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Peter Collingbourne 590e5e5ec0 hwasan: Untag unwound stack frames by wrapping personality functions.
One problem with untagging memory in landing pads is that it only works
correctly if the function that catches the exception is instrumented.
If the function is uninstrumented, we have no opportunity to untag the
memory.

To address this, replace landing pad instrumentation with personality function
wrapping. Each function with an instrumented stack has its personality function
replaced with a wrapper provided by the runtime. Functions that did not have
a personality function to begin with also get wrappers if they may be unwound
past. As the unwinder calls personality functions during stack unwinding,
the original personality function is called and the function's stack frame is
untagged by the wrapper if the personality function instructs the unwinder
to keep unwinding. If unwinding stops at a landing pad, the function is
still responsible for untagging its stack frame if it resumes unwinding.

The old landing pad mechanism is preserved for compatibility with old runtimes.

Differential Revision: https://reviews.llvm.org/D66377

llvm-svn: 369721
2019-08-23 01:28:44 +00:00

40 lines
1.4 KiB
LLVM

; RUN: opt < %s -mtriple aarch64-linux-android29 -hwasan -S | FileCheck %s --check-prefixes=COMMON,LP,ARM
; RUN: opt < %s -mtriple x86_64-linux -hwasan-instrument-landing-pads -hwasan -S | FileCheck %s --check-prefixes=COMMON,LP,X86
; RUN: opt < %s -mtriple aarch64-linux-android30 -hwasan -S | FileCheck %s --check-prefixes=COMMON,NOLP
target datalayout = "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128"
target triple = "aarch64-unknown-linux-android"
define i32 @f() local_unnamed_addr sanitize_hwaddress personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) {
entry:
invoke void @g()
to label %return unwind label %lpad
lpad:
; COMMON: landingpad { i8*, i32 }
; COMMON-NEXT: catch i8* null
%0 = landingpad { i8*, i32 }
catch i8* null
; NOLP-NOT: call void @__hwasan_handle_vfork
; LP-NEXT: %[[X:[^ ]*]] = call i64 @llvm.read_register.i64(metadata ![[META:[^ ]*]])
; LP-NEXT: call void @__hwasan_handle_vfork(i64 %[[X]])
%1 = extractvalue { i8*, i32 } %0, 0
%2 = tail call i8* @__cxa_begin_catch(i8* %1)
tail call void @__cxa_end_catch()
br label %return
return:
%retval.0 = phi i32 [ 1, %lpad ], [ 0, %entry ]
ret i32 %retval.0
}
declare void @g() local_unnamed_addr
declare i32 @__gxx_personality_v0(...)
declare i8* @__cxa_begin_catch(i8*) local_unnamed_addr
declare void @__cxa_end_catch() local_unnamed_addr
; ARM: ![[META]] = !{!"sp"}
; X86: ![[META]] = !{!"rsp"}