/kernel/setup_64.c=0A=
>> +++ b/arch/powerpc/kernel/setup_64.c=0A=
>> @@ -327,6 +327,12 @@ void __init early_setup(unsigned long dt_ptr)=0A=
>>  =0A=
>>  	/* Apply all the dynamic patching */=0A=
>>  	apply_feature_fixups();=0A=
>> +=0A=
>> +	/* Apply the speculation barrier fixup */=0A=
>> +#ifdef CONFIG_PPC_FSL_BOOK3E=0A=
>> +	setup_barrier_nospec();=0A=
>> +#endif /* CONFIG_PPC_FSL_BOOK3E */=0A=
> Can you call it from ppc_md->setup_arch() like the other platforms?=0A=
>=0A=
> Failing that we could put it in setup_arch() after the call to=0A=
> ppc_md->setup_arch(), so we can share it with powernv/pseries.=0A=
=0A=
The reason for which I did not call it from the ppc_md->setup_arch() was=0A=
that from my point of view the mitigation is not specific to the=0A=
platform code, but rather to the CPU.=0A=
=0A=
>=0A=
>> diff --git a/arch/powerpc/lib/feature-fixups.c b/arch/powerpc/lib/featur=
e-fixups.c=0A=
>> index 2b9173d..bea2b87 100644=0A=
>> --- a/arch/powerpc/lib/feature-fixups.c=0A=
>> +++ b/arch/powerpc/lib/feature-fixups.c=0A=
>> @@ -188,7 +188,40 @@ void do_barrier_nospec_fixups_range(bool enable, vo=
id *fixup_start, void *fixup_=0A=
>>  =0A=
>>  	printk(KERN_DEBUG "barrier-nospec: patched %d locations\n", i);=0A=
>>  }=0A=
>> +#endif /* CONFIG_PPC_BOOK3S_64 */=0A=
>> +=0A=
>> +#ifdef CONFIG_PPC_FSL_BOOK3E=0A=
>> +void do_barrier_nospec_fixups_range(bool enable, void *fixup_start, voi=
d *fixup_end)=0A=
>> +{=0A=
>> +	unsigned int instr[2], *dest;=0A=
>> +	long *start, *end;=0A=
>> +	int i;=0A=
>> +=0A=
>> +	start =3D fixup_start;=0A=
>> +	end =3D fixup_end;=0A=
>> +=0A=
>> +	instr[0] =3D PPC_INST_NOP;=0A=
>> +	instr[1] =3D PPC_INST_NOP;=0A=
>> +=0A=
>> +	if (enable) {=0A=
>> +		pr_info("barrier_nospec; using isync; sync as a speculation barrier\n=
");=0A=
>> +		instr[0] =3D PPC_INST_ISYNC;=0A=
>> +		instr[1] =3D PPC_INST_SYNC;=0A=
>> +	}=0A=
>> +=0A=
>> +	for (i =3D 0; start < end; start++, i++) {=0A=
>> +		dest =3D (void *)start + *start;=0A=
>> +		pr_devel("patching dest %lx\n", (unsigned long)dest);=0A=
>>  =0A=
>> +		patch_instruction(dest, instr[0]);=0A=
>> +		patch_instruction(dest + 1, instr[1]);=0A=
>> +	}=0A=
>> +=0A=
>> +	pr_debug("barrier-nospec: patched %d locations\n", i);=0A=
>> +}=0A=
>> +#endif /* CONFIG_PPC_FSL_BOOK3E */=0A=
> It's a bit unfortunate that we end up with two versions of that, which=0A=
> are 80% the same. But merging them without ugly ifdefs would require a=0A=
> bit more refactoring. So I guess it's OK for now.=0A=
>=0A=
> cheers=0A=
>=0A=
Regards,=0A=
=0A=
Diana=0A=
=0A=

Re: [PATCH v2 3/3] powerpc/fsl: Implement cpu_show_spectre_v1/v2 for NXP PowerPC Book3E

[Diana Madalina Craciun]

On 07/03/2018 10:26 AM, Michael Ellerman wrote:=0A=
> Michal Such=E1nek <msuchanek@suse.de> writes:=0A=
>> On Tue, 12 Jun 2018 02:59:11 +0000=0A=
>> Bharat Bhushan <bharat.bhushan@nxp.com> wrote:=0A=
>>=0A=
>>> Hi Diana,=0A=
>>>=0A=
>>>> -----Original Message-----=0A=
>>>> From: Diana Craciun [mailto:diana.craciun@nxp.com]=0A=
>>>> Sent: Monday, June 11, 2018 6:23 PM=0A=
>>>> To: linuxppc-dev@lists.ozlabs.org=0A=
>>>> Cc: mpe@ellerman.id.au; oss@buserror.net; Leo Li=0A=
>>>> <leoyang.li@nxp.com>; Bharat Bhushan <bharat.bhushan@nxp.com>;=0A=
>>>> Diana Madalina Craciun <diana.craciun@nxp.com>=0A=
>>>> Subject: [PATCH v2 3/3] powerpc/fsl: Implement=0A=
>>>> cpu_show_spectre_v1/v2 for NXP PowerPC Book3E  =0A=
>>> Please add some description=0A=
>> To me the subject is self-explanatory. It implements a kernel interface=
=0A=
>> that was already described elsewhere.=0A=
>>=0A=
>> What are you missing here?=0A=
> It should at least explain why it's reimplementing a function that=0A=
> already exists for powerpc. ie. Why can't the existing version be used?=
=0A=
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> cheers=0A=
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OK. I think I can use the cpu_show_spectre_v1 and for now I can use=0A=
cpu_show_spectre_v2 as well (the patches are under development for=0A=
mitigating Spectre v2). But I cannot use cpu_show_meltdown because it=0A=
uses references to variables that are specific to BOOK3S_64. But I do=0A=
not need a special implementation for cpu_show_meltdown because our=0A=
platform is not vulnerable to Meltdown. So, I will just ifdef the=0A=
cpu_show_meltdown and leave the default implementation.=0A=
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Diana=0A=
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