Date: Thu, 19 Sep 2024 09:53:35 GMT From: Mark Johnston <markj@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: 9aabab09c4e1 - main - dtrace/amd64: Fix probe argument fetching Message-ID: <202409190953.48J9rZw2075295@gitrepo.freebsd.org>
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The branch main has been updated by markj: URL: https://cgit.FreeBSD.org/src/commit/?id=9aabab09c4e163fa8187b265d6836d822516b1c9 commit 9aabab09c4e163fa8187b265d6836d822516b1c9 Author: Mark Johnston <markj@FreeBSD.org> AuthorDate: 2024-09-19 09:21:38 +0000 Commit: Mark Johnston <markj@FreeBSD.org> CommitDate: 2024-09-19 09:21:38 +0000 dtrace/amd64: Fix probe argument fetching dtrace_getarg() previously walked the call stack looking for a frame matching the dtrace_invop_callsite symbol, in order to look for a trapframe corresponding to an invop (i.e., FBT or kinst) probe. Commit 3ba8e9dc4a0e broke this in some cases by breaking the expected alignment of the dtrace_invop_callsite symbol. Rather than groveling around the stack to find invop probe arguments, simply use the trapframe reference saved by dtrace_invop(). This is simpler and less fragile. Reported by: avg Reviewed by: avg MFC after: 2 weeks Fixes: 3ba8e9dc4a0e ("dtrace/amd64: Implement emulation of call instructions") Differential Revision: https://reviews.freebsd.org/D46672 --- sys/cddl/dev/dtrace/amd64/dtrace_isa.c | 77 ++++++++++++++-------------------- 1 file changed, 31 insertions(+), 46 deletions(-) diff --git a/sys/cddl/dev/dtrace/amd64/dtrace_isa.c b/sys/cddl/dev/dtrace/amd64/dtrace_isa.c index 9db5a16190db..83d34abbd270 100644 --- a/sys/cddl/dev/dtrace/amd64/dtrace_isa.c +++ b/sys/cddl/dev/dtrace/amd64/dtrace_isa.c @@ -32,6 +32,8 @@ #include <sys/stack.h> #include <sys/pcpu.h> +#include <cddl/dev/dtrace/dtrace_cddl.h> + #include <machine/frame.h> #include <machine/md_var.h> #include <machine/stack.h> @@ -355,6 +357,7 @@ zero: uint64_t dtrace_getarg(int arg, int aframes) { + struct thread *td; uintptr_t val; struct amd64_frame *fp = (struct amd64_frame *)dtrace_getfp(); uintptr_t *stack; @@ -366,57 +369,39 @@ dtrace_getarg(int arg, int aframes) */ int inreg = 5; - for (i = 1; i <= aframes; i++) { - fp = fp->f_frame; - - if (roundup2(fp->f_retaddr, 16) == - (long)dtrace_invop_callsite) { - /* - * In the case of amd64, we will use the pointer to the - * regs structure that was pushed when we took the - * trap. To get this structure, we must increment - * beyond the frame structure, and then again beyond - * the calling RIP stored in dtrace_invop(). If the - * argument that we're seeking is passed on the stack, - * we'll pull the true stack pointer out of the saved - * registers and decrement our argument by the number - * of arguments passed in registers; if the argument - * we're seeking is passed in registers, we can just - * load it directly. - */ - struct trapframe *tf = (struct trapframe *)&fp[1]; - - if (arg <= inreg) { - switch (arg) { - case 0: - stack = (uintptr_t *)&tf->tf_rdi; - break; - case 1: - stack = (uintptr_t *)&tf->tf_rsi; - break; - case 2: - stack = (uintptr_t *)&tf->tf_rdx; - break; - case 3: - stack = (uintptr_t *)&tf->tf_rcx; - break; - case 4: - stack = (uintptr_t *)&tf->tf_r8; - break; - case 5: - stack = (uintptr_t *)&tf->tf_r9; - break; - } - arg = 0; - } else { - stack = (uintptr_t *)(tf->tf_rsp); - arg -= inreg; + /* + * Did we arrive here via dtrace_invop()? We can simply fetch arguments + * from the trap frame if so. + */ + td = curthread; + if (td->t_dtrace_trapframe != NULL) { + struct trapframe *tf = td->t_dtrace_trapframe; + + if (arg <= inreg) { + switch (arg) { + case 0: + return (tf->tf_rdi); + case 1: + return (tf->tf_rsi); + case 2: + return (tf->tf_rdx); + case 3: + return (tf->tf_rcx); + case 4: + return (tf->tf_r8); + case 5: + return (tf->tf_r9); } - goto load; } + arg -= inreg; + stack = (uintptr_t *)tf->tf_rsp; + goto load; } + for (i = 1; i <= aframes; i++) + fp = fp->f_frame; + /* * We know that we did not come through a trap to get into * dtrace_probe() -- the provider simply called dtrace_probe()
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