[PATCH] sparc32: Fix truncated relocation errors when linking large kernels

From: Andreas Larsson
Date: Wed Jul 10 2024 - 05:32:38 EST


Use jumps instead of branches when jumping from one section to another
to avoid branches to addresses further away than 22 bit offsets can
handle that results in errors such as

arch/sparc/kernel/signal_32.o:(.fixup+0x0): relocation truncated to fit: R_SPARC_WDISP22 against `.text'

This is the same approach that was taken for sparc64 in commit
52eb053b7191 ("[SPARC64]: Fix linkage of enormous kernels.")

Reported-by: kernel test robot <lkp@xxxxxxxxx>
Closes: https://lore.kernel.org/oe-kbuild-all/202405080936.tWaJdO3P-lkp@xxxxxxxxx/
Closes: https://lore.kernel.org/oe-kbuild-all/202406240441.5zaoshVX-lkp@xxxxxxxxx/
Signed-off-by: Andreas Larsson <andreas@xxxxxxxxxxx>
---
arch/sparc/include/asm/uaccess_32.h | 6 ++++--
arch/sparc/kernel/head_32.S | 15 +++++++++++----
2 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/arch/sparc/include/asm/uaccess_32.h b/arch/sparc/include/asm/uaccess_32.h
index 9fd6c53644b6..43284b6ec46a 100644
--- a/arch/sparc/include/asm/uaccess_32.h
+++ b/arch/sparc/include/asm/uaccess_32.h
@@ -95,7 +95,8 @@ __asm__ __volatile__( \
".section .fixup,#alloc,#execinstr\n\t" \
".align 4\n" \
"3:\n\t" \
- "b 2b\n\t" \
+ "sethi %%hi(2b), %0\n\t" \
+ "jmpl %0 + %%lo(2b), %%g0\n\t" \
" mov %3, %0\n\t" \
".previous\n\n\t" \
".section __ex_table,#alloc\n\t" \
@@ -163,8 +164,9 @@ __asm__ __volatile__( \
".section .fixup,#alloc,#execinstr\n\t" \
".align 4\n" \
"3:\n\t" \
+ "sethi %%hi(2b), %0\n\t" \
"clr %1\n\t" \
- "b 2b\n\t" \
+ "jmpl %0 + %%lo(2b), %%g0\n\t" \
" mov %3, %0\n\n\t" \
".previous\n\t" \
".section __ex_table,#alloc\n\t" \
diff --git a/arch/sparc/kernel/head_32.S b/arch/sparc/kernel/head_32.S
index 964c61b5cd03..38345460d542 100644
--- a/arch/sparc/kernel/head_32.S
+++ b/arch/sparc/kernel/head_32.S
@@ -118,9 +118,12 @@ current_pc:
mov %o7, %g3

tst %o0
- be no_sun4u_here
+ bne 2f
mov %g4, %o7 /* Previous %o7. */
-
+ sethi %hi(no_sun4u_here), %l1
+ jmpl %l1 + %lo(no_sun4u_here), %g0
+ nop
+2:
mov %o0, %l0 ! stash away romvec
mov %o0, %g7 ! put it here too
mov %o1, %l1 ! stash away debug_vec too
@@ -195,7 +198,8 @@ halt_notsup:
sub %o0, %l6, %o0
call %o1
nop
- ba halt_me
+ sethi %hi(halt_me), %o0
+ jmpl %o0 + %lo(halt_me), %g0
nop

not_a_sun4:
@@ -431,8 +435,11 @@ leon_init:
#ifdef CONFIG_SMP
ldub [%g2 + %lo(boot_cpu_id)], %g1
cmp %g1, 0xff ! unset means first CPU
- bne leon_smp_cpu_startup ! continue only with master
+ be 1f
+ sethi %hi(leon_smp_cpu_startup), %g1
+ jmpl %g1 + %lo(leon_smp_cpu_startup), %g0
nop
+1:
#endif
/* Get CPU-ID from most significant 4-bit of ASR17 */
rd %asr17, %g1
--
2.34.1