The branch main has been updated by trasz:
URL:
https://cgit.FreeBSD.org/src/commit/?id=023bff799098cac28732f2800c967f0248d2eb47
commit 023bff799098cac28732f2800c967f0248d2eb47
Author: Edward Tomasz Napierala <tr...@freebsd.org>
AuthorDate: 2021-05-04 13:11:01 +0000
Commit: Edward Tomasz Napierala <tr...@freebsd.org>
CommitDate: 2021-05-04 14:21:06 +0000
linux(4): fix ptrace(2) to properly handle orig_rax
This fixes strace(1) erroneously reporting return values
as "Function not implemented", combined with reporting the binary
ABI as X32.
Very similar code in linux_ptrace_getregs() is left as it is - it's
probably wrong too, but I don't have a way to test it.
Sponsored By: EPSRC
Differential Revision: https://reviews.freebsd.org/D29927
---
sys/amd64/linux/linux_ptrace.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/sys/amd64/linux/linux_ptrace.c b/sys/amd64/linux/linux_ptrace.c
index 76ad9b1e25c4..43ecd8892e0f 100644
--- a/sys/amd64/linux/linux_ptrace.c
+++ b/sys/amd64/linux/linux_ptrace.c
@@ -506,18 +506,18 @@ linux_ptrace_getregset_prstatus(struct thread *td, pid_t
pid, l_ulong data)
}
if (lwpinfo.pl_flags & PL_FLAG_SCE) {
/*
- * The strace(1) utility depends on RAX being set to -ENOSYS
- * on syscall entry; otherwise it loops printing those:
- *
- * [ Process PID=928 runs in 64 bit mode. ]
- * [ Process PID=928 runs in x32 mode. ]
+ * Undo the mangling done in exception.S:fast_syscall_common().
*/
- l_regset.rax = -38; /* -ENOSYS */
+ l_regset.r10 = l_regset.rcx;
+ }
+ if (lwpinfo.pl_flags & (PL_FLAG_SCE | PL_FLAG_SCX)) {
/*
- * Undo the mangling done in exception.S:fast_syscall_common().
+ * In Linux, the syscall number - passed to the syscall
+ * as rax - is preserved in orig_rax; rax gets overwritten
+ * with syscall return value.
*/
- l_regset.r10 = l_regset.rcx;
+ l_regset.orig_rax = lwpinfo.pl_syscall_code;
}
len = MIN(iov.iov_len, sizeof(l_regset));
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