[PATCH v2] ppc: use rfid when running under a CPU from the 970 family.

[Cédric Le Goater]

A recent attempt to restrict the use of rfi on 64bit cpus in qemu
broke 32bit OpenBIOS when run under a 970.

This patches memory to replace rfi instructions with rfid in the
vector code.

Signed-off-by: Cédric Le Goater <clg(a)kaod.org>
Suggested-by: Alexander Graf <agraf(a)suse.de>
---

 Tested on qemu.

 arch/ppc/qemu/ofmem.c |   24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

Index: openbios.git/arch/ppc/qemu/ofmem.c
===================================================================
--- openbios.git.orig/arch/ppc/qemu/ofmem.c
+++ openbios.git/arch/ppc/qemu/ofmem.c
@@ -478,6 +478,26 @@ isi_exception(void)
     hash_page(nip, phys, mode);
 }
 
+/* When running on ppc64, we cannot use rfi anymore. Let's patch the
+ * vectors to use rfid instead.
+ */
+#define RFI     0x4c000064
+#define RFID    0x4c000024
+
+static void patch_rfi(char *from, uint32_t len)
+{
+    int i;
+
+    for (i = 0; i < len; i += 4)  {
+        uint32_t* addr = (uint32_t *) (from + i);
+        if (*addr == RFI)
+            *addr = RFID;
+    }
+    flush_icache_range(from, from + len);
+}
+
+extern char __vectors[];
+extern char __vectors_end[];
 
 /************************************************************************/
 /*	init / cleanup							*/
@@ -532,6 +552,10 @@ setup_mmu(unsigned long ramsize)
 
     memcpy((void *)get_rom_base(), (void *)OF_CODE_START, OF_CODE_SIZE);
 
+    if (is_ppc64()) {
+        patch_rfi(0x0, (uint32_t) __vectors_end - (uint32_t) __vectors);
+    }
+
     /* Enable MMU */
 
     mtmsr(mfmsr() | MSR_IR | MSR_DR);

[Alexander Graf]

  Am 21.06.2016 um 23:36 schrieb Cédric Le Goater
<clg(a)kaod.org>rg>:
 
 A recent attempt to restrict the use of rfi on 64bit cpus in qemu
 broke 32bit OpenBIOS when run under a 970.
 
 This patches memory to replace rfi instructions with rfid in the
 vector code.
 
 Signed-off-by: Cédric Le Goater <clg(a)kaod.org>
 Suggested-by: Alexander Graf <agraf(a)suse.de>
 ---
 
 Tested on qemu.
 
 arch/ppc/qemu/ofmem.c |   24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)
 
 Index: openbios.git/arch/ppc/qemu/ofmem.c
 ===================================================================
 --- openbios.git.orig/arch/ppc/qemu/ofmem.c
 +++ openbios.git/arch/ppc/qemu/ofmem.c
 @@ -478,6 +478,26 @@ isi_exception(void)
     hash_page(nip, phys, mode);
 }
 
 +/* When running on ppc64, we cannot use rfi anymore. Let's patch the
 + * vectors to use rfid instead.
 + */
 +#define RFI     0x4c000064
 +#define RFID    0x4c000024
 +
 +static void patch_rfi(char *from, uint32_t len)
 +{
 +    int i;
 +
 +    for (i = 0; i < len; i += 4)  {
 +        uint32_t* addr = (uint32_t *) (from + i);
If you use a uint32* here you can just increment by 1 ...

  +        if (*addr == RFI)
 +            *addr = RFID;
 +    }
 +    flush_icache_range(from, from + len);
 +}
 +
 +extern char __vectors[];
 +extern char __vectors_end[];
And in fact you can just loop from vectors until ptr==vectors_end.

uint32_t *ptr;

for (ptr = __vectors; ptr != __vectors_end; ptr++)

  
 /************************************************************************/
 /*    init / cleanup                            */
 @@ -532,6 +552,10 @@ setup_mmu(unsigned long ramsize)
 
     memcpy((void *)get_rom_base(), (void *)OF_CODE_START, OF_CODE_SIZE);
 
 +    if (is_ppc64()) {
 +        patch_rfi(0x0, (uint32_t) __vectors_end - (uint32_t) __vectors);
 +    }
Just fold all of this together. Make patch_rfi have no parameters and just call it
unconditionally. Then check for ppc64 in there.

Alex

  +
     /* Enable MMU */
 
     mtmsr(mfmsr() | MSR_IR | MSR_DR);

[Cédric Le Goater]

On 06/22/2016 06:50 AM, Alexander Graf wrote:
  
 
  Am 21.06.2016 um 23:36 schrieb Cédric Le Goater
<clg(a)kaod.org>rg>:

 A recent attempt to restrict the use of rfi on 64bit cpus in qemu
 broke 32bit OpenBIOS when run under a 970.

 This patches memory to replace rfi instructions with rfid in the
 vector code.

 Signed-off-by: Cédric Le Goater <clg(a)kaod.org>
 Suggested-by: Alexander Graf <agraf(a)suse.de>
 ---

 Tested on qemu.

 arch/ppc/qemu/ofmem.c |   24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

 Index: openbios.git/arch/ppc/qemu/ofmem.c
 ===================================================================
 --- openbios.git.orig/arch/ppc/qemu/ofmem.c
 +++ openbios.git/arch/ppc/qemu/ofmem.c
 @@ -478,6 +478,26 @@ isi_exception(void)
     hash_page(nip, phys, mode);
 }

 +/* When running on ppc64, we cannot use rfi anymore. Let's patch the
 + * vectors to use rfid instead.
 + */
 +#define RFI     0x4c000064
 +#define RFID    0x4c000024
 +
 +static void patch_rfi(char *from, uint32_t len)
 +{
 +    int i;
 +
 +    for (i = 0; i < len; i += 4)  {
 +        uint32_t* addr = (uint32_t *) (from + i);
 
 If you use a uint32* here you can just increment by 1 ...
yes. I tried a couple of versions and that was the most friendly for the
flush_icache_range.

 
  +        if
(*addr == RFI)
 +            *addr = RFID;
 +    }
 +    flush_icache_range(from, from + len);
 +}
 +
 +extern char __vectors[];
 +extern char __vectors_end[];
 
 And in fact you can just loop from vectors until ptr==vectors_end.
 
 uint32_t *ptr;
 
 for (ptr = __vectors; ptr != __vectors_end; ptr++)
 
 
 /************************************************************************/
 /*    init / cleanup                            */
 @@ -532,6 +552,10 @@ setup_mmu(unsigned long ramsize)

     memcpy((void *)get_rom_base(), (void *)OF_CODE_START, OF_CODE_SIZE);

 +    if (is_ppc64()) {
 +        patch_rfi(0x0, (uint32_t) __vectors_end - (uint32_t) __vectors);
 +    }
 
 Just fold all of this together. Make patch_rfi have no parameters and just call it
unconditionally. Then check for ppc64 in there.
ok. v3 on the way.

Thanks, 

C. 

  Alex
 
  +
     /* Enable MMU */

     mtmsr(mfmsr() | MSR_IR | MSR_DR);

[Alexander Graf]

  Am 22.06.2016 um 08:42 schrieb Cédric Le Goater
<clg(a)kaod.org>rg>:
 
  On 06/22/2016 06:50 AM, Alexander Graf wrote:
 
 
  Am 21.06.2016 um 23:36 schrieb Cédric Le Goater
<clg(a)kaod.org>rg>:
 
 A recent attempt to restrict the use of rfi on 64bit cpus in qemu
 broke 32bit OpenBIOS when run under a 970.
 
 This patches memory to replace rfi instructions with rfid in the
 vector code.
 
 Signed-off-by: Cédric Le Goater <clg(a)kaod.org>
 Suggested-by: Alexander Graf <agraf(a)suse.de>
 ---
 
 Tested on qemu.
 
 arch/ppc/qemu/ofmem.c |   24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)
 
 Index: openbios.git/arch/ppc/qemu/ofmem.c
 ===================================================================
 --- openbios.git.orig/arch/ppc/qemu/ofmem.c
 +++ openbios.git/arch/ppc/qemu/ofmem.c
 @@ -478,6 +478,26 @@ isi_exception(void)
    hash_page(nip, phys, mode);
 }
 
 +/* When running on ppc64, we cannot use rfi anymore. Let's patch the
 + * vectors to use rfid instead.
 + */
 +#define RFI     0x4c000064
 +#define RFID    0x4c000024
 +
 +static void patch_rfi(char *from, uint32_t len)
 +{
 +    int i;
 +
 +    for (i = 0; i < len; i += 4)  {
 +        uint32_t* addr = (uint32_t *) (from + i);
 
 If you use a uint32* here you can just increment by 1 ...
 
 yes. I tried a couple of versions and that was the most friendly for the
 flush_icache_range.
Just call it for every instruction :)

Alex

  
 
  +       
if (*addr == RFI)
 +            *addr = RFID;
 +    }
 +    flush_icache_range(from, from + len);
 +}
 +
 +extern char __vectors[];
 +extern char __vectors_end[];
 
 And in fact you can just loop from vectors until ptr==vectors_end.
 
 uint32_t *ptr;
 
 for (ptr = __vectors; ptr != __vectors_end; ptr++)
 
  
 /************************************************************************/
 /*    init / cleanup                            */
 @@ -532,6 +552,10 @@ setup_mmu(unsigned long ramsize)
 
    memcpy((void *)get_rom_base(), (void *)OF_CODE_START, OF_CODE_SIZE);
 
 +    if (is_ppc64()) {
 +        patch_rfi(0x0, (uint32_t) __vectors_end - (uint32_t) __vectors);
 +    }
 
 Just fold all of this together. Make patch_rfi have no parameters and just call it
unconditionally. Then check for ppc64 in there.
 
 ok. v3 on the way.
 
 Thanks, 
 
 C. 
 
  Alex
 
> +
>    /* Enable MMU */
> 
>    mtmsr(mfmsr() | MSR_IR | MSR_DR);

[Cédric Le Goater]

On 06/22/2016 06:50 AM, Alexander Graf wrote:
  
 
  Am 21.06.2016 um 23:36 schrieb Cédric Le Goater
<clg(a)kaod.org>rg>:

 A recent attempt to restrict the use of rfi on 64bit cpus in qemu
 broke 32bit OpenBIOS when run under a 970.

 This patches memory to replace rfi instructions with rfid in the
 vector code.

 Signed-off-by: Cédric Le Goater <clg(a)kaod.org>
 Suggested-by: Alexander Graf <agraf(a)suse.de>
 ---

 Tested on qemu.

 arch/ppc/qemu/ofmem.c |   24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

 Index: openbios.git/arch/ppc/qemu/ofmem.c
 ===================================================================
 --- openbios.git.orig/arch/ppc/qemu/ofmem.c
 +++ openbios.git/arch/ppc/qemu/ofmem.c
 @@ -478,6 +478,26 @@ isi_exception(void)
     hash_page(nip, phys, mode);
 }

 +/* When running on ppc64, we cannot use rfi anymore. Let's patch the
 + * vectors to use rfid instead.
 + */
 +#define RFI     0x4c000064
 +#define RFID    0x4c000024
 +
 +static void patch_rfi(char *from, uint32_t len)
 +{
 +    int i;
 +
 +    for (i = 0; i < len; i += 4)  {
 +        uint32_t* addr = (uint32_t *) (from + i);
 
 If you use a uint32* here you can just increment by 1 ...
 
  +        if (*addr == RFI)
 +            *addr = RFID;
 +    }
 +    flush_icache_range(from, from + len);
 +}
 +
 +extern char __vectors[];
 +extern char __vectors_end[];
 
 And in fact you can just loop from vectors until ptr==vectors_end.
 
 uint32_t *ptr;
 
 for (ptr = __vectors; ptr != __vectors_end; ptr++)
ah, we can not do that, we need to patch the memory and not the rom, so 
[ 0,  __vectors_end - __vectors]

C. 

  
 
 /************************************************************************/
 /*    init / cleanup                            */
 @@ -532,6 +552,10 @@ setup_mmu(unsigned long ramsize)

     memcpy((void *)get_rom_base(), (void *)OF_CODE_START, OF_CODE_SIZE);

 +    if (is_ppc64()) {
 +        patch_rfi(0x0, (uint32_t) __vectors_end - (uint32_t) __vectors);
 +    }
 
 Just fold all of this together. Make patch_rfi have no parameters and just call it
unconditionally. Then check for ppc64 in there.
 
 Alex
 
  +
     /* Enable MMU */

     mtmsr(mfmsr() | MSR_IR | MSR_DR);

[Alexander Graf]

  Am 22.06.2016 um 09:08 schrieb Cédric Le Goater
<clg(a)kaod.org>rg>:
 
  On 06/22/2016 06:50 AM, Alexander Graf wrote:
 
 
  Am 21.06.2016 um 23:36 schrieb Cédric Le Goater
<clg(a)kaod.org>rg>:
 
 A recent attempt to restrict the use of rfi on 64bit cpus in qemu
 broke 32bit OpenBIOS when run under a 970.
 
 This patches memory to replace rfi instructions with rfid in the
 vector code.
 
 Signed-off-by: Cédric Le Goater <clg(a)kaod.org>
 Suggested-by: Alexander Graf <agraf(a)suse.de>
 ---
 
 Tested on qemu.
 
 arch/ppc/qemu/ofmem.c |   24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)
 
 Index: openbios.git/arch/ppc/qemu/ofmem.c
 ===================================================================
 --- openbios.git.orig/arch/ppc/qemu/ofmem.c
 +++ openbios.git/arch/ppc/qemu/ofmem.c
 @@ -478,6 +478,26 @@ isi_exception(void)
    hash_page(nip, phys, mode);
 }
 
 +/* When running on ppc64, we cannot use rfi anymore. Let's patch the
 + * vectors to use rfid instead.
 + */
 +#define RFI     0x4c000064
 +#define RFID    0x4c000024
 +
 +static void patch_rfi(char *from, uint32_t len)
 +{
 +    int i;
 +
 +    for (i = 0; i < len; i += 4)  {
 +        uint32_t* addr = (uint32_t *) (from + i);
 
 If you use a uint32* here you can just increment by 1 ...
 
  +        if (*addr == RFI)
 +            *addr = RFID;
 +    }
 +    flush_icache_range(from, from + len);
 +}
 +
 +extern char __vectors[];
 +extern char __vectors_end[];
 
 And in fact you can just loop from vectors until ptr==vectors_end.
 
 uint32_t *ptr;
 
 for (ptr = __vectors; ptr != __vectors_end; ptr++)
 
 ah, we can not do that, we need to patch the memory and not the rom, so 
 [ 0,  __vectors_end - __vectors]
Aaah, I see. Then your version makes more sense.

  
 C. 
 
> 
>> 
>> /************************************************************************/
>> /*    init / cleanup                            */
>> @@ -532,6 +552,10 @@ setup_mmu(unsigned long ramsize)
>> 
>>    memcpy((void *)get_rom_base(), (void *)OF_CODE_START, OF_CODE_SIZE);
>> 
>> +    if (is_ppc64()) {
>> +        patch_rfi(0x0, (uint32_t) __vectors_end - (uint32_t) __vectors);
Please cast to uintptr_t instead though :)

Alex

  +    }
 
 Just fold all of this together. Make patch_rfi have no parameters and just call it
unconditionally. Then check for ppc64 in there.
 
 Alex
 
> +
>    /* Enable MMU */
> 
>    mtmsr(mfmsr() | MSR_IR | MSR_DR);