[PATCH v1 1/3] powerpc/code-patching: Improve verification of patchability

Subsystems: linux for powerpc (32-bit and 64-bit), the rest

STALE1808d

3 messages, 1 author, 2021-09-24 · open the first message on its own page

[PATCH v1 1/3] powerpc/code-patching: Improve verification of patchability

From: Christophe Leroy <hidden>
Date: 2021-09-24 12:38:36

Today, patch_instruction() assumes that is called exclusively on valid
addresses, and only checks that it is not called on an init address
after init section has been freed.

Improve verification by calling kernel_text_address() instead.

kernel_text_address() already includes a verification of
initmem release.

Cc: Michael Neuling <redacted>
Signed-off-by: Christophe Leroy <redacted>
---
 arch/powerpc/lib/code-patching.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c
index f9a3019e37b4..20ec6648aacc 100644
--- a/arch/powerpc/lib/code-patching.c
+++ b/arch/powerpc/lib/code-patching.c

@@ -190,10 +190,9 @@ static int do_patch_instruction(u32 *addr, struct ppc_inst instr)
 int patch_instruction(u32 *addr, struct ppc_inst instr)
 {
 	/* Make sure we aren't patching a freed init section */
-	if (init_mem_is_free && init_section_contains(addr, 4)) {
-		pr_debug("Skipping init section patching addr: 0x%px\n", addr);
+	if (!kernel_text_address((unsigned long)addr))
 		return 0;
-	}
+
 	return do_patch_instruction(addr, instr);
 }
 NOKPROBE_SYMBOL(patch_instruction);

-- 
2.31.1

[PATCH v1 3/3] powerpc: Remove init_mem_is_free

From: Christophe Leroy <hidden>
Date: 2021-09-24 12:38:40

init_mem_is_free is not used anymore. Remove it.

Cc: Michael Neuling <redacted>
Signed-off-by: Christophe Leroy <redacted>
---
 arch/powerpc/include/asm/sections.h | 2 --
 arch/powerpc/include/asm/setup.h    | 1 -
 arch/powerpc/mm/mem.c               | 2 --
 3 files changed, 5 deletions(-)

diff --git a/arch/powerpc/include/asm/sections.h b/arch/powerpc/include/asm/sections.h
index dff55421f76b..454b8434bfc4 100644
--- a/arch/powerpc/include/asm/sections.h
+++ b/arch/powerpc/include/asm/sections.h

@@ -10,8 +10,6 @@
 
 #include <asm-generic/sections.h>
 
-extern bool init_mem_is_free;
-
 static inline int arch_is_kernel_initmem_freed(unsigned long addr)
 {
 	if (system_state < SYSTEM_RUNNING)

diff --git a/arch/powerpc/include/asm/setup.h b/arch/powerpc/include/asm/setup.h
index 6c1a7d217d1a..426a2d8d028f 100644
--- a/arch/powerpc/include/asm/setup.h
+++ b/arch/powerpc/include/asm/setup.h

@@ -9,7 +9,6 @@ extern void ppc_printk_progress(char *s, unsigned short hex);
 
 extern unsigned int rtas_data;
 extern unsigned long long memory_limit;
-extern bool init_mem_is_free;
 extern void *zalloc_maybe_bootmem(size_t size, gfp_t mask);
 
 struct device_node;

diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index c3c4e31462ec..5b1eae6c0356 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c

@@ -26,7 +26,6 @@
 #include <mm/mmu_decl.h>
 
 unsigned long long memory_limit;
-bool init_mem_is_free;
 
 unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)] __page_aligned_bss;
 EXPORT_SYMBOL(empty_zero_page);

@@ -312,7 +311,6 @@ void free_initmem(void)
 {
 	ppc_md.progress = ppc_printk_progress;
 	mark_initmem_nx();
-	init_mem_is_free = true;
 	free_initmem_default(POISON_FREE_INITMEM);
 }

-- 
2.31.1

[PATCH v1 2/3] powerpc: Stop using init_mem_is_free

From: Christophe Leroy <hidden>
Date: 2021-09-24 12:38:43

Generic parts of the kernel for instance core_kernel_text()
use 'system_state' to check whether init memory has been
freed.

Do the same and stop using init_mem_is_free.

Cc: Michael Neuling <redacted>
Signed-off-by: Christophe Leroy <redacted>
---
 arch/powerpc/include/asm/sections.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/sections.h b/arch/powerpc/include/asm/sections.h
index 6e4af4492a14..dff55421f76b 100644
--- a/arch/powerpc/include/asm/sections.h
+++ b/arch/powerpc/include/asm/sections.h

@@ -14,7 +14,7 @@ extern bool init_mem_is_free;
 
 static inline int arch_is_kernel_initmem_freed(unsigned long addr)
 {
-	if (!init_mem_is_free)
+	if (system_state < SYSTEM_RUNNING)
 		return 0;
 
 	return addr >= (unsigned long)__init_begin &&

-- 
2.31.1

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