linux-stable.git/arch/powerpc/kernel/prom.c, branch linux-3.16.y

powerpc: scan_features() updates incorrect bits for REAL_LE

2016-06-15T20:29:25+00:00

commit 6997e57d693b07289694239e52a10d2f02c3a46f upstream.

The REAL_LE feature entry in the ibm_pa_feature struct is missing an MMU
feature value, meaning all the remaining elements initialise the wrong
values.

This means instead of checking for byte 5, bit 0, we check for byte 0,
bit 0, and then we incorrectly set the CPU feature bit as well as MMU
feature bit 1 and CPU user feature bits 0 and 2 (5).

Checking byte 0 bit 0 (IBM numbering), means we're looking at the
"Memory Management Unit (MMU)" feature - ie. does the CPU have an MMU.
In practice that bit is set on all platforms which have the property.

This means we set CPU_FTR_REAL_LE always. In practice that seems not to
matter because all the modern cpus which have this property also
implement REAL_LE, and we've never needed to disable it.

We're also incorrectly setting MMU feature bit 1, which is:

#define MMU_FTR_TYPE_8xx 0x00000002

Luckily the only place that looks for MMU_FTR_TYPE_8xx is in Book3E
code, which can't run on the same cpus as scan_features(). So this also
doesn't matter in practice.

Finally in the CPU user feature mask, we're setting bits 0 and 2. Bit 2
is not currently used, and bit 0 is:

#define PPC_FEATURE_PPC_LE 0x00000001

Which says the CPU supports the old style "PPC Little Endian" mode.
Again this should be harmless in practice as no 64-bit CPUs implement
that mode.

Fix the code by adding the missing initialisation of the MMU feature.

Also add a comment marking CPU user feature bit 2 (0x4) as reserved. It
would be unsafe to start using it as old kernels incorrectly set it.

Fixes: 44ae3ab3358e ("powerpc: Free up some CPU feature bits by moving out MMU-related features")
Signed-off-by: Anton Blanchard
[mpe: Flesh out changelog, add comment reserving 0x4]
Signed-off-by: Michael Ellerman
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings

powerpc/powernv: Remove OPAL v1 takeover

2014-06-25T03:10:47+00:00

In commit 27f4488872d9 "Add OPAL takeover from PowerVM" we added support
for "takeover" on OPAL v1 machines.

This was a mode of operation where we would boot under pHyp, and query
for the presence of OPAL. If detected we would then do a special
sequence to take over the machine, and the kernel would end up running
in hypervisor mode.

OPAL v1 was never a supported product, and was never shipped outside
IBM. As far as we know no one is still using it.

Newer versions of OPAL do not use the takeover mechanism. Although the
query for OPAL should be harmless on machines with newer OPAL, we have
seen a machine where it causes a crash in Open Firmware.

The code in early_init_devtree() to copy boot_command_line into cmd_line
was added in commit 817c21ad9a1f "Get kernel command line accross OPAL
takeover", and AFAIK is only used by takeover, so should also be
removed.

Signed-off-by: Michael Ellerman 
Signed-off-by: Benjamin Herrenschmidt

powerpc: use libfdt accessors for header data

2014-04-30T05:59:18+00:00

With libfdt support, we can take advantage of helper accessors in libfdt
for accessing the FDT header data. This makes the code more readable and
makes the FDT blob structure more opaque to the kernel. This also
prepares for removing struct boot_param_header completely.

Signed-off-by: Rob Herring 
Cc: Benjamin Herrenschmidt 
Cc: Paul Mackerras 
Tested-by: Grant Likely 
Tested-by: Stephen Chivers

of/fdt: move memreserve and dtb memory reservations into core

2014-04-30T05:59:17+00:00

Move the /memreserve/ processing and dtb memory reservations into
early_init_fdt_scan_reserved_mem. This converts arm, arm64, and powerpc
as they are the only users of early_init_fdt_scan_reserved_mem.

memblock_reserve is safe to call on the same region twice, so the
reservation check for the dtb in powerpc 32-bit reservations is safe to
remove.

Signed-off-by: Rob Herring 
Tested-by: Michal Simek 
Cc: Russell King 
Cc: Catalin Marinas 
Cc: Will Deacon 
Cc: Benjamin Herrenschmidt 
Cc: Paul Mackerras 
Tested-by: Grant Likely 
Tested-by: Stephen Chivers

of/fdt: create common debugfs

2014-04-30T05:59:16+00:00

Both powerpc and microblaze have the same FDT blob in debugfs feature.
Move this to common location and remove the powerpc and microblaze
implementations. This feature could become more useful when FDT
overlay support is added.

This changes the path of the blob from "$arch/flat-device-tree" to
"device-tree/flat-device-tree".

Signed-off-by: Rob Herring 
Tested-by: Michal Simek 
Cc: Michal Simek 
Cc: Benjamin Herrenschmidt 
Cc: Paul Mackerras 
Cc: linuxppc-dev@lists.ozlabs.org
Tested-by: Grant Likely 
Tested-by: Stephen Chivers

of/fdt: update of_get_flat_dt_prop in prep for libfdt

2014-04-30T05:59:15+00:00

Make of_get_flat_dt_prop arguments compatible with libfdt fdt_getprop
call in preparation to convert FDT code to use libfdt. Make the return
value const and the property length ptr type an int.

Signed-off-by: Rob Herring 
Tested-by: Michal Simek 
Tested-by: Grant Likely 
Tested-by: Stephen Chivers

powerpc: fix skipping call to early_init_fdt_scan_reserved_mem

2014-04-30T05:59:04+00:00

The call to early_init_fdt_scan_reserved_mem will be skipped if
reserved-ranges is not found. Move the call earlier so that it is called
unconditionally.

Signed-off-by: Rob Herring 
Cc: Marek Szyprowski 
Cc: Benjamin Herrenschmidt 
Cc: Paul Mackerras 
Cc: linuxppc-dev@lists.ozlabs.org
Tested-by: Stephen Chivers

powerpc/prom: early_init_dt_scan_cpus() updates cpu features only once

2014-04-07T00:33:14+00:00

All our cpu feature updates were done for every CPU in the device-tree,
thus overwriting the cputable bits over and over again. Instead do them
only for the boot CPU.

Signed-off-by: Benjamin Herrenschmidt

powerpc: Make boot_cpuid common between 32 and 64-bit

2014-04-07T00:33:14+00:00

Move the definition to setup-common.c and set the init value
to -1 on both 32 and 64-bit (it was 0 on 64-bit).

Additionally add a check to prom.c to garantee that the init
value has been udpated after the DT scan.

Signed-off-by: Benjamin Herrenschmidt

powerpc: Adjust CPU_FTR_SMT on all platforms

2014-04-07T00:33:13+00:00

For historical reasons that code was under #ifdef CONFIG_PPC_PSERIES
but it applies equally to all 64-bit platforms.

Signed-off-by: Benjamin Herrenschmidt