Skip to content

Commit

Permalink
Cut down on #[cfg] soup in libunwind.rs (#449)
Browse files Browse the repository at this point in the history 
Try to wrangle things with `cfg_if!` since otherwise it's pretty hard to
understand what's going on.
  • Loading branch information
@alexcrichton
alexcrichton authored Oct 25, 2021
1 parent 14837b9 commit 6478345
Showing 1 changed file with 98 additions and 121 deletions.
219 changes: 98 additions & 121 deletions src/backtrace/libunwind.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -146,145 +146,122 @@ mod uw {
extern "C" fn(ctx: *mut _Unwind_Context, arg: *mut c_void) -> _Unwind_Reason_Code;

extern "C" {
// No native _Unwind_Backtrace on iOS
#[cfg(not(all(target_os = "ios", target_arch = "arm")))]
pub fn _Unwind_Backtrace(
trace: _Unwind_Trace_Fn,
trace_argument: *mut c_void,
) -> _Unwind_Reason_Code;
}

cfg_if::cfg_if! {
// available since GCC 4.2.0, should be fine for our purpose
#[cfg(all(
if #[cfg(all(
not(all(target_os = "android", target_arch = "arm")),
not(all(target_os = "freebsd", target_arch = "arm")),
not(all(target_os = "linux", target_arch = "arm")),
not(all(target_os = "horizon", target_arch = "arm"))
))]
pub fn _Unwind_GetIP(ctx: *mut _Unwind_Context) -> libc::uintptr_t;
))] {
extern "C" {
pub fn _Unwind_GetIP(ctx: *mut _Unwind_Context) -> libc::uintptr_t;
pub fn _Unwind_FindEnclosingFunction(pc: *mut c_void) -> *mut c_void;

#[cfg(all(
not(all(target_os = "android", target_arch = "arm")),
not(all(target_os = "freebsd", target_arch = "arm")),
not(all(target_os = "linux", target_arch = "arm"))
))]
pub fn _Unwind_FindEnclosingFunction(pc: *mut c_void) -> *mut c_void;

#[cfg(all(
not(all(target_os = "android", target_arch = "arm")),
not(all(target_os = "freebsd", target_arch = "arm")),
not(all(target_os = "linux", target_arch = "arm")),
not(all(target_os = "linux", target_arch = "s390x"))
))]
// This function is a misnomer: rather than getting this frame's
// Canonical Frame Address (aka the caller frame's SP) it
// returns this frame's SP.
//
// https://github.com/libunwind/libunwind/blob/d32956507cf29d9b1a98a8bce53c78623908f4fe/src/unwind/GetCFA.c#L28-L35
#[link_name = "_Unwind_GetCFA"]
pub fn get_sp(ctx: *mut _Unwind_Context) -> libc::uintptr_t;
}
#[cfg(not(all(target_os = "linux", target_arch = "s390x")))]
// This function is a misnomer: rather than getting this frame's
// Canonical Frame Address (aka the caller frame's SP) it
// returns this frame's SP.
//
// https://github.com/libunwind/libunwind/blob/d32956507cf29d9b1a98a8bce53c78623908f4fe/src/unwind/GetCFA.c#L28-L35
#[link_name = "_Unwind_GetCFA"]
pub fn get_sp(ctx: *mut _Unwind_Context) -> libc::uintptr_t;

// s390x uses a biased CFA value, therefore we need to use
// _Unwind_GetGR to get the stack pointer register (%r15)
// instead of relying on _Unwind_GetCFA.
#[cfg(all(target_os = "linux", target_arch = "s390x"))]
pub unsafe fn get_sp(ctx: *mut _Unwind_Context) -> libc::uintptr_t {
extern "C" {
pub fn _Unwind_GetGR(ctx: *mut _Unwind_Context, index: libc::c_int) -> libc::uintptr_t;
}
_Unwind_GetGR(ctx, 15)
}
}

// On android and arm, the function `_Unwind_GetIP` and a bunch of others
// are macros, so we define functions containing the expansion of the
// macros.
//
// TODO: link to the header file that defines these macros, if you can find
// it. (I, fitzgen, cannot find the header file that some of these macro
// expansions were originally borrowed from.)
#[cfg(any(
all(target_os = "android", target_arch = "arm"),
all(target_os = "freebsd", target_arch = "arm"),
all(target_os = "linux", target_arch = "arm"),
all(target_os = "horizon", target_arch = "arm")
))]
pub use self::arm::*;
#[cfg(any(
all(target_os = "android", target_arch = "arm"),
all(target_os = "freebsd", target_arch = "arm"),
all(target_os = "linux", target_arch = "arm"),
all(target_os = "horizon", target_arch = "arm")
))]
mod arm {
pub use super::*;
#[repr(C)]
enum _Unwind_VRS_Result {
_UVRSR_OK = 0,
_UVRSR_NOT_IMPLEMENTED = 1,
_UVRSR_FAILED = 2,
}
#[repr(C)]
enum _Unwind_VRS_RegClass {
_UVRSC_CORE = 0,
_UVRSC_VFP = 1,
_UVRSC_FPA = 2,
_UVRSC_WMMXD = 3,
_UVRSC_WMMXC = 4,
}
#[repr(C)]
enum _Unwind_VRS_DataRepresentation {
_UVRSD_UINT32 = 0,
_UVRSD_VFPX = 1,
_UVRSD_FPAX = 2,
_UVRSD_UINT64 = 3,
_UVRSD_FLOAT = 4,
_UVRSD_DOUBLE = 5,
}
// s390x uses a biased CFA value, therefore we need to use
// _Unwind_GetGR to get the stack pointer register (%r15)
// instead of relying on _Unwind_GetCFA.
#[cfg(all(target_os = "linux", target_arch = "s390x"))]
pub unsafe fn get_sp(ctx: *mut _Unwind_Context) -> libc::uintptr_t {
extern "C" {
pub fn _Unwind_GetGR(ctx: *mut _Unwind_Context, index: libc::c_int) -> libc::uintptr_t;
}
_Unwind_GetGR(ctx, 15)
}
} else {
// On android and arm, the function `_Unwind_GetIP` and a bunch of
// others are macros, so we define functions containing the
// expansion of the macros.
//
// TODO: link to the header file that defines these macros, if you
// can find it. (I, fitzgen, cannot find the header file that some
// of these macro expansions were originally borrowed from.)
#[repr(C)]
enum _Unwind_VRS_Result {
_UVRSR_OK = 0,
_UVRSR_NOT_IMPLEMENTED = 1,
_UVRSR_FAILED = 2,
}
#[repr(C)]
enum _Unwind_VRS_RegClass {
_UVRSC_CORE = 0,
_UVRSC_VFP = 1,
_UVRSC_FPA = 2,
_UVRSC_WMMXD = 3,
_UVRSC_WMMXC = 4,
}
#[repr(C)]
enum _Unwind_VRS_DataRepresentation {
_UVRSD_UINT32 = 0,
_UVRSD_VFPX = 1,
_UVRSD_FPAX = 2,
_UVRSD_UINT64 = 3,
_UVRSD_FLOAT = 4,
_UVRSD_DOUBLE = 5,
}

type _Unwind_Word = libc::c_uint;
extern "C" {
fn _Unwind_VRS_Get(
ctx: *mut _Unwind_Context,
klass: _Unwind_VRS_RegClass,
word: _Unwind_Word,
repr: _Unwind_VRS_DataRepresentation,
data: *mut c_void,
) -> _Unwind_VRS_Result;
}
type _Unwind_Word = libc::c_uint;
extern "C" {
fn _Unwind_VRS_Get(
ctx: *mut _Unwind_Context,
klass: _Unwind_VRS_RegClass,
word: _Unwind_Word,
repr: _Unwind_VRS_DataRepresentation,
data: *mut c_void,
) -> _Unwind_VRS_Result;
}

pub unsafe fn _Unwind_GetIP(ctx: *mut _Unwind_Context) -> libc::uintptr_t {
let mut val: _Unwind_Word = 0;
let ptr = &mut val as *mut _Unwind_Word;
let _ = _Unwind_VRS_Get(
ctx,
_Unwind_VRS_RegClass::_UVRSC_CORE,
15,
_Unwind_VRS_DataRepresentation::_UVRSD_UINT32,
ptr as *mut c_void,
);
(val & !1) as libc::uintptr_t
}
pub unsafe fn _Unwind_GetIP(ctx: *mut _Unwind_Context) -> libc::uintptr_t {
let mut val: _Unwind_Word = 0;
let ptr = &mut val as *mut _Unwind_Word;
let _ = _Unwind_VRS_Get(
ctx,
_Unwind_VRS_RegClass::_UVRSC_CORE,
15,
_Unwind_VRS_DataRepresentation::_UVRSD_UINT32,
ptr as *mut c_void,
);
(val & !1) as libc::uintptr_t
}

// R13 is the stack pointer on arm.
const SP: _Unwind_Word = 13;
// R13 is the stack pointer on arm.
const SP: _Unwind_Word = 13;

pub unsafe fn get_sp(ctx: *mut _Unwind_Context) -> libc::uintptr_t {
let mut val: _Unwind_Word = 0;
let ptr = &mut val as *mut _Unwind_Word;
let _ = _Unwind_VRS_Get(
ctx,
_Unwind_VRS_RegClass::_UVRSC_CORE,
SP,
_Unwind_VRS_DataRepresentation::_UVRSD_UINT32,
ptr as *mut c_void,
);
val as libc::uintptr_t
}
pub unsafe fn get_sp(ctx: *mut _Unwind_Context) -> libc::uintptr_t {
let mut val: _Unwind_Word = 0;
let ptr = &mut val as *mut _Unwind_Word;
let _ = _Unwind_VRS_Get(
ctx,
_Unwind_VRS_RegClass::_UVRSC_CORE,
SP,
_Unwind_VRS_DataRepresentation::_UVRSD_UINT32,
ptr as *mut c_void,
);
val as libc::uintptr_t
}

// This function also doesn't exist on Android or ARM/Linux, so make it
// a no-op.
pub unsafe fn _Unwind_FindEnclosingFunction(pc: *mut c_void) -> *mut c_void {
pc
// This function also doesn't exist on Android or ARM/Linux, so make it
// a no-op.
pub unsafe fn _Unwind_FindEnclosingFunction(pc: *mut c_void) -> *mut c_void {
pc
}
}
}
}

0 comments on commit 6478345

Please sign in to comment.