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kprobes, x86/ptrace.h: fix regs argument order for i386

PATCH Applied Vamshi K Sthambamkadi 4 participants 4 messages Aug 28, 2020 – Sep 4, 2020

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Vamshi K Sthambamkadi

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#0 lore raw

PATCH 1/1 kprobes, x86/ptrace.h: fix regs argument order for i386

On i386, the order of parameters passed on regs is eax,edx,and ecx (as per regparm(3) calling conventions).

Change the mapping in regs_get_kernel_argument(), so that arg1=ax arg2=dx, and arg3=cx.

Running the selftests testcase kprobes_args_use.tc shows the result as passed.

Signed-off-by Vamshi K Sthambamkadi <[email protected]>
---
 arch/x86/include/asm/ptrace.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
arch/x86/include/asm/ptrace.h +1 -1
index 40aa69d..d8324a2 100644
@@ -327,8 +327,8 @@ static inline unsigned long regs_get_kernel_argument(struct pt_regs *regs,
 	static const unsigned int argument_offs[] = {
 #ifdef __i386__
 		offsetof(struct pt_regs, ax),
-		offsetof(struct pt_regs, cx),
 		offsetof(struct pt_regs, dx),
+		offsetof(struct pt_regs, cx),
 #define NR_REG_ARGUMENTS 3
 #else
 		offsetof(struct pt_regs, di),
Signature · 1 line
2.7.4
Acked-by on v1 1/1
#1 lore raw
Quoted 8 lines · On Fri, 28 Aug 2020 17:02:46 +0530 Vamshi K Sthambamkadi…

On i386, the order of parameters passed on regs is eax,edx,and ecx (as per regparm(3) calling conventions).

Change the mapping in regs_get_kernel_argument(), so that arg1=ax arg2=dx, and arg3=cx.

Running the selftests testcase kprobes_args_use.tc shows the result as passed.

Good catch! BTW, this is for tracing (ftrace kprobe events), so the "tracing/kprobes:" tag is better. Anyway,

Acked-by Masami Hiramatsu <[email protected]>

Thank you,

Quoted 23 lines
Signed-off-by Vamshi K Sthambamkadi <[email protected]>
---
 arch/x86/include/asm/ptrace.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
arch/x86/include/asm/ptrace.h +1 -1
index 40aa69d..d8324a2 100644
@@ -327,8 +327,8 @@ static inline unsigned long regs_get_kernel_argument(struct pt_regs *regs,
 	static const unsigned int argument_offs[] = {
 #ifdef __i386__
 		offsetof(struct pt_regs, ax),
-		offsetof(struct pt_regs, cx),
 		offsetof(struct pt_regs, dx),
+		offsetof(struct pt_regs, cx),
 #define NR_REG_ARGUMENTS 3
 #else
 		offsetof(struct pt_regs, di),
Signature · 1 line
2.7.4
Signature · 1 line
Masami Hiramatsu <[email protected]>
Acked-by on v1 1/1
#2 lore raw
In reply to Vamshi K Sthambamkadi
Quoted 9 lines · Vamshi K Sthambamkadi

On i386, the order of parameters passed on regs is eax,edx,and ecx (as per regparm(3) calling conventions).

Change the mapping in regs_get_kernel_argument(), so that arg1=ax arg2=dx, and arg3=cx.

Running the selftests testcase kprobes_args_use.tc shows the result as passed.

Fixes 3c88ee194c28 ("x86: ptrace: Add function argument access API")
Quoted 1 line
Signed-off-by Vamshi K Sthambamkadi <[email protected]>
Acked-by Peter Zijlstra (Intel) <[email protected]>
Quoted 21 lines
---
 arch/x86/include/asm/ptrace.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
arch/x86/include/asm/ptrace.h +1 -1
index 40aa69d..d8324a2 100644
@@ -327,8 +327,8 @@ static inline unsigned long regs_get_kernel_argument(struct pt_regs *regs,
 	static const unsigned int argument_offs[] = {
 #ifdef __i386__
 		offsetof(struct pt_regs, ax),
-		offsetof(struct pt_regs, cx),
 		offsetof(struct pt_regs, dx),
+		offsetof(struct pt_regs, cx),
 #define NR_REG_ARGUMENTS 3
 #else
 		offsetof(struct pt_regs, di),
Signature · 1 line
2.7.4
merge bot Applied
#3 lore raw

[tip: x86/urgent] tracing/kprobes, x86/ptrace: Fix regs argument order for i386

In reply to Vamshi K Sthambamkadi
The following commit has been merged into the x86/urgent branch of tip:

The following commit has been merged into the x86/urgent branch of tip:

Commit-ID:     2356bb4b8221d7dc8c7beb810418122ed90254c9
Gitweb:        https://git.kernel.org/tip/2356bb4b8221d7dc8c7beb810418122ed90254c9
Author:        Vamshi K Sthambamkadi <[email protected]>
AuthorDate:    Fri, 28 Aug 2020 17:02:46 +05:30
Committer:     Borislav Petkov <[email protected]>
CommitterDate: Fri, 04 Sep 2020 14:40:42 +02:00

tracing/kprobes, x86/ptrace: Fix regs argument order for i386

On i386, the order of parameters passed on regs is eax,edx,and ecx (as per regparm(3) calling conventions).

Change the mapping in regs_get_kernel_argument(), so that arg1=ax arg2=dx, and arg3=cx.

Running the selftests testcase kprobes_args_use.tc shows the result as passed.

Fixes 3c88ee194c28 ("x86: ptrace: Add function argument access API")
Signed-off-by Vamshi K Sthambamkadi <[email protected]>
Signed-off-by Borislav Petkov <[email protected]>
Acked-by Masami Hiramatsu <[email protected]>
Acked-by Peter Zijlstra (Intel) <[email protected]>
Cc <[email protected]>
Link https://lkml.kernel.org/r/20200828113242.GA1424@cosmos open here
---
 arch/x86/include/asm/ptrace.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
arch/x86/include/asm/ptrace.h +1 -1
index 40aa69d..d8324a2 100644
@@ -327,8 +327,8 @@ static inline unsigned long regs_get_kernel_argument(struct pt_regs *regs,
 	static const unsigned int argument_offs[] = {
 #ifdef __i386__
 		offsetof(struct pt_regs, ax),
-		offsetof(struct pt_regs, cx),
 		offsetof(struct pt_regs, dx),
+		offsetof(struct pt_regs, cx),
 #define NR_REG_ARGUMENTS 3
 #else
 		offsetof(struct pt_regs, di),