[PATCH 2/4] ntdll: Keep track of syscall frame unix return addresses.
Jinoh Kang
jinoh.kang.kr at gmail.com
Wed Feb 9 10:34:15 CST 2022
On 2/8/22 04:05, Rémi Bernon wrote:
> For pthread_exit unwinding purposes, as libunwind needs to retrieve %rip
> and we don't want to let it unwind the PE frames, we need to keep track
> of a unix-only return address chain.
>
> Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=52213
> Signed-off-by: Rémi Bernon <rbernon at codeweavers.com>
> ---
> dlls/ntdll/unix/signal_i386.c | 7 +++++--
> dlls/ntdll/unix/signal_x86_64.c | 5 ++++-
> 2 files changed, 9 insertions(+), 3 deletions(-)
>
> diff --git a/dlls/ntdll/unix/signal_i386.c b/dlls/ntdll/unix/signal_i386.c
> index 0e3b1daf51a..d98a3b1d4bb 100644
> --- a/dlls/ntdll/unix/signal_i386.c
> +++ b/dlls/ntdll/unix/signal_i386.c
> @@ -463,9 +463,10 @@ struct syscall_frame
> * 32-bit mode, but some processors fault if they're not in writable memory.
> */
> DECLSPEC_ALIGN(64) XSTATE xstate; /* 240 */
> + DWORD unwind_eip; /* 380 */
> };
>
> -C_ASSERT( sizeof(struct syscall_frame) == 0x380 );
> +C_ASSERT( sizeof(struct syscall_frame) == 0x3c0 );
>
> struct x86_thread_data
> {
> @@ -2432,7 +2433,7 @@ __ASM_GLOBAL_FUNC( signal_start_thread,
> "movl 0x1f8(%ecx),%eax\n\t" /* x86_thread_data()->syscall_frame */
> "orl %eax,%eax\n\t"
> "jnz 1f\n\t"
> - "leal -0x380(%esp),%eax\n\t" /* sizeof(struct syscall_frame) */
> + "leal -0x3c0(%esp),%eax\n\t" /* sizeof(struct syscall_frame) */
> "andl $~63,%eax\n\t"
> "movl %eax,0x1f8(%ecx)\n" /* x86_thread_data()->syscall_frame */
> "1:\tmovl %eax,%esp\n\t"
> @@ -2591,6 +2592,8 @@ __ASM_GLOBAL_FUNC( __wine_syscall_dispatcher,
> "6:\tmovl $0xc000000d,%eax\n\t" /* STATUS_INVALID_PARAMETER */
> "jmp 5b\n"
> __ASM_NAME("__wine_syscall_dispatcher_return") ":\n\t"
> + "movl 0(%esp),%eax\n\t"
> + "movl %eax,0x380(%esp)\n\t" /* frame->unwind_eip */
We can't unwind to the caller without also saving the caller's nonvolatile registers.
Also, KeUserModeCallback is one of the callers of __wine_syscall_dispatcher_return, and returning to it would not be useful since it is usually called from PE modules anyway.
Maybe just use prev_frame directly, and set unwind_eip to an hardcoded address?
(Speaking of which, we could use .cfi_val_encoded_addr here, but it's a GNU-only extension AFAIK.)
> "movl 8(%esp),%eax\n\t"
> "movl 4(%esp),%esp\n\t"
> "jmp 5b" )
> diff --git a/dlls/ntdll/unix/signal_x86_64.c b/dlls/ntdll/unix/signal_x86_64.c
> index da89b958665..f8cddd15569 100644
> --- a/dlls/ntdll/unix/signal_x86_64.c
> +++ b/dlls/ntdll/unix/signal_x86_64.c
> @@ -349,7 +349,8 @@ struct syscall_frame
> struct syscall_frame *prev_frame; /* 00a0 */
> SYSTEM_SERVICE_TABLE *syscall_table; /* 00a8 */
> DWORD syscall_flags; /* 00b0 */
> - DWORD align[3]; /* 00b4 */
> + DWORD align; /* 00b4 */
> + ULONG64 unwind_rip; /* 00b8 */
> XMM_SAVE_AREA32 xsave; /* 00c0 */
> DECLSPEC_ALIGN(64) XSTATE xstate; /* 02c0 */
> };
> @@ -3278,6 +3279,8 @@ __ASM_GLOBAL_FUNC( __wine_syscall_dispatcher,
> "5:\tmovl $0xc000000d,%edx\n\t" /* STATUS_INVALID_PARAMETER */
> "movq %rsp,%rcx\n"
> __ASM_NAME("__wine_syscall_dispatcher_return") ":\n\t"
> + "movq 0(%rsp),%r14\n\t"
> + "movq %r14,0xb8(%rcx)\n\t" /* frame->unwind_rip */
Ditto.
> "movl 0xb0(%rcx),%r14d\n\t" /* frame->syscall_flags */
> "movq %rdx,%rax\n\t"
> "jmp 2b" )
--
Sincerely,
Jinoh Kang
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