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Update libunwind to v1.5.0
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nongnu libunwind, not LLVM libunwind, so this only affects Linux and
FreeBSD
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@ararslan
ararslan committed Oct 24, 2021
1 parent 74424d0 commit ee01d21
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Showing 4 changed files with 155 additions and 123 deletions.
4 changes: 2 additions & 2 deletions deps/Versions.make
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Original file line number Diff line number Diff line change
Expand Up @@ -104,9 +104,9 @@ LIBSUITESPARSE_VER := 5.10.1
LIBSUITESPARSE_JLL_NAME := SuiteSparse

# unwind
UNWIND_VER := 1.3.2
UNWIND_VER := 1.5.0
UNWIND_JLL_NAME := LibUnwind
UNWIND_JLL_VER := 1.3.2+4
UNWIND_JLL_VER := 1.5.0+0

# zlib
ZLIB_VER := 1.2.11
Expand Down
163 changes: 69 additions & 94 deletions deps/patches/libunwind-cfa-rsp.patch
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Original file line number Diff line number Diff line change
@@ -1,42 +1,54 @@
commit c71298423c26b2143dc6f6ce554ec910ed882f8a
Author: Keno Fischer <[email protected]>
Date: Sat Feb 6 18:13:16 2021 -0500
From 8c8c78e2db09c5dc66ad0188a088b1664483a13f Mon Sep 17 00:00:00 2001
From: Keno Fischer <[email protected]>
Date: Sun, 29 Aug 2021 11:07:54 -0700
Subject: [PATCH] x86_64: Stop aliasing RSP and CFA

x86_64: Stop aliasing RSP and CFA

RSP and CFA are different concepts. RSP refers to the physical
register, CFA is a virtual register that serves as the base
address for various other saved registers. It is true that
in many frames these are set to alias, however this is not
a requirement. For example, a function that performs a stack
switch would likely change the rsp in the middle of the function,
but would keep the CFA at the original RSP such that saved registers
may be appropriately recovered.

We are seeing incorrect unwinds in the Julia runtime when running
julia under rr. This is because injects code (with correct CFI)
that performs just such a stack switch [1]. GDB manages to unwind
this correctly, but libunwind incorrectly sets the rsp to the CFA
address, causing a misunwind.

Tested on x86_64, patches for other architectures are ported, but
not tested.

[1] https://github.com/rr-debugger/rr/blob/469c22059a4a1798d33a8a224457faf22b2c178c/src/preload/syscall_hook.S#L454
RSP and CFA are different concepts. RSP refers to the physical
register, CFA is a virtual register that serves as the base
address for various other saved registers. It is true that
in many frames these are set to alias, however this is not
a requirement. For example, a function that performs a stack
switch would likely change the rsp in the middle of the function,
but would keep the CFA at the original RSP such that saved registers
may be appropriately recovered.

We are seeing incorrect unwinds in the Julia runtime when running
julia under rr. This is because injects code (with correct CFI)
that performs just such a stack switch [1]. GDB manages to unwind
this correctly, but libunwind incorrectly sets the rsp to the CFA
address, causing a misunwind.

Tested on x86_64, patches for other architectures are ported, but
not tested.

[1] https://github.com/rr-debugger/rr/blob/469c22059a4a1798d33a8a224457faf22b2c178c/src/preload/syscall_hook.S#L454
---
include/dwarf.h | 3 +-
include/libunwind_i.h | 4 ++
include/tdep-x86/dwarf-config.h | 2 -
include/tdep-x86/libunwind_i.h | 73 ++++++++++++---------------------
src/dwarf/Gparser.c | 15 +++++--
src/x86/Gos-freebsd.c | 1 +
src/x86/Gregs.c | 2 +-
src/x86/Gstep.c | 4 +-
src/x86_64/Gos-freebsd.c | 1 +
src/x86_64/Gregs.c | 2 +-
src/x86_64/Gstep.c | 2 +-
11 files changed, 52 insertions(+), 57 deletions(-)

diff --git a/include/dwarf.h b/include/dwarf.h
index fab93c61..b845e2eb 100644
index 175c419bb..23ff4c4f6 100644
--- a/include/dwarf.h
+++ b/include/dwarf.h
@@ -227,6 +227,7 @@ typedef enum
@@ -231,6 +231,7 @@ typedef enum
DWARF_WHERE_REG, /* register saved in another register */
DWARF_WHERE_EXPR, /* register saved */
DWARF_WHERE_VAL_EXPR, /* register has computed value */
+ DWARF_WHERE_CFA, /* register is set to the computed cfa value */
}
dwarf_where_t;

@@ -309,7 +310,7 @@ typedef struct dwarf_cursor
@@ -313,7 +314,7 @@ typedef struct dwarf_cursor
void *as_arg; /* argument to address-space callbacks */
unw_addr_space_t as; /* reference to per-address-space info */

Expand All @@ -46,10 +58,10 @@ index fab93c61..b845e2eb 100644
unw_word_t args_size; /* size of arguments */
unw_word_t eh_args[UNW_TDEP_NUM_EH_REGS];
diff --git a/include/libunwind_i.h b/include/libunwind_i.h
index 36cf7a14..dcec1683 100644
index fea5c2607..6c7dda9a8 100644
--- a/include/libunwind_i.h
+++ b/include/libunwind_i.h
@@ -351,6 +351,10 @@ static inline void invalidate_edi (struct elf_dyn_info *edi)
@@ -346,6 +346,10 @@ static inline void invalidate_edi (struct elf_dyn_info *edi)

#include "tdep/libunwind_i.h"

Expand All @@ -61,7 +73,7 @@ index 36cf7a14..dcec1683 100644
# define tdep_get_func_addr(as,addr,v) (*(v) = addr, 0)
#endif
diff --git a/include/tdep-x86/dwarf-config.h b/include/tdep-x86/dwarf-config.h
index f76f9c1c..11398e4e 100644
index f76f9c1c4..11398e4e6 100644
--- a/include/tdep-x86/dwarf-config.h
+++ b/include/tdep-x86/dwarf-config.h
@@ -43,9 +43,7 @@ WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
Expand All @@ -75,21 +87,19 @@ index f76f9c1c..11398e4e 100644
dwarf_loc_t;

diff --git a/include/tdep-x86/libunwind_i.h b/include/tdep-x86/libunwind_i.h
index 5231189a..1b59fe34 100644
index d4c5ccdb1..ad4edc2f5 100644
--- a/include/tdep-x86/libunwind_i.h
+++ b/include/tdep-x86/libunwind_i.h
@@ -88,14 +88,28 @@ dwarf_get_uc(const struct dwarf_cursor *cursor)
@@ -84,15 +84,26 @@ dwarf_get_uc(const struct dwarf_cursor *cursor)
}

#define DWARF_GET_LOC(l) ((l).val)

-#ifdef UNW_LOCAL_ONLY
+
+#define DWARF_GET_LOC(l) ((l).val)
+# define DWARF_LOC_TYPE_MEM (0 << 0)
+# define DWARF_LOC_TYPE_FP (1 << 0)
+# define DWARF_LOC_TYPE_REG (1 << 1)
+# define DWARF_LOC_TYPE_VAL (1 << 2)
+

-#ifdef UNW_LOCAL_ONLY
+# define DWARF_IS_REG_LOC(l) (((l).type & DWARF_LOC_TYPE_REG) != 0)
+# define DWARF_IS_FP_LOC(l) (((l).type & DWARF_LOC_TYPE_FP) != 0)
+# define DWARF_IS_MEM_LOC(l) ((l).type == DWARF_LOC_TYPE_MEM)
Expand All @@ -112,7 +122,7 @@ index 5231189a..1b59fe34 100644
# define DWARF_FPREG_LOC(c,r) (DWARF_LOC((unw_word_t) \
tdep_uc_addr(dwarf_get_uc(c), (r)), 0))

@@ -117,35 +131,8 @@ dwarf_putfp (struct dwarf_cursor *c, dwarf_loc_t loc, unw_fpreg_t val)
@@ -114,35 +125,8 @@ dwarf_putfp (struct dwarf_cursor *c, dwarf_loc_t loc, unw_fpreg_t val)
return 0;
}

Expand Down Expand Up @@ -148,7 +158,7 @@ index 5231189a..1b59fe34 100644
# define DWARF_FPREG_LOC(c,r) DWARF_LOC((r), (DWARF_LOC_TYPE_REG \
| DWARF_LOC_TYPE_FP))

@@ -195,38 +182,33 @@ dwarf_putfp (struct dwarf_cursor *c, dwarf_loc_t loc, unw_fpreg_t val)
@@ -192,38 +176,33 @@ dwarf_putfp (struct dwarf_cursor *c, dwarf_loc_t loc, unw_fpreg_t val)
1, c->as_arg);
}

Expand Down Expand Up @@ -195,7 +205,7 @@ index 5231189a..1b59fe34 100644
if (DWARF_IS_REG_LOC (loc))
return (*c->as->acc.access_reg) (c->as, DWARF_GET_LOC (loc), &val,
1, c->as_arg);
@@ -235,7 +217,9 @@ dwarf_put (struct dwarf_cursor *c, dwarf_loc_t loc, unw_word_t val)
@@ -232,7 +211,9 @@ dwarf_put (struct dwarf_cursor *c, dwarf_loc_t loc, unw_word_t val)
1, c->as_arg);
}

Expand All @@ -207,18 +217,10 @@ index 5231189a..1b59fe34 100644
#define tdep_getcontext_trace unw_getcontext
#define tdep_init_done UNW_OBJ(init_done)
diff --git a/src/dwarf/Gparser.c b/src/dwarf/Gparser.c
index 7d255aee..b1308d3c 100644
index da170d4b3..70a62c505 100644
--- a/src/dwarf/Gparser.c
+++ b/src/dwarf/Gparser.c
@@ -28,6 +28,7 @@ WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
#include <stddef.h>
#include <limits.h>

+
#define alloc_reg_state() (mempool_alloc (&dwarf_reg_state_pool))
#define free_reg_state(rs) (mempool_free (&dwarf_reg_state_pool, rs))

@@ -501,6 +502,9 @@ setup_fde (struct dwarf_cursor *c, dwarf_state_record_t *sr)
@@ -508,6 +508,9 @@ setup_fde (struct dwarf_cursor *c, dwarf_state_record_t *sr)
for (i = 0; i < DWARF_NUM_PRESERVED_REGS + 2; ++i)
set_reg (sr, i, DWARF_WHERE_SAME, 0);

Expand All @@ -228,7 +230,7 @@ index 7d255aee..b1308d3c 100644
struct dwarf_cie_info *dci = c->pi.unwind_info;
sr->rs_current.ret_addr_column = dci->ret_addr_column;
unw_word_t addr = dci->cie_instr_start;
@@ -785,14 +789,14 @@ apply_reg_state (struct dwarf_cursor *c, struct dwarf_reg_state *rs)
@@ -792,14 +795,14 @@ apply_reg_state (struct dwarf_cursor *c, struct dwarf_reg_state *rs)
/* As a special-case, if the stack-pointer is the CFA and the
stack-pointer wasn't saved, popping the CFA implicitly pops
the stack-pointer as well. */
Expand All @@ -247,7 +249,7 @@ index 7d255aee..b1308d3c 100644
return ret;
}
cfa += rs->reg.val[DWARF_CFA_OFF_COLUMN];
@@ -826,6 +830,10 @@ apply_reg_state (struct dwarf_cursor *c, struct dwarf_reg_state *rs)
@@ -836,6 +839,10 @@ apply_reg_state (struct dwarf_cursor *c, struct dwarf_reg_state *rs)
case DWARF_WHERE_SAME:
break;

Expand All @@ -259,7 +261,7 @@ index 7d255aee..b1308d3c 100644
new_loc[i] = DWARF_MEM_LOC (c, cfa + rs->reg.val[i]);
break;
diff --git a/src/x86/Gos-freebsd.c b/src/x86/Gos-freebsd.c
index 7dd01404..1b251d02 100644
index 7dd014046..1b251d027 100644
--- a/src/x86/Gos-freebsd.c
+++ b/src/x86/Gos-freebsd.c
@@ -138,6 +138,7 @@ x86_handle_signal_frame (unw_cursor_t *cursor)
Expand All @@ -271,7 +273,7 @@ index 7dd01404..1b251d02 100644
c->dwarf.cfa += 4;
c->dwarf.use_prev_instr = 1;
diff --git a/src/x86/Gregs.c b/src/x86/Gregs.c
index 4a959261..9446d6c6 100644
index 4a9592617..9446d6c62 100644
--- a/src/x86/Gregs.c
+++ b/src/x86/Gregs.c
@@ -53,7 +53,6 @@ tdep_access_reg (struct cursor *c, unw_regnum_t reg, unw_word_t *valp,
Expand All @@ -291,7 +293,7 @@ index 4a959261..9446d6c6 100644
case UNW_X86_ESI: loc = c->dwarf.loc[ESI]; break;
case UNW_X86_EDI: loc = c->dwarf.loc[EDI]; break;
diff --git a/src/x86/Gstep.c b/src/x86/Gstep.c
index 129b739a..061dcbaa 100644
index 129b739a3..061dcbaaa 100644
--- a/src/x86/Gstep.c
+++ b/src/x86/Gstep.c
@@ -47,7 +47,7 @@ unw_step (unw_cursor_t *cursor)
Expand Down Expand Up @@ -319,35 +321,8 @@ index 129b739a..061dcbaa 100644
c->dwarf.loc[EIP] = eip_loc;
c->dwarf.use_prev_instr = 1;
}
diff --git a/src/x86_64/Ginit.c b/src/x86_64/Ginit.c
index b7e8e462..64b800af 100644
--- a/src/x86_64/Ginit.c
+++ b/src/x86_64/Ginit.c
@@ -49,8 +49,6 @@ static struct unw_addr_space local_addr_space;

unw_addr_space_t unw_local_addr_space = &local_addr_space;

-HIDDEN unw_dyn_info_list_t _U_dyn_info_list;
-
/* XXX fix me: there is currently no way to locate the dyn-info list
by a remote unwinder. On ia64, this is done via a special
unwind-table entry. Perhaps something similar can be done with
@@ -66,7 +64,12 @@ static int
get_dyn_info_list_addr (unw_addr_space_t as, unw_word_t *dyn_info_list_addr,
void *arg)
{
- *dyn_info_list_addr = (unw_word_t) &_U_dyn_info_list;
+#ifndef UNW_LOCAL_ONLY
+# pragma weak _U_dyn_info_list_addr
+ if (!_U_dyn_info_list_addr)
+ return -UNW_ENOINFO;
+#endif
+ *dyn_info_list_addr = _U_dyn_info_list_addr ();
return 0;
}

diff --git a/src/x86_64/Gos-freebsd.c b/src/x86_64/Gos-freebsd.c
index 883025c8..8bb101ea 100644
index 8f28d1d8c..0c5a17940 100644
--- a/src/x86_64/Gos-freebsd.c
+++ b/src/x86_64/Gos-freebsd.c
@@ -133,6 +133,7 @@ x86_64_handle_signal_frame (unw_cursor_t *cursor)
Expand All @@ -359,7 +334,7 @@ index 883025c8..8bb101ea 100644
ret = dwarf_get (&c->dwarf, c->dwarf.loc[RIP], &c->dwarf.ip);
Debug (1, "Frame Chain [RIP=0x%Lx] = 0x%Lx\n",
diff --git a/src/x86_64/Gregs.c b/src/x86_64/Gregs.c
index baf8a24f..dff5bcbe 100644
index baf8a24f0..dff5bcbe7 100644
--- a/src/x86_64/Gregs.c
+++ b/src/x86_64/Gregs.c
@@ -79,7 +79,6 @@ tdep_access_reg (struct cursor *c, unw_regnum_t reg, unw_word_t *valp,
Expand All @@ -379,15 +354,15 @@ index baf8a24f..dff5bcbe 100644
case UNW_X86_64_RSI: loc = c->dwarf.loc[RSI]; break;
case UNW_X86_64_RDI: loc = c->dwarf.loc[RDI]; break;
diff --git a/src/x86_64/Gstep.c b/src/x86_64/Gstep.c
index 10498170..5425e3db 100644
index 3c5c3830f..fdad298c7 100644
--- a/src/x86_64/Gstep.c
+++ b/src/x86_64/Gstep.c
@@ -160,7 +160,7 @@ unw_step (unw_cursor_t *cursor)
{
unw_word_t rbp1 = 0;
rbp_loc = DWARF_LOC(rbp, 0);
- rsp_loc = DWARF_NULL_LOC;
+ rsp_loc = DWARF_VAL_LOC(c, rbp + 16);
rip_loc = DWARF_LOC (rbp + 8, 0);
ret = dwarf_get (&c->dwarf, rbp_loc, &rbp1);
Debug (1, "[RBP=0x%lx] = 0x%lx (cfa = 0x%lx) -> 0x%lx\n",
@@ -223,7 +223,7 @@ unw_step (unw_cursor_t *cursor)
Debug (2, "RIP fixup didn't work, falling back\n");
unw_word_t rbp1 = 0;
rbp_loc = DWARF_LOC(rbp, 0);
- rsp_loc = DWARF_NULL_LOC;
+ rsp_loc = DWARF_VAL_LOC(c, rbp + 16);
rip_loc = DWARF_LOC (rbp + 8, 0);
ret = dwarf_get (&c->dwarf, rbp_loc, &rbp1);
Debug (1, "[RBP=0x%lx] = 0x%lx (cfa = 0x%lx) -> 0x%lx\n",
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