[2/2] powerpc/powernv: Wire up OPAL address lookups
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Message ID 20200228031027.271510-2-npiggin@gmail.com
State Not Applicable
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  • [1/2] kallsyms: architecture specific symbol lookups
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Commit Message

Nicholas Piggin Feb. 28, 2020, 3:10 a.m. UTC
Use ARCH_HAS_ADDRESS_LOOKUP to look up the opal symbol table. This
allows crashes and xmon debugging to print firmware symbols.

  Oops: System Reset, sig: 6 [#1]
  LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=2048 NUMA PowerNV
  Modules linked in:
  CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.6.0-rc2-dirty #903
  NIP:  0000000030020434 LR: 000000003000378c CTR: 0000000030020414
  REGS: c0000000fffc3d70 TRAP: 0100   Not tainted  (5.6.0-rc2-dirty)
  MSR:  9000000002101002 <SF,HV,VEC,ME,RI>  CR: 28022284  XER: 20040000
  CFAR: 0000000030003788 IRQMASK: 3
  GPR00: 000000003000378c 0000000031c13c90 0000000030136200 c0000000012cfa10
  GPR04: c0000000012cfa10 0000000000000010 0000000000000000 0000000031c10060
  GPR08: c0000000012cfaaf 0000000030003640 0000000000000000 0000000000000001
  GPR12: 00000000300e0000 c000000001490000 0000000000000000 c00000000139c588
  GPR16: 0000000031c10000 c00000000125a900 0000000000000000 c0000000012076a8
  GPR20: c0000000012a3950 0000000000000001 0000000031c10060 c0000000012cfaaf
  GPR24: 0000000000000019 0000000030003640 0000000000000000 0000000000000000
  GPR28: 0000000000000010 c0000000012cfa10 0000000000000000 0000000000000000
  NIP [0000000030020434] .dummy_console_write_buffer_space+0x20/0x64 [OPAL]
  LR [000000003000378c] opal_entry+0x14c/0x17c [OPAL]

This won't unwind the firmware stack (or its Linux caller) properly if
firmware and kernel endians don't match, but that problem could be solved
in powerpc's unwinder.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 arch/powerpc/Kconfig                       |  1 +
 arch/powerpc/include/asm/opal-api.h        |  6 +++-
 arch/powerpc/include/asm/opal.h            |  3 ++
 arch/powerpc/platforms/powernv/opal-call.c |  2 ++
 arch/powerpc/platforms/powernv/opal.c      | 40 ++++++++++++++++++++++
 5 files changed, 51 insertions(+), 1 deletion(-)

Comments

Michael Ellerman March 3, 2020, 11:43 a.m. UTC | #1
Nicholas Piggin <npiggin@gmail.com> writes:
> Use ARCH_HAS_ADDRESS_LOOKUP to look up the opal symbol table. This
> allows crashes and xmon debugging to print firmware symbols.
>
>   Oops: System Reset, sig: 6 [#1]
>   LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=2048 NUMA PowerNV
>   Modules linked in:
>   CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.6.0-rc2-dirty #903
>   NIP:  0000000030020434 LR: 000000003000378c CTR: 0000000030020414
>   REGS: c0000000fffc3d70 TRAP: 0100   Not tainted  (5.6.0-rc2-dirty)
>   MSR:  9000000002101002 <SF,HV,VEC,ME,RI>  CR: 28022284  XER: 20040000
>   CFAR: 0000000030003788 IRQMASK: 3
>   GPR00: 000000003000378c 0000000031c13c90 0000000030136200 c0000000012cfa10
>   GPR04: c0000000012cfa10 0000000000000010 0000000000000000 0000000031c10060
>   GPR08: c0000000012cfaaf 0000000030003640 0000000000000000 0000000000000001
>   GPR12: 00000000300e0000 c000000001490000 0000000000000000 c00000000139c588
>   GPR16: 0000000031c10000 c00000000125a900 0000000000000000 c0000000012076a8
>   GPR20: c0000000012a3950 0000000000000001 0000000031c10060 c0000000012cfaaf
>   GPR24: 0000000000000019 0000000030003640 0000000000000000 0000000000000000
>   GPR28: 0000000000000010 c0000000012cfa10 0000000000000000 0000000000000000
>   NIP [0000000030020434] .dummy_console_write_buffer_space+0x20/0x64 [OPAL]
>   LR [000000003000378c] opal_entry+0x14c/0x17c [OPAL]
>
> This won't unwind the firmware stack (or its Linux caller) properly if
> firmware and kernel endians don't match, but that problem could be solved
> in powerpc's unwinder.

How well does this work if we're tracing opal calls at the time we oops :)

Though it looks like that's already fishy because we don't do anything
to disable tracing of opal_console_write().

I guess I'm a bit wary of adding numerous further opal calls in the oops
path, I'm sure the opal symbol lookup code is bug free, but still.

Could we instead suck in the opal symbols early on, and search them in
Linux? I suspect you've thought of that and rejected it, but it would be
good to document why.

cheers

> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index 497b7d0b2d7e..4d32b02d35e8 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -115,6 +115,7 @@ config PPC
>  	# Please keep this list sorted alphabetically.
>  	#
>  	select ARCH_32BIT_OFF_T if PPC32
> +	select ARCH_HAS_ADDRESS_LOOKUP		if PPC_POWERNV
>  	select ARCH_HAS_DEBUG_VIRTUAL
>  	select ARCH_HAS_DEVMEM_IS_ALLOWED
>  	select ARCH_HAS_ELF_RANDOMIZE
> diff --git a/arch/powerpc/include/asm/opal-api.h b/arch/powerpc/include/asm/opal-api.h
> index c1f25a760eb1..c3a2a797177a 100644
> --- a/arch/powerpc/include/asm/opal-api.h
> +++ b/arch/powerpc/include/asm/opal-api.h
> @@ -214,7 +214,11 @@
>  #define OPAL_SECVAR_GET				176
>  #define OPAL_SECVAR_GET_NEXT			177
>  #define OPAL_SECVAR_ENQUEUE_UPDATE		178
> -#define OPAL_LAST				178
> +#define OPAL_PHB_SET_OPTION			179
> +#define OPAL_PHB_GET_OPTION			180

Only pull in the calls you need for this patch.

> +#define OPAL_GET_SYMBOL				181
> +#define OPAL_LOOKUP_SYMBOL			182
> +#define OPAL_LAST				182
>  
>  #define QUIESCE_HOLD			1 /* Spin all calls at entry */
>  #define QUIESCE_REJECT			2 /* Fail all calls with OPAL_BUSY */
> diff --git a/arch/powerpc/include/asm/opal.h b/arch/powerpc/include/asm/opal.h
> index 9986ac34b8e2..ef2d9273f06f 100644
> --- a/arch/powerpc/include/asm/opal.h
> +++ b/arch/powerpc/include/asm/opal.h
> @@ -312,6 +312,9 @@ s64 opal_mpipl_query_tag(enum opal_mpipl_tags tag, u64 *addr);
>  s64 opal_signal_system_reset(s32 cpu);
>  s64 opal_quiesce(u64 shutdown_type, s32 cpu);
>  
> +int64_t opal_get_symbol(uint64_t addr, __be64 *symaddr, __be64 *symsize, char *namebuf, uint64_t buflen);
> +int64_t opal_lookup_symbol(const char *name, __be64 *symaddr, __be64 *symsize);
> +
>  /* Internal functions */
>  extern int early_init_dt_scan_opal(unsigned long node, const char *uname,
>  				   int depth, void *data);
> diff --git a/arch/powerpc/platforms/powernv/opal-call.c b/arch/powerpc/platforms/powernv/opal-call.c
> index 5cd0f52d258f..ba11112d94df 100644
> --- a/arch/powerpc/platforms/powernv/opal-call.c
> +++ b/arch/powerpc/platforms/powernv/opal-call.c
> @@ -293,3 +293,5 @@ OPAL_CALL(opal_mpipl_query_tag,			OPAL_MPIPL_QUERY_TAG);
>  OPAL_CALL(opal_secvar_get,			OPAL_SECVAR_GET);
>  OPAL_CALL(opal_secvar_get_next,			OPAL_SECVAR_GET_NEXT);
>  OPAL_CALL(opal_secvar_enqueue_update,		OPAL_SECVAR_ENQUEUE_UPDATE);
> +OPAL_CALL(opal_get_symbol,			OPAL_GET_SYMBOL);
> +OPAL_CALL(opal_lookup_symbol,			OPAL_LOOKUP_SYMBOL);
> diff --git a/arch/powerpc/platforms/powernv/opal.c b/arch/powerpc/platforms/powernv/opal.c
> index 2b3dfd0b6cdd..fdf6c4e6f7f9 100644
> --- a/arch/powerpc/platforms/powernv/opal.c
> +++ b/arch/powerpc/platforms/powernv/opal.c
> @@ -107,6 +107,46 @@ void opal_configure_cores(void)
>  		cur_cpu_spec->cpu_restore();
>  }
>  
> +const char *arch_address_lookup(unsigned long addr,
> +			    unsigned long *symbolsize,
> +			    unsigned long *offset,
> +			    char **modname, char *namebuf)
> +{
> +	__be64 symaddr;
> +	__be64 symsize;
> +
> +	if (!firmware_has_feature(FW_FEATURE_OPAL))
> +		return NULL;
> +
> +	if (opal_get_symbol(addr, &symaddr, &symsize, namebuf,
> +			cpu_to_be64(KSYM_NAME_LEN)) != OPAL_SUCCESS)
> +		return NULL;
> +
> +	*symbolsize = be64_to_cpu(symsize);
> +	*offset = addr - be64_to_cpu(symaddr);
> +	*modname = "OPAL";
> +
> +	return namebuf;
> +}
> +
> +unsigned long arch_address_lookup_name(const char *name)
> +{
> +	__be64 addr;
> +	__be64 size;
> +
> +	if (!firmware_has_feature(FW_FEATURE_OPAL))
> +		return 0;
> +
> +	/* opal: prefix allows lookup of symbols that clash with kernel */
> +	if (!strncasecmp(name, "opal:", strlen("opal:")))
> +		name += strlen("opal:");
> +
> +	if (opal_lookup_symbol(name, &addr, &size) != OPAL_SUCCESS)
> +		return 0;
> +
> +	return be64_to_cpu(addr);
> +}
> +
>  int __init early_init_dt_scan_opal(unsigned long node,
>  				   const char *uname, int depth, void *data)
>  {
> -- 
> 2.23.0
Nicholas Piggin March 5, 2020, 3:43 a.m. UTC | #2
Michael Ellerman's on March 3, 2020 9:43 pm:
> Nicholas Piggin <npiggin@gmail.com> writes:
>> Use ARCH_HAS_ADDRESS_LOOKUP to look up the opal symbol table. This
>> allows crashes and xmon debugging to print firmware symbols.
>>
>>   Oops: System Reset, sig: 6 [#1]
>>   LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=2048 NUMA PowerNV
>>   Modules linked in:
>>   CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.6.0-rc2-dirty #903
>>   NIP:  0000000030020434 LR: 000000003000378c CTR: 0000000030020414
>>   REGS: c0000000fffc3d70 TRAP: 0100   Not tainted  (5.6.0-rc2-dirty)
>>   MSR:  9000000002101002 <SF,HV,VEC,ME,RI>  CR: 28022284  XER: 20040000
>>   CFAR: 0000000030003788 IRQMASK: 3
>>   GPR00: 000000003000378c 0000000031c13c90 0000000030136200 c0000000012cfa10
>>   GPR04: c0000000012cfa10 0000000000000010 0000000000000000 0000000031c10060
>>   GPR08: c0000000012cfaaf 0000000030003640 0000000000000000 0000000000000001
>>   GPR12: 00000000300e0000 c000000001490000 0000000000000000 c00000000139c588
>>   GPR16: 0000000031c10000 c00000000125a900 0000000000000000 c0000000012076a8
>>   GPR20: c0000000012a3950 0000000000000001 0000000031c10060 c0000000012cfaaf
>>   GPR24: 0000000000000019 0000000030003640 0000000000000000 0000000000000000
>>   GPR28: 0000000000000010 c0000000012cfa10 0000000000000000 0000000000000000
>>   NIP [0000000030020434] .dummy_console_write_buffer_space+0x20/0x64 [OPAL]
>>   LR [000000003000378c] opal_entry+0x14c/0x17c [OPAL]
>>
>> This won't unwind the firmware stack (or its Linux caller) properly if
>> firmware and kernel endians don't match, but that problem could be solved
>> in powerpc's unwinder.
> 
> How well does this work if we're tracing opal calls at the time we oops :)
> 
> Though it looks like that's already fishy because we don't do anything
> to disable tracing of opal_console_write().

Yeah we don't do perfectly well in this case still. OPAL itself has
locks in its console paths and some issues with stack reentrancy.
We should do a bit better with cutting out more junk including tracing
from crash paths, so this doesn't fundamentally make things harder.

> I guess I'm a bit wary of adding numerous further opal calls in the oops
> path, I'm sure the opal symbol lookup code is bug free, but still.

There's a few, console write, event poll, reboot, and NMI IPI AFAIK,
so we have to make the opal call path itself robust (it's getting
there).

> Could we instead suck in the opal symbols early on, and search them in
> Linux? I suspect you've thought of that and rejected it, but it would be
> good to document why.

We could, I was thinking we might want OPAL to do something special
with them like add module annotations [OPAL] vs [HOMER] or whatever,
relocate itself after boot if we randomize where it's loaded etc.
but perhaps none of those things really prevent the symbols being
discovered at boot time. I don't know, it was easier? :)

>> diff --git a/arch/powerpc/include/asm/opal-api.h b/arch/powerpc/include/asm/opal-api.h
>> index c1f25a760eb1..c3a2a797177a 100644
>> --- a/arch/powerpc/include/asm/opal-api.h
>> +++ b/arch/powerpc/include/asm/opal-api.h
>> @@ -214,7 +214,11 @@
>>  #define OPAL_SECVAR_GET				176
>>  #define OPAL_SECVAR_GET_NEXT			177
>>  #define OPAL_SECVAR_ENQUEUE_UPDATE		178
>> -#define OPAL_LAST				178
>> +#define OPAL_PHB_SET_OPTION			179
>> +#define OPAL_PHB_GET_OPTION			180
> 
> Only pull in the calls you need for this patch.

Ah okay I didn't realise that was the policy, makes sense.

Thanks,
Nick

Patch
diff mbox series

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 497b7d0b2d7e..4d32b02d35e8 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -115,6 +115,7 @@  config PPC
 	# Please keep this list sorted alphabetically.
 	#
 	select ARCH_32BIT_OFF_T if PPC32
+	select ARCH_HAS_ADDRESS_LOOKUP		if PPC_POWERNV
 	select ARCH_HAS_DEBUG_VIRTUAL
 	select ARCH_HAS_DEVMEM_IS_ALLOWED
 	select ARCH_HAS_ELF_RANDOMIZE
diff --git a/arch/powerpc/include/asm/opal-api.h b/arch/powerpc/include/asm/opal-api.h
index c1f25a760eb1..c3a2a797177a 100644
--- a/arch/powerpc/include/asm/opal-api.h
+++ b/arch/powerpc/include/asm/opal-api.h
@@ -214,7 +214,11 @@ 
 #define OPAL_SECVAR_GET				176
 #define OPAL_SECVAR_GET_NEXT			177
 #define OPAL_SECVAR_ENQUEUE_UPDATE		178
-#define OPAL_LAST				178
+#define OPAL_PHB_SET_OPTION			179
+#define OPAL_PHB_GET_OPTION			180
+#define OPAL_GET_SYMBOL				181
+#define OPAL_LOOKUP_SYMBOL			182
+#define OPAL_LAST				182
 
 #define QUIESCE_HOLD			1 /* Spin all calls at entry */
 #define QUIESCE_REJECT			2 /* Fail all calls with OPAL_BUSY */
diff --git a/arch/powerpc/include/asm/opal.h b/arch/powerpc/include/asm/opal.h
index 9986ac34b8e2..ef2d9273f06f 100644
--- a/arch/powerpc/include/asm/opal.h
+++ b/arch/powerpc/include/asm/opal.h
@@ -312,6 +312,9 @@  s64 opal_mpipl_query_tag(enum opal_mpipl_tags tag, u64 *addr);
 s64 opal_signal_system_reset(s32 cpu);
 s64 opal_quiesce(u64 shutdown_type, s32 cpu);
 
+int64_t opal_get_symbol(uint64_t addr, __be64 *symaddr, __be64 *symsize, char *namebuf, uint64_t buflen);
+int64_t opal_lookup_symbol(const char *name, __be64 *symaddr, __be64 *symsize);
+
 /* Internal functions */
 extern int early_init_dt_scan_opal(unsigned long node, const char *uname,
 				   int depth, void *data);
diff --git a/arch/powerpc/platforms/powernv/opal-call.c b/arch/powerpc/platforms/powernv/opal-call.c
index 5cd0f52d258f..ba11112d94df 100644
--- a/arch/powerpc/platforms/powernv/opal-call.c
+++ b/arch/powerpc/platforms/powernv/opal-call.c
@@ -293,3 +293,5 @@  OPAL_CALL(opal_mpipl_query_tag,			OPAL_MPIPL_QUERY_TAG);
 OPAL_CALL(opal_secvar_get,			OPAL_SECVAR_GET);
 OPAL_CALL(opal_secvar_get_next,			OPAL_SECVAR_GET_NEXT);
 OPAL_CALL(opal_secvar_enqueue_update,		OPAL_SECVAR_ENQUEUE_UPDATE);
+OPAL_CALL(opal_get_symbol,			OPAL_GET_SYMBOL);
+OPAL_CALL(opal_lookup_symbol,			OPAL_LOOKUP_SYMBOL);
diff --git a/arch/powerpc/platforms/powernv/opal.c b/arch/powerpc/platforms/powernv/opal.c
index 2b3dfd0b6cdd..fdf6c4e6f7f9 100644
--- a/arch/powerpc/platforms/powernv/opal.c
+++ b/arch/powerpc/platforms/powernv/opal.c
@@ -107,6 +107,46 @@  void opal_configure_cores(void)
 		cur_cpu_spec->cpu_restore();
 }
 
+const char *arch_address_lookup(unsigned long addr,
+			    unsigned long *symbolsize,
+			    unsigned long *offset,
+			    char **modname, char *namebuf)
+{
+	__be64 symaddr;
+	__be64 symsize;
+
+	if (!firmware_has_feature(FW_FEATURE_OPAL))
+		return NULL;
+
+	if (opal_get_symbol(addr, &symaddr, &symsize, namebuf,
+			cpu_to_be64(KSYM_NAME_LEN)) != OPAL_SUCCESS)
+		return NULL;
+
+	*symbolsize = be64_to_cpu(symsize);
+	*offset = addr - be64_to_cpu(symaddr);
+	*modname = "OPAL";
+
+	return namebuf;
+}
+
+unsigned long arch_address_lookup_name(const char *name)
+{
+	__be64 addr;
+	__be64 size;
+
+	if (!firmware_has_feature(FW_FEATURE_OPAL))
+		return 0;
+
+	/* opal: prefix allows lookup of symbols that clash with kernel */
+	if (!strncasecmp(name, "opal:", strlen("opal:")))
+		name += strlen("opal:");
+
+	if (opal_lookup_symbol(name, &addr, &size) != OPAL_SUCCESS)
+		return 0;
+
+	return be64_to_cpu(addr);
+}
+
 int __init early_init_dt_scan_opal(unsigned long node,
 				   const char *uname, int depth, void *data)
 {