| Message ID | 20230224032508.3331281-1-mpe@ellerman.id.au (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/2] powerpc/tpm: Create linux,sml-base/size as big endian | expand |
On 2/23/23 22:25, Michael Ellerman wrote: > There's code in prom_instantiate_sml() to do a "SML handover" (Stored > Measurement Log) from OF to Linux, before Linux shuts down Open > Firmware. > > This involves creating a buffer to hold the SML, and creating two device > tree properties to record its base address and size. The kernel then > later reads those properties from the device tree to find the SML. > > When the code was initially added in commit 4a727429abec ("PPC64: Add > support for instantiating SML from Open Firmware") the powerpc kernel > was always built big endian, so the properties were created big endian > by default. > > However since then little endian support was added to powerpc, and now > the code lacks conversions to big endian when creating the properties. > > This means on little endian kernels the device tree properties are > little endian, which is contrary to the device tree spec, and in > contrast to all other device tree properties. > > To cope with that a workaround was added in tpm_read_log_of() to skip > the endian conversion if the properties were created via the SML > handover. > > A better solution is to encode the properties as big endian as they > should be, and remove the workaround. > > Typically changing the encoding of a property like this would present > problems for kexec. However the SML is not propagated across kexec, so > changing the encoding of the properties is a non-issue. > > Fixes: e46e22f12b19 ("tpm: enhance read_log_of() to support Physical TPM event log") > Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
On Mon, Feb 27, 2023 at 06:08:31PM -0500, Stefan Berger wrote: > > > On 2/23/23 22:25, Michael Ellerman wrote: > > There's code in prom_instantiate_sml() to do a "SML handover" (Stored > > Measurement Log) from OF to Linux, before Linux shuts down Open > > Firmware. > > > > This involves creating a buffer to hold the SML, and creating two device > > tree properties to record its base address and size. The kernel then > > later reads those properties from the device tree to find the SML. > > > > When the code was initially added in commit 4a727429abec ("PPC64: Add > > support for instantiating SML from Open Firmware") the powerpc kernel > > was always built big endian, so the properties were created big endian > > by default. > > > > However since then little endian support was added to powerpc, and now > > the code lacks conversions to big endian when creating the properties. > > > > This means on little endian kernels the device tree properties are > > little endian, which is contrary to the device tree spec, and in > > contrast to all other device tree properties. > > > > To cope with that a workaround was added in tpm_read_log_of() to skip > > the endian conversion if the properties were created via the SML > > handover. > > > > A better solution is to encode the properties as big endian as they > > should be, and remove the workaround. > > > > Typically changing the encoding of a property like this would present > > problems for kexec. However the SML is not propagated across kexec, so > > changing the encoding of the properties is a non-issue. > > > > Fixes: e46e22f12b19 ("tpm: enhance read_log_of() to support Physical TPM event log") > > Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> > > Reviewed-by: Stefan Berger <stefanb@linux.ibm.com> 2/2 does not have a fixes tag. BR, Jarkko
Jarkko Sakkinen <jarkko@kernel.org> writes: > On Mon, Feb 27, 2023 at 06:08:31PM -0500, Stefan Berger wrote: >> On 2/23/23 22:25, Michael Ellerman wrote: >> > There's code in prom_instantiate_sml() to do a "SML handover" (Stored >> > Measurement Log) from OF to Linux, before Linux shuts down Open >> > Firmware. >> > >> > This involves creating a buffer to hold the SML, and creating two device >> > tree properties to record its base address and size. The kernel then >> > later reads those properties from the device tree to find the SML. >> > >> > When the code was initially added in commit 4a727429abec ("PPC64: Add >> > support for instantiating SML from Open Firmware") the powerpc kernel >> > was always built big endian, so the properties were created big endian >> > by default. >> > >> > However since then little endian support was added to powerpc, and now >> > the code lacks conversions to big endian when creating the properties. >> > >> > This means on little endian kernels the device tree properties are >> > little endian, which is contrary to the device tree spec, and in >> > contrast to all other device tree properties. >> > >> > To cope with that a workaround was added in tpm_read_log_of() to skip >> > the endian conversion if the properties were created via the SML >> > handover. >> > >> > A better solution is to encode the properties as big endian as they >> > should be, and remove the workaround. >> > >> > Typically changing the encoding of a property like this would present >> > problems for kexec. However the SML is not propagated across kexec, so >> > changing the encoding of the properties is a non-issue. >> > >> > Fixes: e46e22f12b19 ("tpm: enhance read_log_of() to support Physical TPM event log") >> > Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> >> >> Reviewed-by: Stefan Berger <stefanb@linux.ibm.com> > > 2/2 does not have a fixes tag. True. Arguably the bug goes back to the introduction of kexec_file_load() support, although the patch won't backport that far due to code refactoring. So that would be: Fixes: a0458284f062 ("powerpc: Add support code for kexec_file_load()") cheers
On Tue, Feb 28, 2023 at 10:21:36PM +1100, Michael Ellerman wrote: > Jarkko Sakkinen <jarkko@kernel.org> writes: > > On Mon, Feb 27, 2023 at 06:08:31PM -0500, Stefan Berger wrote: > >> On 2/23/23 22:25, Michael Ellerman wrote: > >> > There's code in prom_instantiate_sml() to do a "SML handover" (Stored > >> > Measurement Log) from OF to Linux, before Linux shuts down Open > >> > Firmware. > >> > > >> > This involves creating a buffer to hold the SML, and creating two device > >> > tree properties to record its base address and size. The kernel then > >> > later reads those properties from the device tree to find the SML. > >> > > >> > When the code was initially added in commit 4a727429abec ("PPC64: Add > >> > support for instantiating SML from Open Firmware") the powerpc kernel > >> > was always built big endian, so the properties were created big endian > >> > by default. > >> > > >> > However since then little endian support was added to powerpc, and now > >> > the code lacks conversions to big endian when creating the properties. > >> > > >> > This means on little endian kernels the device tree properties are > >> > little endian, which is contrary to the device tree spec, and in > >> > contrast to all other device tree properties. > >> > > >> > To cope with that a workaround was added in tpm_read_log_of() to skip > >> > the endian conversion if the properties were created via the SML > >> > handover. > >> > > >> > A better solution is to encode the properties as big endian as they > >> > should be, and remove the workaround. > >> > > >> > Typically changing the encoding of a property like this would present > >> > problems for kexec. However the SML is not propagated across kexec, so > >> > changing the encoding of the properties is a non-issue. > >> > > >> > Fixes: e46e22f12b19 ("tpm: enhance read_log_of() to support Physical TPM event log") > >> > Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> > >> > >> Reviewed-by: Stefan Berger <stefanb@linux.ibm.com> > > > > 2/2 does not have a fixes tag. > > True. Arguably the bug goes back to the introduction of > kexec_file_load() support, although the patch won't backport that far > due to code refactoring. So that would be: > > Fixes: a0458284f062 ("powerpc: Add support code for kexec_file_load()") Hmm... IMHO, it would still make sense to document this. BR, Jarkko
diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c index d464ba412084..72fe306b6820 100644 --- a/arch/powerpc/kernel/prom_init.c +++ b/arch/powerpc/kernel/prom_init.c @@ -1900,6 +1900,7 @@ static void __init prom_instantiate_sml(void) u32 entry = 0, size = 0, succ = 0; u64 base; __be32 val; + __be64 val64; prom_debug("prom_instantiate_sml: start...\n"); @@ -1956,10 +1957,13 @@ static void __init prom_instantiate_sml(void) reserve_mem(base, size); + val64 = cpu_to_be64(base); prom_setprop(ibmvtpm_node, "/vdevice/vtpm", "linux,sml-base", - &base, sizeof(base)); + &val64, sizeof(val64)); + + val = cpu_to_be32(size); prom_setprop(ibmvtpm_node, "/vdevice/vtpm", "linux,sml-size", - &size, sizeof(size)); + &val, sizeof(val)); prom_debug("sml base = 0x%llx\n", base); prom_debug("sml size = 0x%x\n", size); diff --git a/drivers/char/tpm/eventlog/of.c b/drivers/char/tpm/eventlog/of.c index 930fe43d5daf..0bc0cb6333c6 100644 --- a/drivers/char/tpm/eventlog/of.c +++ b/drivers/char/tpm/eventlog/of.c @@ -51,8 +51,8 @@ static int tpm_read_log_memory_region(struct tpm_chip *chip) int tpm_read_log_of(struct tpm_chip *chip) { struct device_node *np; - const u32 *sizep; - const u64 *basep; + const __be32 *sizep; + const __be64 *basep; struct tpm_bios_log *log; u32 size; u64 base; @@ -73,23 +73,8 @@ int tpm_read_log_of(struct tpm_chip *chip) if (sizep == NULL || basep == NULL) return -EIO; - /* - * For both vtpm/tpm, firmware has log addr and log size in big - * endian format. But in case of vtpm, there is a method called - * sml-handover which is run during kernel init even before - * device tree is setup. This sml-handover function takes care - * of endianness and writes to sml-base and sml-size in little - * endian format. For this reason, vtpm doesn't need conversion - * but physical tpm needs the conversion. - */ - if (of_property_match_string(np, "compatible", "IBM,vtpm") < 0 && - of_property_match_string(np, "compatible", "IBM,vtpm20") < 0) { - size = be32_to_cpup((__force __be32 *)sizep); - base = be64_to_cpup((__force __be64 *)basep); - } else { - size = *sizep; - base = *basep; - } + size = be32_to_cpup(sizep); + base = be64_to_cpup(basep); if (size == 0) { dev_warn(&chip->dev, "%s: Event log area empty\n", __func__);
There's code in prom_instantiate_sml() to do a "SML handover" (Stored Measurement Log) from OF to Linux, before Linux shuts down Open Firmware. This involves creating a buffer to hold the SML, and creating two device tree properties to record its base address and size. The kernel then later reads those properties from the device tree to find the SML. When the code was initially added in commit 4a727429abec ("PPC64: Add support for instantiating SML from Open Firmware") the powerpc kernel was always built big endian, so the properties were created big endian by default. However since then little endian support was added to powerpc, and now the code lacks conversions to big endian when creating the properties. This means on little endian kernels the device tree properties are little endian, which is contrary to the device tree spec, and in contrast to all other device tree properties. To cope with that a workaround was added in tpm_read_log_of() to skip the endian conversion if the properties were created via the SML handover. A better solution is to encode the properties as big endian as they should be, and remove the workaround. Typically changing the encoding of a property like this would present problems for kexec. However the SML is not propagated across kexec, so changing the encoding of the properties is a non-issue. Fixes: e46e22f12b19 ("tpm: enhance read_log_of() to support Physical TPM event log") Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> --- arch/powerpc/kernel/prom_init.c | 8 ++++++-- drivers/char/tpm/eventlog/of.c | 23 ++++------------------- 2 files changed, 10 insertions(+), 21 deletions(-)