64 lines
1.7 KiB
Groff
64 lines
1.7 KiB
Groff
diff --git a/arch/x86_64/kernel/entry.S b/arch/x86_64/kernel/entry.S
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index 7c10e90..ab6e44d 100644
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--- a/arch/x86_64/kernel/entry.S
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+++ b/arch/x86_64/kernel/entry.S
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@@ -180,6 +180,10 @@ rff_trace:
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*
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* XXX if we had a free scratch register we could save the RSP into the stack frame
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* and report it properly in ps. Unfortunately we haven't.
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+ *
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+ * When user can change the frames always force IRET. That is because
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+ * it deals with uncanonical addresses better. SYSRET has trouble
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+ * with them due to bugs in both AMD and Intel CPUs.
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*/
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ENTRY(system_call)
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@@ -254,7 +258,10 @@ sysret_signal:
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xorl %esi,%esi # oldset -> arg2
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call ptregscall_common
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1: movl $_TIF_NEED_RESCHED,%edi
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- jmp sysret_check
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+ /* Use IRET because user could have changed frame. This
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+ works because ptregscall_common has called FIXUP_TOP_OF_STACK. */
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+ cli
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+ jmp int_with_check
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badsys:
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movq $-ENOSYS,RAX-ARGOFFSET(%rsp)
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@@ -280,7 +287,8 @@ tracesys:
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call syscall_trace_leave
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RESTORE_TOP_OF_STACK %rbx
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RESTORE_REST
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- jmp ret_from_sys_call
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+ /* Use IRET because user could have changed frame */
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+ jmp int_ret_from_sys_call
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CFI_ENDPROC
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/*
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@@ -408,25 +416,9 @@ ENTRY(stub_execve)
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CFI_ADJUST_CFA_OFFSET -8
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CFI_REGISTER rip, r11
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SAVE_REST
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- movq %r11, %r15
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- CFI_REGISTER rip, r15
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FIXUP_TOP_OF_STACK %r11
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call sys_execve
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- GET_THREAD_INFO(%rcx)
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- bt $TIF_IA32,threadinfo_flags(%rcx)
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- CFI_REMEMBER_STATE
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- jc exec_32bit
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RESTORE_TOP_OF_STACK %r11
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- movq %r15, %r11
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- CFI_REGISTER rip, r11
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- RESTORE_REST
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- pushq %r11
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- CFI_ADJUST_CFA_OFFSET 8
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- CFI_REL_OFFSET rip, 0
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- ret
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-
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-exec_32bit:
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- CFI_RESTORE_STATE
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movq %rax,RAX(%rsp)
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RESTORE_REST
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jmp int_ret_from_sys_call
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