linux.git/arch/powerpc/kernel/btext.c, branch v6.18.22

powerpc: Add reloc_offset() to font bitmap pointer used for bootx_printf()

2026-01-02T11:57:20+00:00

commit b94b73567561642323617155bf4ee24ef0d258fe upstream.

Since Linux v6.7, booting using BootX on an Old World PowerMac produces
an early crash. Stan Johnson writes, "the symptoms are that the screen
goes blank and the backlight stays on, and the system freezes (Linux
doesn't boot)."

Further testing revealed that the failure can be avoided by disabling
CONFIG_BOOTX_TEXT. Bisection revealed that the regression was caused by
a change to the font bitmap pointer that's used when btext_init() begins
painting characters on the display, early in the boot process.

Christophe Leroy explains, "before kernel text is relocated to its final
location ... data is addressed with an offset which is added to the
Global Offset Table (GOT) entries at the start of bootx_init()
by function reloc_got2(). But the pointers that are located inside a
structure are not referenced in the GOT and are therefore not updated by
reloc_got2(). It is therefore needed to apply the offset manually by using
PTRRELOC() macro."

Cc: stable@vger.kernel.org
Link: https://lists.debian.org/debian-powerpc/2025/10/msg00111.html
Link: https://lore.kernel.org/linuxppc-dev/d81ddca8-c5ee-d583-d579-02b19ed95301@yahoo.com/
Reported-by: Cedar Maxwell 
Closes: https://lists.debian.org/debian-powerpc/2025/09/msg00031.html
Bisected-by: Stan Johnson 
Tested-by: Stan Johnson 
Fixes: 0ebc7feae79a ("powerpc: Use shared font data")
Suggested-by: Christophe Leroy 
Signed-off-by: Finn Thain 
Reviewed-by: Christophe Leroy 
Signed-off-by: Madhavan Srinivasan 
Link: https://patch.msgid.link/22b3b247425a052b079ab84da926706b3702c2c7.1762731022.git.fthain@linux-m68k.org
Signed-off-by: Greg Kroah-Hartman

powerpc: Use shared font data

2023-10-01T12:09:02+00:00

PowerPC has a 'btext' font used for the console which is almost identical
to the shared font_sun8x16, so use it rather than duplicating the data.

They were actually identical until about a decade ago when
   commit bcfbeecea11c ("drivers: console: font_: Change a glyph from
                        "broken bar" to "vertical line"")

which changed the | in the shared font to be a solid
bar rather than a broken bar.  That's the only difference.

This was originally spotted by the PMF source code analyser, which
noticed that sparc does the same thing with the same data, and they
also share a bunch of functions to manipulate the data.  I've previously
posted a near identical patch for sparc.

Tested very lightly with a boot without FS in qemu.

Signed-off-by: "Dr. David Alan Gilbert" 
Signed-off-by: Michael Ellerman 
Link: https://msgid.link/20230825142754.1487900-1-linux@treblig.org

powerpc: Use of_property_read_bool() for boolean properties

2023-03-30T12:36:35+00:00

It is preferred to use typed property access functions (i.e.
of_property_read_ functions) rather than low-level
of_get_property/of_find_property functions for reading properties.
Convert reading boolean properties to of_property_read_bool().

Signed-off-by: Rob Herring 
Signed-off-by: Michael Ellerman 
Link: https://msgid.link/20230310144659.1541127-1-robh@kernel.org

powerpc: Fix all occurences of duplicate words

2022-07-25T02:05:15+00:00

Since commit 87c78b612f4f ("powerpc: Fix all occurences of "the the"")
fixed "the the", there's now a steady stream of patches fixing other
duplicate words.

Just fix them all at once, to save the overhead of dealing with
individual patches for each case.

This leaves a few cases of "that that", which in some contexts is
correct.

Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20220718095158.326606-1-mpe@ellerman.id.au

powerpc: Add missing headers

2022-05-08T12:15:40+00:00

Don't inherit headers "by chances" from asm/prom.h, asm/mpc52xx.h,
asm/pci.h etc...

Include the needed headers, and remove asm/prom.h when it was
needed exclusively for pulling necessary headers.

Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/be8bdc934d152a7d8ee8d1a840d5596e2f7d85e0.1646767214.git.christophe.leroy@csgroup.eu

powerpc: make 'boot_text_mapped' static

2022-05-04T09:37:43+00:00

The sparse tool complains as follow:

arch/powerpc/kernel/btext.c:48:5: warning:
 symbol 'boot_text_mapped' was not declared. Should it be static?

This symbol is not used outside of btext.c, so this commit make
it static.

Signed-off-by: Yu Kuai 
Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20210408011801.557004-3-yukuai3@huawei.com

powerpc: remove set but not used variable 'force_printk_to_btext'

2022-05-04T09:37:43+00:00

Fixes gcc '-Wunused-but-set-variable' warning:

arch/powerpc/kernel/btext.c:49:12: error: 'force_printk_to_btext'
defined but not used.

It is never used, and so can be removed.

Signed-off-by: Yu Kuai 
Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20210408011801.557004-2-yukuai3@huawei.com

powerpc/kernel: Add __init attribute to eligible functions

2021-12-23T11:33:10+00:00

Some functions defined in `arch/powerpc/kernel` (and one in `arch/powerpc/
kexec`) are deserving of an `__init` macro attribute. These functions are
only called by other initialization functions and therefore should inherit
the attribute.
Also, change function declarations in header files to include `__init`.

Signed-off-by: Nick Child 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20211216220035.605465-2-nick.child@ibm.com

powerpc/btext: add missing of_node_put

2021-11-25T00:25:29+00:00

for_each_node_by_type performs an of_node_get on each iteration, so
a break out of the loop requires an of_node_put.

A simplified version of the semantic patch that fixes this problem is as
follows (http://coccinelle.lip6.fr):

// 
@@
local idexpression n;
expression e;
@@

 for_each_node_by_type(n,...) {
   ...
(
   of_node_put(n);
|
   e = n
|
+  of_node_put(n);
?  break;
)
   ...
 }
... when != n
// 

Signed-off-by: Julia Lawall 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/1448051604-25256-6-git-send-email-Julia.Lawall@lip6.fr

treewide: Convert macro and uses of section(foo) to section("foo")

2020-10-25T21:51:49+00:00

Use a more generic form for __section that requires quotes to avoid
complications with clang and gcc differences.

Remove the quote operator # from compiler_attributes.h __section macro.

Convert all unquoted __section(foo) uses to quoted __section("foo").
Also convert __attribute__((section("foo"))) uses to __section("foo")
even if the __attribute__ has multiple list entry forms.

Conversion done using the script at:

    https://lore.kernel.org/lkml/75393e5ddc272dc7403de74d645e6c6e0f4e70eb.camel@perches.com/2-convert_section.pl

Signed-off-by: Joe Perches 
Reviewed-by: Nick Desaulniers 
Reviewed-by: Miguel Ojeda 
Signed-off-by: Linus Torvalds