Signed-off-by: Andy Lutomirski <[email protected]>
---
arch/x86/entry/entry_64.S | 2 +-
arch/x86/entry/entry_64_compat.S | 56 +++++++++++++---------------------------
2 files changed, 19 insertions(+), 39 deletions(-)
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 4f8c25eb3437..f9067d610e50 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -582,7 +582,7 @@ retint_kernel:
* At this label, code paths which return to kernel and to user,
* which come from interrupts/exception and from syscalls, merge.
*/
-restore_regs_and_iret:
+GLOBAL(restore_regs_and_iret)
RESTORE_EXTRA_REGS
restore_c_regs_and_iret:
RESTORE_C_REGS
diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S
index 2c2aac577b3c..63ef9fa29002 100644
--- a/arch/x86/entry/entry_64_compat.S
+++ b/arch/x86/entry/entry_64_compat.S
@@ -202,14 +202,17 @@ END(entry_SYSCALL_compat)
ENTRY(entry_INT80_compat)
/*
* Interrupts are off on entry.
- * We do not frame this tiny irq-off block with TRACE_IRQS_OFF/ON,
- * it is too small to ever cause noticeable irq latency.
*/
PARAVIRT_ADJUST_EXCEPTION_FRAME
SWAPGS
- ENABLE_INTERRUPTS(CLBR_NONE)
- /* Zero-extending 32-bit regs, do not remove */
+ /*
+ * User tracing code (ptrace or signal handlers) might assume that
+ * the saved RAX contains a 32-bit number when we're invoking a 32-bit
+ * syscall. Just in case the high bits are nonzero, zero-extend
+ * the syscall number. (This could almost certainly be deleted
+ * with no ill effects.)
+ */
movl %eax, %eax
/* Construct struct pt_regs on stack (iret frame is already on stack) */
@@ -232,42 +235,19 @@ ENTRY(entry_INT80_compat)
pushq %r15 /* pt_regs->r15 */
cld
- orl $TS_COMPAT, ASM_THREAD_INFO(TI_status, %rsp, SIZEOF_PTREGS)
- testl $_TIF_WORK_SYSCALL_ENTRY, ASM_THREAD_INFO(TI_flags, %rsp,
SIZEOF_PTREGS)
- jnz ia32_tracesys
-
-ia32_do_call:
- /* 32-bit syscall -> 64-bit C ABI argument conversion */
- movl %edi, %r8d /* arg5 */
- movl %ebp, %r9d /* arg6 */
- xchg %ecx, %esi /* rsi:arg2, rcx:arg4 */
- movl %ebx, %edi /* arg1 */
- movl %edx, %edx /* arg3 (zero extension) */
- cmpq $(IA32_NR_syscalls-1), %rax
- ja 1f
-
- call *ia32_sys_call_table(, %rax, 8)
- movq %rax, RAX(%rsp)
-1:
- RESTORE_EXTRA_REGS
- jmp int_ret_from_sys_call
-
-ia32_tracesys:
- movq %rsp, %rdi /* &pt_regs -> arg1 */
- call syscall_trace_enter
/*
- * Reload arg registers from stack in case ptrace changed them.
- * Don't reload %eax because syscall_trace_enter() returned
- * the %rax value we should see. But do truncate it to 32 bits.
- * If it's -1 to make us punt the syscall, then (u32)-1 is still
- * an appropriately invalid value.
+ * User mode is traced as though IRQs are on, and the interrupt
+ * gate turned them off.
*/
- movl RCX(%rsp), %ecx
- movl RDX(%rsp), %edx
- movl RSI(%rsp), %esi
- movl RDI(%rsp), %edi
- movl %eax, %eax /* zero extension */
- jmp ia32_do_call
+ TRACE_IRQS_OFF
+
+ movq %rsp, %rdi
+ call do_int80_syscall_32
+
+ /* Go back to user mode. */
+ TRACE_IRQS_ON
+ SWAPGS
+ jmp restore_regs_and_iret
END(entry_INT80_compat)
ALIGN
--
2.4.3
--
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