2020-04-24 20:51:43

by Josh Poimboeuf

Subject: [PATCH] samples/ftrace: Fix asm function ELF annotations

Enable objtool coverage for the sample ftrace modules by adding ELF
annotations to the asm trampoline functions.

samples/ftrace/ftrace-direct.o: warning: objtool: .text+0x0: unreachable instruction
samples/ftrace/ftrace-direct-modify.o: warning: objtool: .text+0x0: unreachable instruction
samples/ftrace/ftrace-direct-too.o: warning: objtool: .text+0x0: unreachable instruction

Reported-by: Randy Dunlap <[email protected]>
Signed-off-by: Josh Poimboeuf <[email protected]>
---
samples/ftrace/ftrace-direct-modify.c | 4 ++++
samples/ftrace/ftrace-direct-too.c | 2 ++
samples/ftrace/ftrace-direct.c | 2 ++
3 files changed, 8 insertions(+)

diff --git a/samples/ftrace/ftrace-direct-modify.c b/samples/ftrace/ftrace-direct-modify.c
index e04229d21475..c13a5bc5095b 100644
--- a/samples/ftrace/ftrace-direct-modify.c
+++ b/samples/ftrace/ftrace-direct-modify.c
@@ -20,18 +20,22 @@ static unsigned long my_ip = (unsigned long)schedule;

asm (
" .pushsection .text, \"ax\", @progbits\n"
+" .type my_tramp1, @function\n"
" my_tramp1:"
" pushq %rbp\n"
" movq %rsp, %rbp\n"
" call my_direct_func1\n"
" leave\n"
+" .size my_tramp1, .-my_tramp1\n"
" ret\n"
+" .type my_tramp2, @function\n"
" my_tramp2:"
" pushq %rbp\n"
" movq %rsp, %rbp\n"
" call my_direct_func2\n"
" leave\n"
" ret\n"
+" .size my_tramp2, .-my_tramp2\n"
" .popsection\n"
);

diff --git a/samples/ftrace/ftrace-direct-too.c b/samples/ftrace/ftrace-direct-too.c
index 27efa5f6ff52..d5c5022be664 100644
--- a/samples/ftrace/ftrace-direct-too.c
+++ b/samples/ftrace/ftrace-direct-too.c
@@ -15,6 +15,7 @@ extern void my_tramp(void *);

asm (
" .pushsection .text, \"ax\", @progbits\n"
+" .type my_tramp, @function\n"
" my_tramp:"
" pushq %rbp\n"
" movq %rsp, %rbp\n"
@@ -27,6 +28,7 @@ asm (
" popq %rdi\n"
" leave\n"
" ret\n"
+" .size my_tramp, .-my_tramp\n"
" .popsection\n"
);

diff --git a/samples/ftrace/ftrace-direct.c b/samples/ftrace/ftrace-direct.c
index a2e3063bd306..63ca06d42c80 100644
--- a/samples/ftrace/ftrace-direct.c
+++ b/samples/ftrace/ftrace-direct.c
@@ -13,6 +13,7 @@ extern void my_tramp(void *);

asm (
" .pushsection .text, \"ax\", @progbits\n"
+" .type my_tramp, @function\n"
" my_tramp:"
" pushq %rbp\n"
" movq %rsp, %rbp\n"
@@ -21,6 +22,7 @@ asm (
" popq %rdi\n"
" leave\n"
" ret\n"
+" .size my_tramp, .-my_tramp\n"
" .popsection\n"
);

--
2.21.1

2020-04-24 23:42:22

by Randy Dunlap

Subject: Re: [PATCH] samples/ftrace: Fix asm function ELF annotations

On 4/24/20 1:49 PM, Josh Poimboeuf wrote:
> Enable objtool coverage for the sample ftrace modules by adding ELF
> annotations to the asm trampoline functions.
>
> samples/ftrace/ftrace-direct.o: warning: objtool: .text+0x0: unreachable instruction
> samples/ftrace/ftrace-direct-modify.o: warning: objtool: .text+0x0: unreachable instruction
> samples/ftrace/ftrace-direct-too.o: warning: objtool: .text+0x0: unreachable instruction
>
> Reported-by: Randy Dunlap <[email protected]>
> Signed-off-by: Josh Poimboeuf <[email protected]>

Acked-by: Randy Dunlap <[email protected]>
Tested-by: Randy Dunlap <[email protected]>

Thanks.

> ---
> samples/ftrace/ftrace-direct-modify.c | 4 ++++
> samples/ftrace/ftrace-direct-too.c | 2 ++
> samples/ftrace/ftrace-direct.c | 2 ++
> 3 files changed, 8 insertions(+)
>
> diff --git a/samples/ftrace/ftrace-direct-modify.c b/samples/ftrace/ftrace-direct-modify.c
> index e04229d21475..c13a5bc5095b 100644
> --- a/samples/ftrace/ftrace-direct-modify.c
> +++ b/samples/ftrace/ftrace-direct-modify.c
> @@ -20,18 +20,22 @@ static unsigned long my_ip = (unsigned long)schedule;
>
> asm (
> " .pushsection .text, \"ax\", @progbits\n"
> +" .type my_tramp1, @function\n"
> " my_tramp1:"
> " pushq %rbp\n"
> " movq %rsp, %rbp\n"
> " call my_direct_func1\n"
> " leave\n"
> +" .size my_tramp1, .-my_tramp1\n"
> " ret\n"
> +" .type my_tramp2, @function\n"
> " my_tramp2:"
> " pushq %rbp\n"
> " movq %rsp, %rbp\n"
> " call my_direct_func2\n"
> " leave\n"
> " ret\n"
> +" .size my_tramp2, .-my_tramp2\n"
> " .popsection\n"
> );
>
> diff --git a/samples/ftrace/ftrace-direct-too.c b/samples/ftrace/ftrace-direct-too.c
> index 27efa5f6ff52..d5c5022be664 100644
> --- a/samples/ftrace/ftrace-direct-too.c
> +++ b/samples/ftrace/ftrace-direct-too.c
> @@ -15,6 +15,7 @@ extern void my_tramp(void *);
>
> asm (
> " .pushsection .text, \"ax\", @progbits\n"
> +" .type my_tramp, @function\n"
> " my_tramp:"
> " pushq %rbp\n"
> " movq %rsp, %rbp\n"
> @@ -27,6 +28,7 @@ asm (
> " popq %rdi\n"
> " leave\n"
> " ret\n"
> +" .size my_tramp, .-my_tramp\n"
> " .popsection\n"
> );
>
> diff --git a/samples/ftrace/ftrace-direct.c b/samples/ftrace/ftrace-direct.c
> index a2e3063bd306..63ca06d42c80 100644
> --- a/samples/ftrace/ftrace-direct.c
> +++ b/samples/ftrace/ftrace-direct.c
> @@ -13,6 +13,7 @@ extern void my_tramp(void *);
>
> asm (
> " .pushsection .text, \"ax\", @progbits\n"
> +" .type my_tramp, @function\n"
> " my_tramp:"
> " pushq %rbp\n"
> " movq %rsp, %rbp\n"
> @@ -21,6 +22,7 @@ asm (
> " popq %rdi\n"
> " leave\n"
> " ret\n"
> +" .size my_tramp, .-my_tramp\n"
> " .popsection\n"
> );
>
>


--
~Randy