ARM: ftrace MODULE_PLTS warning fixes

PATCH In review Florian Fainelli 2 participants 6 messages Sep 22, 2021 Stable branch

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Florian Fainelli

author

2021-09-22 02:40 UTC #0 lore raw

cover ARM: ftrace MODULE_PLTS warning fixes

This patch series is present in v5.14 and fixes warnings seen at insmod with FTRACE and MODULE_PLTS enabled on ARM/Linux.

Alex Sverdlin (3):
ARM: 9077/1: PLT: Move struct plt_entries definition to header
ARM: 9078/1: Add warn suppress parameter to arm_gen_branch_link()
ARM: 9079/1: ftrace: Add MODULE_PLTS support

 arch/arm/include/asm/ftrace.h |  3 +++
 arch/arm/include/asm/insn.h   |  8 +++---
 arch/arm/include/asm/module.h | 10 +++++++
 arch/arm/kernel/ftrace.c      | 46 ++++++++++++++++++++++++++------
 arch/arm/kernel/insn.c        | 19 +++++++-------
 arch/arm/kernel/module-plts.c | 49 +++++++++++++++++++++++++++--------
 6 files changed, 103 insertions(+), 32 deletions(-)

Signature · 1 line

2.25.1

Florian Fainelli

author

2021-09-22 02:40 UTC #1 lore raw

PATCH 1/3 ARM: 9077/1: PLT: Move struct plt_entries definition to header

From: Alex Sverdlin <[email protected]>

commit 4e271701c17dee70c6e1351c4d7d42e70405c6a9 upstream upstream

No functional change, later it will be re-used in several files.

Signed-off-by Alexander Sverdlin <[email protected]>

Signed-off-by Russell King <[email protected]>

Signed-off-by Florian Fainelli <[email protected]>

---
 arch/arm/include/asm/module.h | 9 +++++++++
 arch/arm/kernel/module-plts.c | 9 ---------
 2 files changed, 9 insertions(+), 9 deletions(-)

arch/arm/include/asm/module.h +9 -0

index 4b0df09cbe67..09b9ad55b83d 100644
@@ -19,6 +19,15 @@ enum {
 };
 #endif
 
+#define PLT_ENT_STRIDE		L1_CACHE_BYTES
+#define PLT_ENT_COUNT		(PLT_ENT_STRIDE / sizeof(u32))
+#define PLT_ENT_SIZE		(sizeof(struct plt_entries) / PLT_ENT_COUNT)
+
+struct plt_entries {
+	u32	ldr[PLT_ENT_COUNT];
+	u32	lit[PLT_ENT_COUNT];
+};
+
 struct mod_plt_sec {
 	struct elf32_shdr	*plt;
 	int			plt_count;

arch/arm/kernel/module-plts.c +0 -9

index 6e626abaefc5..d330e9ec2de3 100644
@@ -12,10 +12,6 @@
 #include <asm/cache.h>
 #include <asm/opcodes.h>
 
-#define PLT_ENT_STRIDE		L1_CACHE_BYTES
-#define PLT_ENT_COUNT		(PLT_ENT_STRIDE / sizeof(u32))
-#define PLT_ENT_SIZE		(sizeof(struct plt_entries) / PLT_ENT_COUNT)
-
 #ifdef CONFIG_THUMB2_KERNEL
 #define PLT_ENT_LDR		__opcode_to_mem_thumb32(0xf8dff000 | \
 							(PLT_ENT_STRIDE - 4))

@@ -24,11 +20,6 @@
 						    (PLT_ENT_STRIDE - 8))
 #endif
 
-struct plt_entries {
-	u32	ldr[PLT_ENT_COUNT];
-	u32	lit[PLT_ENT_COUNT];
-};
-
 static bool in_init(const struct module *mod, unsigned long loc)
 {
 	return loc - (u32)mod->init_layout.base < mod->init_layout.size;

Signature · 1 line

2.25.1

Florian Fainelli

author

2021-09-22 02:40 UTC #2 lore raw

PATCH 2/3 ARM: 9078/1: Add warn suppress parameter to arm_gen_branch_link()

In reply to Florian Fainelli

From: Alex Sverdlin <[email protected]>

commit 890cb057a46d323fd8c77ebecb6485476614cd21 upstream

Will be used in the following patch. No functional change.

Signed-off-by Alexander Sverdlin <[email protected]>

Signed-off-by Russell King <[email protected]>

Signed-off-by Florian Fainelli <[email protected]>

---
 arch/arm/include/asm/insn.h |  8 ++++----
 arch/arm/kernel/ftrace.c    |  2 +-
 arch/arm/kernel/insn.c      | 19 ++++++++++---------
 3 files changed, 15 insertions(+), 14 deletions(-)

arch/arm/include/asm/insn.h +4 -4

index f20e08ac85ae..5475cbf9fb6b 100644
@@ -13,18 +13,18 @@ arm_gen_nop(void)
 }
 
 unsigned long
-__arm_gen_branch(unsigned long pc, unsigned long addr, bool link);
+__arm_gen_branch(unsigned long pc, unsigned long addr, bool link, bool warn);
 
 static inline unsigned long
 arm_gen_branch(unsigned long pc, unsigned long addr)
 {
-	return __arm_gen_branch(pc, addr, false);
+	return __arm_gen_branch(pc, addr, false, true);
 }
 
 static inline unsigned long
-arm_gen_branch_link(unsigned long pc, unsigned long addr)
+arm_gen_branch_link(unsigned long pc, unsigned long addr, bool warn)
 {
-	return __arm_gen_branch(pc, addr, true);
+	return __arm_gen_branch(pc, addr, true, warn);
 }
 
 #endif

arch/arm/kernel/ftrace.c +1 -1

index 9a79ef6b1876..61de8172a044 100644
@@ -70,7 +70,7 @@ int ftrace_arch_code_modify_post_process(void)
 
 static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr)
 {
-	return arm_gen_branch_link(pc, addr);
+	return arm_gen_branch_link(pc, addr, true);
 }
 
 static int ftrace_modify_code(unsigned long pc, unsigned long old,

arch/arm/kernel/insn.c +10 -9

index 2e844b70386b..db0acbb7d7a0 100644
@@ -3,8 +3,9 @@
 #include <linux/kernel.h>
 #include <asm/opcodes.h>
 
-static unsigned long
-__arm_gen_branch_thumb2(unsigned long pc, unsigned long addr, bool link)
+static unsigned long __arm_gen_branch_thumb2(unsigned long pc,
+					     unsigned long addr, bool link,
+					     bool warn)
 {
 	unsigned long s, j1, j2, i1, i2, imm10, imm11;
 	unsigned long first, second;

@@ -12,7 +13,7 @@ __arm_gen_branch_thumb2(unsigned long pc, unsigned long addr, bool link)
 
 	offset = (long)addr - (long)(pc + 4);
 	if (offset < -16777216 || offset > 16777214) {
-		WARN_ON_ONCE(1);
+		WARN_ON_ONCE(warn);
 		return 0;
 	}

@@ -33,8 +34,8 @@ __arm_gen_branch_thumb2(unsigned long pc, unsigned long addr, bool link)
 	return __opcode_thumb32_compose(first, second);
 }
 
-static unsigned long
-__arm_gen_branch_arm(unsigned long pc, unsigned long addr, bool link)
+static unsigned long __arm_gen_branch_arm(unsigned long pc, unsigned long addr,
+					  bool link, bool warn)
 {
 	unsigned long opcode = 0xea000000;
 	long offset;

@@ -44,7 +45,7 @@ __arm_gen_branch_arm(unsigned long pc, unsigned long addr, bool link)
 
 	offset = (long)addr - (long)(pc + 8);
 	if (unlikely(offset < -33554432 || offset > 33554428)) {
-		WARN_ON_ONCE(1);
+		WARN_ON_ONCE(warn);
 		return 0;
 	}

@@ -54,10 +55,10 @@ __arm_gen_branch_arm(unsigned long pc, unsigned long addr, bool link)
 }
 
 unsigned long
-__arm_gen_branch(unsigned long pc, unsigned long addr, bool link)
+__arm_gen_branch(unsigned long pc, unsigned long addr, bool link, bool warn)
 {
 	if (IS_ENABLED(CONFIG_THUMB2_KERNEL))
-		return __arm_gen_branch_thumb2(pc, addr, link);
+		return __arm_gen_branch_thumb2(pc, addr, link, warn);
 	else
-		return __arm_gen_branch_arm(pc, addr, link);
+		return __arm_gen_branch_arm(pc, addr, link, warn);
 }

Signature · 1 line

2.25.1

Florian Fainelli

author

2021-09-22 02:40 UTC #3 lore raw

PATCH 3/3 ARM: 9079/1: ftrace: Add MODULE_PLTS support

In reply to Florian Fainelli

From: Alex Sverdlin <[email protected]>

commit 79f32b221b18c15a98507b101ef4beb52444cc6f upstream

Teach ftrace_make_call() and ftrace_make_nop() about PLTs. Teach PLT code about FTRACE and all its callbacks. Otherwise the following might happen:

------------[ cut here ]------------
WARNING: CPU: 14 PID: 2265 at .../arch/arm/kernel/insn.c:14 __arm_gen_branch+0x83/0x8c()
...
Hardware name: LSI Axxia AXM55XX
[<c0314a49>] (unwind_backtrace) from [<c03115e9>] (show_stack+0x11/0x14)
[<c03115e9>] (show_stack) from [<c0519f51>] (dump_stack+0x81/0xa8)
[<c0519f51>] (dump_stack) from [<c032185d>] (warn_slowpath_common+0x69/0x90)
[<c032185d>] (warn_slowpath_common) from [<c03218f3>] (warn_slowpath_null+0x17/0x1c)
[<c03218f3>] (warn_slowpath_null) from [<c03143cf>] (__arm_gen_branch+0x83/0x8c)
[<c03143cf>] (__arm_gen_branch) from [<c0314337>] (ftrace_make_nop+0xf/0x24)
[<c0314337>] (ftrace_make_nop) from [<c038ebcb>] (ftrace_process_locs+0x27b/0x3e8)
[<c038ebcb>] (ftrace_process_locs) from [<c0378d79>] (load_module+0x11e9/0x1a44)
[<c0378d79>] (load_module) from [<c037974d>] (SyS_finit_module+0x59/0x84)
[<c037974d>] (SyS_finit_module) from [<c030e981>] (ret_fast_syscall+0x1/0x18)
---[ end trace e1b64ced7a89adcc ]---
------------[ cut here ]------------
WARNING: CPU: 14 PID: 2265 at .../kernel/trace/ftrace.c:1979 ftrace_bug+0x1b1/0x234()
...
Hardware name: LSI Axxia AXM55XX
[<c0314a49>] (unwind_backtrace) from [<c03115e9>] (show_stack+0x11/0x14)
[<c03115e9>] (show_stack) from [<c0519f51>] (dump_stack+0x81/0xa8)
[<c0519f51>] (dump_stack) from [<c032185d>] (warn_slowpath_common+0x69/0x90)
[<c032185d>] (warn_slowpath_common) from [<c03218f3>] (warn_slowpath_null+0x17/0x1c)
[<c03218f3>] (warn_slowpath_null) from [<c038e87d>] (ftrace_bug+0x1b1/0x234)
[<c038e87d>] (ftrace_bug) from [<c038ebd5>] (ftrace_process_locs+0x285/0x3e8)
[<c038ebd5>] (ftrace_process_locs) from [<c0378d79>] (load_module+0x11e9/0x1a44)
[<c0378d79>] (load_module) from [<c037974d>] (SyS_finit_module+0x59/0x84)
[<c037974d>] (SyS_finit_module) from [<c030e981>] (ret_fast_syscall+0x1/0x18)
---[ end trace e1b64ced7a89adcd ]---

ftrace failed to modify [<e9ef7006>] 0xe9ef7006
actual: 02:f0:3b:fa
ftrace record flags: 0
(0) expected tramp: c0314265

Signed-off-by Alexander Sverdlin <[email protected]>

Signed-off-by Russell King <[email protected]>

Signed-off-by Florian Fainelli <[email protected]>

---
 arch/arm/include/asm/ftrace.h |  3 +++
 arch/arm/include/asm/module.h |  1 +
 arch/arm/kernel/ftrace.c      | 46 +++++++++++++++++++++++++++++------
 arch/arm/kernel/module-plts.c | 44 ++++++++++++++++++++++++++++++---
 4 files changed, 82 insertions(+), 12 deletions(-)

arch/arm/include/asm/ftrace.h +3 -0

index 48ec1d0337da..a4dbac07e4ef 100644
@@ -15,6 +15,9 @@ extern void __gnu_mcount_nc(void);
 
 #ifdef CONFIG_DYNAMIC_FTRACE
 struct dyn_arch_ftrace {
+#ifdef CONFIG_ARM_MODULE_PLTS
+	struct module *mod;
+#endif
 };
 
 static inline unsigned long ftrace_call_adjust(unsigned long addr)

arch/arm/include/asm/module.h +1 -0

index 09b9ad55b83d..cfffae67c04e 100644
@@ -30,6 +30,7 @@ struct plt_entries {
 
 struct mod_plt_sec {
 	struct elf32_shdr	*plt;
+	struct plt_entries	*plt_ent;
 	int			plt_count;
 };

arch/arm/kernel/ftrace.c +38 -8

92 lines not on this page · raw message

arch/arm/kernel/module-plts.c +40 -4

85 lines not on this page · raw message

Signature · 1 line

2.25.1

Alexander Sverdlin

2021-09-22 06:53 UTC #4 lore raw

Re: [PATCH stable 5.10 3/3] ARM: 9079/1: ftrace: Add MODULE_PLTS support

Hello Florian,

Quoted 6 lines · Florian Fainelli

From: Alex Sverdlin <[email protected]>
commit 79f32b221b18c15a98507b101ef4beb52444cc6f upstream
Teach ftrace_make_call() and ftrace_make_nop() about PLTs. Teach PLT code about FTRACE and all its callbacks.

sorry for inconvenience, but I'd propose to add 6fa630bf473827ae "ARM: 9098/1: ftrace: MODULE_PLT: Fix build problem without DYNAMIC_FTRACE" to all series on this topic, because of the below chunk which might lead to build issues on some exotic configurations.

Link https://lists.01.org/hyperkitty/list/[email protected]/thread/ZUVCQBHDMFVR7CCB7JPESLJEWERZDJ3T/

Quoted 16 lines

arch/arm/kernel/module-plts.c +7 -0

@@ -20,19 +21,52 @@
 						    (PLT_ENT_STRIDE - 8))
 #endif
 
+static const u32 fixed_plts[] = {
+#ifdef CONFIG_FUNCTION_TRACER
+	FTRACE_ADDR,
+	MCOUNT_ADDR,
+#endif
+};
+
 static bool in_init(const struct module *mod, unsigned long loc)
 {
 	return loc - (u32)mod->init_layout.base < mod->init_layout.size;

Signature · 2 lines

Best regards,
Alexander Sverdlin.

Florian Fainelli

author

2021-09-22 16:12 UTC #5 lore raw

Re: [PATCH stable 5.10 3/3] ARM: 9079/1: ftrace: Add MODULE_PLTS support

Hi Alex,

Quoted 10 lines · Alexander Sverdlin

Hello Florian,
Quoted 6 lines · Florian Fainelli
From: Alex Sverdlin <[email protected]>
commit 79f32b221b18c15a98507b101ef4beb52444cc6f upstream
Teach ftrace_make_call() and ftrace_make_nop() about PLTs. Teach PLT code about FTRACE and all its callbacks.

Quoted 6 lines

sorry for inconvenience, but I'd propose to add 6fa630bf473827ae "ARM: 9098/1: ftrace: MODULE_PLT: Fix build problem without DYNAMIC_FTRACE" to all series on this topic, because of the below chunk which might lead to build issues on some exotic configurations.
Link https://lists.01.org/hyperkitty/list/[email protected]/thread/ZUVCQBHDMFVR7CCB7JPESLJEWERZDJ3T/

Good point, missed that one, I will add it to the stable submission and resend, thanks!

Signature · 1 line

Florian