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From: <sv...@va...> - 2015-06-04 19:44:56
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Author: philippe
Date: Thu Jun 4 20:44:47 2015
New Revision: 15309
Log:
On platforms that have an accessible redzone below the SP, the unwind logic
should be able to access the redzone.
So, when computing fp_min, substract the redzone.
Currently, only amd64 and ppc64 have a non 0 redzone.
Regtested on amd64 and ppc64le, no regression.
Modified:
trunk/coregrind/m_stacktrace.c
Modified: trunk/coregrind/m_stacktrace.c
==============================================================================
--- trunk/coregrind/m_stacktrace.c (original)
+++ trunk/coregrind/m_stacktrace.c Thu Jun 4 20:44:47 2015
@@ -75,7 +75,20 @@
} \
}
-
+/* Note about calculation of fp_min : fp_min is the lowest address
+ which can be accessed during unwinding. This is SP - VG_STACK_REDZONE_SZB.
+ On most platforms, this will be equal to SP (as VG_STACK_REDZONE_SZB
+ is 0). However, on some platforms (e.g. amd64), there is an accessible
+ redzone below the SP. Some CFI unwind info are generated, taking this
+ into account. As an example, the following is a CFI unwind info on
+ amd64 found for a 'retq' instruction:
+[0x400f7e .. 0x400f7e]: let cfa=oldSP+8 in RA=*(cfa+-8) SP=cfa+0 BP=*(cfa+-16)
+ 0x400f7e: retq
+ As you can see, the previous BP is found 16 bytes below the cfa, which
+ is the oldSP+8. So, effectively, the BP is found 8 bytes below the SP.
+ The fp_min must take this into account, otherwise, VG_(use_CF_info) will
+ not unwind the BP. */
+
/* ------------------------ x86 ------------------------- */
#if defined(VGP_x86_linux) || defined(VGP_x86_darwin)
@@ -196,7 +209,7 @@
uregs.xip = (Addr)startRegs->r_pc;
uregs.xsp = (Addr)startRegs->r_sp;
uregs.xbp = startRegs->misc.X86.r_ebp;
- Addr fp_min = uregs.xsp;
+ Addr fp_min = uregs.xsp - VG_STACK_REDZONE_SZB;
/* Snaffle IPs from the client's stack into ips[0 .. max_n_ips-1],
stopping when the trail goes cold, which we guess to be
@@ -479,7 +492,7 @@
uregs.xip = startRegs->r_pc;
uregs.xsp = startRegs->r_sp;
uregs.xbp = startRegs->misc.AMD64.r_rbp;
- Addr fp_min = uregs.xsp;
+ Addr fp_min = uregs.xsp - VG_STACK_REDZONE_SZB;
/* Snaffle IPs from the client's stack into ips[0 .. max_n_ips-1],
stopping when the trail goes cold, which we guess to be
@@ -682,7 +695,7 @@
# elif defined(VGP_ppc64be_linux) || defined(VGP_ppc64le_linux)
Addr lr = startRegs->misc.PPC64.r_lr;
# endif
- Addr fp_min = sp;
+ Addr fp_min = sp - VG_STACK_REDZONE_SZB;
/* Snaffle IPs from the client's stack into ips[0 .. max_n_ips-1],
stopping when the trail goes cold, which we guess to be
@@ -947,7 +960,7 @@
uregs.r12 = startRegs->misc.ARM.r12;
uregs.r11 = startRegs->misc.ARM.r11;
uregs.r7 = startRegs->misc.ARM.r7;
- Addr fp_min = uregs.r13;
+ Addr fp_min = uregs.r13 - VG_STACK_REDZONE_SZB;
/* Snaffle IPs from the client's stack into ips[0 .. max_n_ips-1],
stopping when the trail goes cold, which we guess to be
@@ -1091,7 +1104,7 @@
uregs.sp = startRegs->r_sp;
uregs.x30 = startRegs->misc.ARM64.x30;
uregs.x29 = startRegs->misc.ARM64.x29;
- Addr fp_min = uregs.sp;
+ Addr fp_min = uregs.sp - VG_STACK_REDZONE_SZB;
/* Snaffle IPs from the client's stack into ips[0 .. max_n_ips-1],
stopping when the trail goes cold, which we guess to be
@@ -1185,7 +1198,7 @@
D3UnwindRegs uregs;
uregs.ia = startRegs->r_pc;
uregs.sp = startRegs->r_sp;
- Addr fp_min = uregs.sp;
+ Addr fp_min = uregs.sp - VG_STACK_REDZONE_SZB;
uregs.fp = startRegs->misc.S390X.r_fp;
uregs.lr = startRegs->misc.S390X.r_lr;
@@ -1268,7 +1281,7 @@
D3UnwindRegs uregs;
uregs.pc = startRegs->r_pc;
uregs.sp = startRegs->r_sp;
- Addr fp_min = uregs.sp;
+ Addr fp_min = uregs.sp - VG_STACK_REDZONE_SZB;
#if defined(VGP_mips32_linux)
uregs.fp = startRegs->misc.MIPS32.r30;
@@ -1423,7 +1436,7 @@
D3UnwindRegs uregs;
uregs.pc = startRegs->r_pc;
uregs.sp = startRegs->r_sp;
- Addr fp_min = uregs.sp;
+ Addr fp_min = uregs.sp - VG_STACK_REDZONE_SZB;
uregs.fp = startRegs->misc.TILEGX.r52;
uregs.lr = startRegs->misc.TILEGX.r55;
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