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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: 3c88ee194c ("x86: ptrace: Add function argument access API")
Signed-off-by: Vamshi K Sthambamkadi <vamshi.k.sthambamkadi@gmail.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/20200828113242.GA1424@cosmos
zero-sugar-mainline-defconfig
Vamshi K Sthambamkadi 2020-08-28 17:02:46 +05:30 committed by Borislav Petkov
parent ccae0f36d5
commit 2356bb4b82
1 changed files with 1 additions and 1 deletions
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2
arch/x86/include/asm/ptrace.h
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@ -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),