[compiler-rt] r318261 - [XRay][compiler-rt][x86_64] Align the stack before and after calling handlers
Dean Michael Berris via llvm-commits
llvm-commits at lists.llvm.org
Tue Nov 14 19:35:43 PST 2017
Author: dberris
Date: Tue Nov 14 19:35:42 2017
New Revision: 318261
URL: http://llvm.org/viewvc/llvm-project?rev=318261&view=rev
Log:
[XRay][compiler-rt][x86_64] Align the stack before and after calling handlers
Summary:
This change fixes the XRay trampolines aside from the __xray_CustomEvent
trampoline to align the stack to 16-byte boundaries before calling the
handler. Before this change we've not been explicitly aligning the stack
to 16-byte boundaries, which makes it dangerous when calling handlers
that leave the stack in a state that isn't strictly 16-byte aligned
after calling the handlers.
We add a test that makes sure we can handle these cases appropriately
after the changes, and prevents us from regressing the state moving
forward.
Fixes http://llvm.org/PR35294.
Reviewers: pelikan, pcc
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D40004
Added:
compiler-rt/trunk/test/xray/TestCases/Linux/common-trampoline-alignment.cc
Modified:
compiler-rt/trunk/lib/xray/xray_trampoline_x86_64.S
Modified: compiler-rt/trunk/lib/xray/xray_trampoline_x86_64.S
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/xray/xray_trampoline_x86_64.S?rev=318261&r1=318260&r2=318261&view=diff
==============================================================================
--- compiler-rt/trunk/lib/xray/xray_trampoline_x86_64.S (original)
+++ compiler-rt/trunk/lib/xray/xray_trampoline_x86_64.S Tue Nov 14 19:35:42 2017
@@ -60,6 +60,20 @@
.cfi_def_cfa_offset 8
.endm
+.macro ALIGNED_CALL_RAX
+ // Call the logging handler, after aligning the stack to a 16-byte boundary.
+ // The approach we're taking here uses additional stack space to stash the
+ // stack pointer twice before aligning the pointer to 16-bytes. If the stack
+ // was 8-byte aligned, it will become 16-byte aligned -- when restoring the
+ // pointer, we can always look -8 bytes from the current position to get
+ // either of the values we've stashed in the first place.
+ pushq %rsp
+ pushq (%rsp)
+ andq $-0x10, %rsp
+ callq *%rax
+ movq 8(%rsp), %rsp
+.endm
+
.text
.file "xray_trampoline_x86.S"
@@ -82,7 +96,8 @@ __xray_FunctionEntry:
// The patched function prolog puts its xray_instr_map index into %r10d.
movl %r10d, %edi
xor %esi,%esi
- callq *%rax
+ ALIGNED_CALL_RAX
+
.Ltmp0:
RESTORE_REGISTERS
retq
@@ -113,7 +128,8 @@ __xray_FunctionExit:
movl %r10d, %edi
movl $1, %esi
- callq *%rax
+ ALIGNED_CALL_RAX
+
.Ltmp2:
// Restore the important registers.
movq 48(%rsp), %rbp
@@ -143,7 +159,8 @@ __xray_FunctionTailExit:
movl %r10d, %edi
movl $2, %esi
- callq *%rax
+
+ ALIGNED_CALL_RAX
.Ltmp4:
RESTORE_REGISTERS
@@ -181,7 +198,7 @@ __xray_ArgLoggerEntry:
// 32-bit function ID becomes the first
movl %r10d, %edi
- callq *%rax
+ ALIGNED_CALL_RAX
.Larg1entryFail:
RESTORE_REGISTERS
@@ -207,18 +224,7 @@ __xray_CustomEvent:
testq %rax,%rax
je .LcustomEventCleanup
- // At this point we know that rcx and rdx already has the data, so we just
- // call the logging handler, after aligning the stack to a 16-byte boundary.
- // The approach we're taking here uses additional stack space to stash the
- // stack pointer twice before aligning the pointer to 16-bytes. If the stack
- // was 8-byte aligned, it will become 16-byte aligned -- when restoring the
- // pointer, we can always look -8 bytes from the current position to get
- // either of the values we've stashed in the first place.
- pushq %rsp
- pushq (%rsp)
- andq $-0x10, %rsp
- callq *%rax
- movq 8(%rsp), %rsp
+ ALIGNED_CALL_RAX
.LcustomEventCleanup:
RESTORE_REGISTERS
Added: compiler-rt/trunk/test/xray/TestCases/Linux/common-trampoline-alignment.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/test/xray/TestCases/Linux/common-trampoline-alignment.cc?rev=318261&view=auto
==============================================================================
--- compiler-rt/trunk/test/xray/TestCases/Linux/common-trampoline-alignment.cc (added)
+++ compiler-rt/trunk/test/xray/TestCases/Linux/common-trampoline-alignment.cc Tue Nov 14 19:35:42 2017
@@ -0,0 +1,57 @@
+// Make sure that we're aligning the stack properly to support handlers that
+// expect 16-byte alignment of the stack.
+//
+// RUN: %clangxx_xray -std=c++11 %s -o %t
+// RUN: XRAY_OPTIONS="patch_premain=false verbosity=1 xray_naive_log=false" \
+// RUN: %run %t 2>&1
+// REQUIRES: x86_64-linux
+// REQUIRES: built-in-llvm-tree
+#include "xray/xray_interface.h"
+#include <stdio.h>
+#include <xmmintrin.h>
+
+[[clang::xray_never_instrument]] __attribute__((weak)) __m128 f(__m128 *i) {
+ return *i;
+}
+
+[[clang::xray_always_instrument]] __attribute__((noinline)) void noarg() {
+ __m128 v = {};
+ f(&v);
+}
+
+[[ clang::xray_always_instrument, clang::xray_log_args(1) ]]
+__attribute__((noinline)) void arg1(int) {
+ __m128 v = {};
+ f(&v);
+}
+
+[[clang::xray_always_instrument]] __attribute__((noinline))
+void no_alignment() {}
+
+[[clang::xray_never_instrument]] void noarg_handler(int32_t,
+ XRayEntryType) {
+ printf("noarg handler called\n");
+ __m128 v = {};
+ f(&v);
+}
+
+[[clang::xray_never_instrument]] void arg1_handler(int32_t, XRayEntryType,
+ uint64_t) {
+ printf("arg1 handler called\n");
+ __m128 v = {};
+ f(&v);
+}
+
+int main(int argc, char *argv[]) {
+ __xray_set_handler(noarg_handler);
+ __xray_set_handler_arg1(arg1_handler);
+ __xray_patch();
+ noarg(); // CHECK: noarg handler called
+ arg1(argc); // CHECK: arg1 handler called
+ no_alignment();
+ __xray_unpatch();
+ __xray_remove_handler();
+ __xray_remove_handler_arg1();
+ noarg();
+ arg1(argc);
+}
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