[PATCH] Revert "powerpc: Switch to relative jump labels"

Roman Bolshakov r.bolshakov at yadro.com
Fri May 28 11:29:43 AEST 2021


This reverts commit b0b3b2c78ec075cec4721986a95abbbac8c3da4f.

Otherwise, direct kernel boot with initramfs no longer works in QEMU.
It's broken in some bizarre way because a valid initramfs is not
recognized anymore:

  Found initrd at 0xc000000001f70000:0xc000000003d61d64
  rootfs image is not initramfs (XZ-compressed data is corrupt); looks like an initrd

The issue is observed on v5.13-rc3 if the kernel is built with
defconfig, GCC 7.5.0 and GNU ld 2.32.0.

Cc: Christophe Leroy <christophe.leroy at csgroup.eu>
Reported-by: Anastasia Kovaleva <a.kovaleva at yadro.com>
Signed-off-by: Roman Bolshakov <r.bolshakov at yadro.com>
---
 arch/powerpc/Kconfig                  |  1 -
 arch/powerpc/include/asm/jump_label.h | 21 +++++++++++++++------
 arch/powerpc/kernel/jump_label.c      |  4 ++--
 3 files changed, 17 insertions(+), 9 deletions(-)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 088dd2afcfe4..59e0d55ee01d 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -189,7 +189,6 @@ config PPC
 	select HAVE_ARCH_HUGE_VMALLOC		if HAVE_ARCH_HUGE_VMAP
 	select HAVE_ARCH_HUGE_VMAP		if PPC_BOOK3S_64 && PPC_RADIX_MMU
 	select HAVE_ARCH_JUMP_LABEL
-	select HAVE_ARCH_JUMP_LABEL_RELATIVE
 	select HAVE_ARCH_KASAN			if PPC32 && PPC_PAGE_SHIFT <= 14
 	select HAVE_ARCH_KASAN_VMALLOC		if PPC32 && PPC_PAGE_SHIFT <= 14
 	select HAVE_ARCH_KFENCE			if PPC32
diff --git a/arch/powerpc/include/asm/jump_label.h b/arch/powerpc/include/asm/jump_label.h
index 2d5c6bec2b4f..09297ec9fa52 100644
--- a/arch/powerpc/include/asm/jump_label.h
+++ b/arch/powerpc/include/asm/jump_label.h
@@ -20,8 +20,7 @@ static __always_inline bool arch_static_branch(struct static_key *key, bool bran
 	asm_volatile_goto("1:\n\t"
 		 "nop # arch_static_branch\n\t"
 		 ".pushsection __jump_table,  \"aw\"\n\t"
-		 ".long 1b - ., %l[l_yes] - .\n\t"
-		 JUMP_ENTRY_TYPE "%c0 - .\n\t"
+		 JUMP_ENTRY_TYPE "1b, %l[l_yes], %c0\n\t"
 		 ".popsection \n\t"
 		 : :  "i" (&((char *)key)[branch]) : : l_yes);
 
@@ -35,8 +34,7 @@ static __always_inline bool arch_static_branch_jump(struct static_key *key, bool
 	asm_volatile_goto("1:\n\t"
 		 "b %l[l_yes] # arch_static_branch_jump\n\t"
 		 ".pushsection __jump_table,  \"aw\"\n\t"
-		 ".long 1b - ., %l[l_yes] - .\n\t"
-		 JUMP_ENTRY_TYPE "%c0 - .\n\t"
+		 JUMP_ENTRY_TYPE "1b, %l[l_yes], %c0\n\t"
 		 ".popsection \n\t"
 		 : :  "i" (&((char *)key)[branch]) : : l_yes);
 
@@ -45,12 +43,23 @@ static __always_inline bool arch_static_branch_jump(struct static_key *key, bool
 	return true;
 }
 
+#ifdef CONFIG_PPC64
+typedef u64 jump_label_t;
+#else
+typedef u32 jump_label_t;
+#endif
+
+struct jump_entry {
+	jump_label_t code;
+	jump_label_t target;
+	jump_label_t key;
+};
+
 #else
 #define ARCH_STATIC_BRANCH(LABEL, KEY)		\
 1098:	nop;					\
 	.pushsection __jump_table, "aw";	\
-	.long 1098b - ., LABEL - .;		\
-	FTR_ENTRY_LONG KEY;			\
+	FTR_ENTRY_LONG 1098b, LABEL, KEY;	\
 	.popsection
 #endif
 
diff --git a/arch/powerpc/kernel/jump_label.c b/arch/powerpc/kernel/jump_label.c
index ce87dc5ea23c..144858027fa3 100644
--- a/arch/powerpc/kernel/jump_label.c
+++ b/arch/powerpc/kernel/jump_label.c
@@ -11,10 +11,10 @@
 void arch_jump_label_transform(struct jump_entry *entry,
 			       enum jump_label_type type)
 {
-	struct ppc_inst *addr = (struct ppc_inst *)jump_entry_code(entry);
+	struct ppc_inst *addr = (struct ppc_inst *)(unsigned long)entry->code;
 
 	if (type == JUMP_LABEL_JMP)
-		patch_branch(addr, jump_entry_target(entry), 0);
+		patch_branch(addr, entry->target, 0);
 	else
 		patch_instruction(addr, ppc_inst(PPC_INST_NOP));
 }
-- 
2.31.1



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