Re: PING: PATCH: PR backtrace/14646: [x32] backtrace doesn't work

Mark Kettenis
2012-10-09T15:48:04Z

> Date: Tue, 9 Oct 2012 17:39:45 +0200 (CEST)
> From: Mark Kettenis <mark.kettenis@xs4all.nl>
>
> > Date: Tue, 9 Oct 2012 08:32:17 -0700
> > From: "H.J. Lu" <hjl.tools@gmail.com>
> >
> > On Mon, Oct 08, 2012 at 02:01:42PM -0700, H.J. Lu wrote:
> > > On Mon, Oct 08, 2012 at 10:47:26PM +0200, Mark Kettenis wrote:
> > > > > Date: Mon, 8 Oct 2012 13:38:21 -0700
> > > > > From: "H.J. Lu" <hjl.tools@gmail.com>
> > > > >
> > > > > On Mon, Oct 8, 2012 at 1:22 PM, Mark Kettenis <mark.kettenis@xs4all.nl> wrote:
> > > > > >> Date: Mon, 8 Oct 2012 13:04:03 -0700
> > > > > >> From: "H.J. Lu" <hjl.tools@gmail.com>
> > > > > >>
> > > > > >> On Mon, Oct 8, 2012 at 12:48 PM, Mark Kettenis <mark.kettenis@xs4all.nl> wrote:
> > > > > >> >> Date: Thu, 4 Oct 2012 06:57:22 -0700
> > > > > >> >> From: "H.J. Lu" <hjl.tools@gmail.com>
> > > > > >> >>
> > > > > >> >> On Wed, Oct 3, 2012 at 11:57 PM, Mark Kettenis <mark.kettenis@xs4all.nl> wrote:
> > > > > >> >> >
> > > > > >> >> > Perhaps the user-regs.c mechanism can be used to establish eip -> pc
> > > > > >> >> > and esp -> sp mappings?
> > > > > >> >>
> > > > > >> >> It doesn't help as long as gdbarch_pc_regnum/gdbarch_sp_regnum
> > > > > >> >> are used for both frame pc/sp value and unwind pc/sp value. For x32,
> > > > > >> >> we want eip/esp for frame pc/sp value and rip/rsp for unwind pc/sp
> > > > > >> >> value.
> > > > > >> >
> > > > > >> > That probably means we need to set gdbarch_pc_regnum (and
> > > > > >> > gdbarch_sp_regnum) to -1 for x32.
> > > > > >>
> > > > > >> We can't set gdbarch_pc_regnum/gdbarch_sp_regnum to -1:
> > > > > >>
> > > > > >>
> > > > > >> GNU gdb (GDB) 7.5.50.20121008-cvs
> > > > > >> Copyright (C) 2012 Free Software Foundation, Inc.
> > > > > >> License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
> > > > > >> This is free software: you are free to change and redistribute it.
> > > > > >> There is NO WARRANTY, to the extent permitted by law. Type "show copying"
> > > > > >> and "show warranty" for details.
> > > > > >> This GDB was configured as "x86_64-unknown-linux-gnu".
> > > > > >> For bug reporting instructions, please see:
> > > > > >> <http://www.gnu.org/software/gdb/bugs/>...
> > > > > >> Reading symbols from
> > > > > >> /export/build/gnu/glibc-x32/build-x86_64-linux/elf/sln...done.
> > > > > >> (gdb) b main
> > > > > >> Breakpoint 1 at 0x400c20: file sln.c, line 50.
> > > > > >> (gdb) r
> > > > > >> Starting program: /export/build/gnu/glibc-x32/build-x86_64-linux/elf/sln
> > > > > >> /export/gnu/import/git/gdb/gdb/regcache.c:1062: internal-error:
> > > > > >> regcache_read_pc: Unable to find PC
> > > > > >> A problem internal to GDB has been detected,
> > > > > >> further debugging may prove unreliable.
> > > > > >> Quit this debugging session? (y or n)
> > > > > >
> > > > > > Well, obviously you'll need to implement gdbarch_read_pc() for this to
> > > > > > work. And probably a few more gdbarch methods.
> > > > >
> > > > > What do we gain by setting gdbarch_pc_regnum/gdbarch_sp_regnum
> > > > > to -1? PC and SP are RIP and RSP for x32. We need them for
> > > > > stack unwind. The only unusual part is they are 64-bit although
> > > > > x32 is a 32-bit environment. How about this change?
> > > >
> > > > Did you even try that change?
> > > >
> > > > > diff --git a/gdb/features/i386/x32-core.xml b/gdb/features/i386/x32-core.xml
> > > > > index 1e41417..392ce24 100644
> > > > > --- a/gdb/features/i386/x32-core.xml
> > > > > +++ b/gdb/features/i386/x32-core.xml
> > > > > @@ -34,7 +34,7 @@
> > > > > <reg name="rsi" bitsize="64" type="int64"/>
> > > > > <reg name="rdi" bitsize="64" type="int64"/>
> > > > > <reg name="rbp" bitsize="64" type="int64"/>
> > > > > - <reg name="rsp" bitsize="64" type="int64"/>
> > > > > + <reg name="rsp" bitsize="64" type="data_ptr"/>
> > > > > <reg name="r8" bitsize="64" type="int64"/>
> > > > > <reg name="r9" bitsize="64" type="int64"/>
> > > > > <reg name="r10" bitsize="64" type="int64"/>
> > > > > @@ -44,7 +44,7 @@
> > > > > <reg name="r14" bitsize="64" type="int64"/>
> > > > > <reg name="r15" bitsize="64" type="int64"/>
> > > > >
> > > > > - <reg name="rip" bitsize="64" type="uint64"/>
> > > > > + <reg name="rip" bitsize="64" type="code_ptr"/>
> > > > > <reg name="eflags" bitsize="32" type="i386_eflags"/>
> > > > > <reg name="cs" bitsize="32" type="int32"/>
> > > > > <reg name="ss" bitsize="32" type="int32"/>
> > >
> > > Here is the patch I tried. It fixes PR backtrace/14646 and PR gdb/14647.
> > >
> > >
> > > H.J.
> > > ---
> > > 2012-10-08 H.J. Lu <hongjiu.lu@intel.com>
> > >
> > > PR backtrace/14646
> > > PR gdb/14647
> > > * amd64-tdep.c (amd64_x32_init_abi): Don't set sp_regnum_from_eax
> > > nor pc_regnum_from_eax.
> > > * i386-tdep.c (i386_gdbarch_init): Don't use sp_regnum_from_eax
> > > nor pc_regnum_from_eax.
> > > * i386-tdep.h (gdbarch_tdep): Remove sp_regnum_from_eax and
> > > pc_regnum_from_eax.
> > > * features/i386/x32-core.xml: Use data_ptr on rsp and use
> > > code_ptr on rip.
> > > * features/i386/x32-avx-linux.c: Regenerated.
> > > * features/i386/x32-avx.c: Likewise.
> > > * features/i386/x32-linux.c: Likewise.
> > > * features/i386/x32.c: Likewise.
> > >
> >
> > X32 needs to set RSP/RIP to 32-bit. Othewise, it won't work with gdbserver
> > since gdbserver will send 64-bit RSP/RIP while gdb sets size of RSP/RIP
> > to pointer size, which is 32-bit for x32. It works for x32 since the
> > upper 32bits of RSP/RIP are always zero for x32. OK for trunk and 7.5
> > branch.
>
> At least you figured out that your previous diff didn't work all by
> yourself. How about actually testing your diffs *before* you mail
> them out?

Oh, and even if this diff accidentally happens to work, it is a really
bad idea. You won't be able to diagnose problems caused by one of the
upper 32 bits getting set in %rsp or %rip.

> > 2012-10-08 H.J. Lu <hongjiu.lu@intel.com>
> >
> > PR backtrace/14646
> > PR gdb/14647
> > * amd64-tdep.c (amd64_x32_init_abi): Don't set sp_regnum_from_eax
> > nor pc_regnum_from_eax.
> > * i386-tdep.c (i386_gdbarch_init): Don't use sp_regnum_from_eax
> > nor pc_regnum_from_eax.
> > * i386-tdep.h (gdbarch_tdep): Remove sp_regnum_from_eax and
> > pc_regnum_from_eax.
> > * features/i386/x32-core.xml: Use data_ptr on rsp and use
> > code_ptr on rip.
> > * features/i386/x32-avx-linux.c: Regenerated.
> > * features/i386/x32-avx.c: Likewise.
> > * features/i386/x32-linux.c: Likewise.
> > * features/i386/x32.c: Likewise.
> > * regformats/i386/x32-avx-linux.dat: Likewise.
> > * regformats/i386/x32-avx.dat: Likewise.
> > * regformats/i386/x32-linux.dat: Likewise.
> > * regformats/i386/x32.dat: Likewise.
> >
> > diff --git a/gdb/amd64-tdep.c b/gdb/amd64-tdep.c
> > index 8c5b6cc..9cee464 100644
> > --- a/gdb/amd64-tdep.c
> > +++ b/gdb/amd64-tdep.c
> > @@ -2943,9 +2943,6 @@ amd64_x32_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
> > tdesc = tdesc_x32;
> > tdep->tdesc = tdesc;
> >
> > - tdep->sp_regnum_from_eax = AMD64_RSP_REGNUM;
> > - tdep->pc_regnum_from_eax = AMD64_RIP_REGNUM;
> > -
> > tdep->num_dword_regs = 17;
> > set_tdesc_pseudo_register_type (gdbarch, amd64_x32_pseudo_register_type);
> >
> > diff --git a/gdb/features/i386/x32-avx-linux.c b/gdb/features/i386/x32-avx-linux.c
> > index 1f39610..6efcffb 100644
> > --- a/gdb/features/i386/x32-avx-linux.c
> > +++ b/gdb/features/i386/x32-avx-linux.c
> > @@ -45,7 +45,7 @@ initialize_tdesc_x32_avx_linux (void)
> > tdesc_create_reg (feature, "rsi", 4, 1, NULL, 64, "int64");
> > tdesc_create_reg (feature, "rdi", 5, 1, NULL, 64, "int64");
> > tdesc_create_reg (feature, "rbp", 6, 1, NULL, 64, "int64");
> > - tdesc_create_reg (feature, "rsp", 7, 1, NULL, 64, "int64");
> > + tdesc_create_reg (feature, "rsp", 7, 1, NULL, 32, "data_ptr");
> > tdesc_create_reg (feature, "r8", 8, 1, NULL, 64, "int64");
> > tdesc_create_reg (feature, "r9", 9, 1, NULL, 64, "int64");
> > tdesc_create_reg (feature, "r10", 10, 1, NULL, 64, "int64");
> > @@ -54,7 +54,7 @@ initialize_tdesc_x32_avx_linux (void)
> > tdesc_create_reg (feature, "r13", 13, 1, NULL, 64, "int64");
> > tdesc_create_reg (feature, "r14", 14, 1, NULL, 64, "int64");
> > tdesc_create_reg (feature, "r15", 15, 1, NULL, 64, "int64");
> > - tdesc_create_reg (feature, "rip", 16, 1, NULL, 64, "uint64");
> > + tdesc_create_reg (feature, "rip", 16, 1, NULL, 32, "code_ptr");
> > tdesc_create_reg (feature, "eflags", 17, 1, NULL, 32, "i386_eflags");
> > tdesc_create_reg (feature, "cs", 18, 1, NULL, 32, "int32");
> > tdesc_create_reg (feature, "ss", 19, 1, NULL, 32, "int32");
> > diff --git a/gdb/features/i386/x32-avx.c b/gdb/features/i386/x32-avx.c
> > index fb7a12c..5b6d835 100644
> > --- a/gdb/features/i386/x32-avx.c
> > +++ b/gdb/features/i386/x32-avx.c
> > @@ -43,7 +43,7 @@ initialize_tdesc_x32_avx (void)
> > tdesc_create_reg (feature, "rsi", 4, 1, NULL, 64, "int64");
> > tdesc_create_reg (feature, "rdi", 5, 1, NULL, 64, "int64");
> > tdesc_create_reg (feature, "rbp", 6, 1, NULL, 64, "int64");
> > - tdesc_create_reg (feature, "rsp", 7, 1, NULL, 64, "int64");
> > + tdesc_create_reg (feature, "rsp", 7, 1, NULL, 32, "data_ptr");
> > tdesc_create_reg (feature, "r8", 8, 1, NULL, 64, "int64");
> > tdesc_create_reg (feature, "r9", 9, 1, NULL, 64, "int64");
> > tdesc_create_reg (feature, "r10", 10, 1, NULL, 64, "int64");
> > @@ -52,7 +52,7 @@ initialize_tdesc_x32_avx (void)
> > tdesc_create_reg (feature, "r13", 13, 1, NULL, 64, "int64");
> > tdesc_create_reg (feature, "r14", 14, 1, NULL, 64, "int64");
> > tdesc_create_reg (feature, "r15", 15, 1, NULL, 64, "int64");
> > - tdesc_create_reg (feature, "rip", 16, 1, NULL, 64, "uint64");
> > + tdesc_create_reg (feature, "rip", 16, 1, NULL, 32, "code_ptr");
> > tdesc_create_reg (feature, "eflags", 17, 1, NULL, 32, "i386_eflags");
> > tdesc_create_reg (feature, "cs", 18, 1, NULL, 32, "int32");
> > tdesc_create_reg (feature, "ss", 19, 1, NULL, 32, "int32");
> > diff --git a/gdb/features/i386/x32-core.xml b/gdb/features/i386/x32-core.xml
> > index 1e41417..28db826 100644
> > --- a/gdb/features/i386/x32-core.xml
> > +++ b/gdb/features/i386/x32-core.xml
> > @@ -34,7 +34,7 @@
> > <reg name="rsi" bitsize="64" type="int64"/>
> > <reg name="rdi" bitsize="64" type="int64"/>
> > <reg name="rbp" bitsize="64" type="int64"/>
> > - <reg name="rsp" bitsize="64" type="int64"/>
> > + <reg name="rsp" bitsize="32" type="data_ptr"/>
> > <reg name="r8" bitsize="64" type="int64"/>
> > <reg name="r9" bitsize="64" type="int64"/>
> > <reg name="r10" bitsize="64" type="int64"/>
> > @@ -44,7 +44,7 @@
> > <reg name="r14" bitsize="64" type="int64"/>
> > <reg name="r15" bitsize="64" type="int64"/>
> >
> > - <reg name="rip" bitsize="64" type="uint64"/>
> > + <reg name="rip" bitsize="32" type="code_ptr"/>
> > <reg name="eflags" bitsize="32" type="i386_eflags"/>
> > <reg name="cs" bitsize="32" type="int32"/>
> > <reg name="ss" bitsize="32" type="int32"/>
> > diff --git a/gdb/features/i386/x32-linux.c b/gdb/features/i386/x32-linux.c
> > index 387436f..d06fcbf 100644
> > --- a/gdb/features/i386/x32-linux.c
> > +++ b/gdb/features/i386/x32-linux.c
> > @@ -45,7 +45,7 @@ initialize_tdesc_x32_linux (void)
> > tdesc_create_reg (feature, "rsi", 4, 1, NULL, 64, "int64");
> > tdesc_create_reg (feature, "rdi", 5, 1, NULL, 64, "int64");
> > tdesc_create_reg (feature, "rbp", 6, 1, NULL, 64, "int64");
> > - tdesc_create_reg (feature, "rsp", 7, 1, NULL, 64, "int64");
> > + tdesc_create_reg (feature, "rsp", 7, 1, NULL, 32, "data_ptr");
> > tdesc_create_reg (feature, "r8", 8, 1, NULL, 64, "int64");
> > tdesc_create_reg (feature, "r9", 9, 1, NULL, 64, "int64");
> > tdesc_create_reg (feature, "r10", 10, 1, NULL, 64, "int64");
> > @@ -54,7 +54,7 @@ initialize_tdesc_x32_linux (void)
> > tdesc_create_reg (feature, "r13", 13, 1, NULL, 64, "int64");
> > tdesc_create_reg (feature, "r14", 14, 1, NULL, 64, "int64");
> > tdesc_create_reg (feature, "r15", 15, 1, NULL, 64, "int64");
> > - tdesc_create_reg (feature, "rip", 16, 1, NULL, 64, "uint64");
> > + tdesc_create_reg (feature, "rip", 16, 1, NULL, 32, "code_ptr");
> > tdesc_create_reg (feature, "eflags", 17, 1, NULL, 32, "i386_eflags");
> > tdesc_create_reg (feature, "cs", 18, 1, NULL, 32, "int32");
> > tdesc_create_reg (feature, "ss", 19, 1, NULL, 32, "int32");
> > diff --git a/gdb/features/i386/x32.c b/gdb/features/i386/x32.c
> > index 34e5087..679f767 100644
> > --- a/gdb/features/i386/x32.c
> > +++ b/gdb/features/i386/x32.c
> > @@ -43,7 +43,7 @@ initialize_tdesc_x32 (void)
> > tdesc_create_reg (feature, "rsi", 4, 1, NULL, 64, "int64");
> > tdesc_create_reg (feature, "rdi", 5, 1, NULL, 64, "int64");
> > tdesc_create_reg (feature, "rbp", 6, 1, NULL, 64, "int64");
> > - tdesc_create_reg (feature, "rsp", 7, 1, NULL, 64, "int64");
> > + tdesc_create_reg (feature, "rsp", 7, 1, NULL, 32, "data_ptr");
> > tdesc_create_reg (feature, "r8", 8, 1, NULL, 64, "int64");
> > tdesc_create_reg (feature, "r9", 9, 1, NULL, 64, "int64");
> > tdesc_create_reg (feature, "r10", 10, 1, NULL, 64, "int64");
> > @@ -52,7 +52,7 @@ initialize_tdesc_x32 (void)
> > tdesc_create_reg (feature, "r13", 13, 1, NULL, 64, "int64");
> > tdesc_create_reg (feature, "r14", 14, 1, NULL, 64, "int64");
> > tdesc_create_reg (feature, "r15", 15, 1, NULL, 64, "int64");
> > - tdesc_create_reg (feature, "rip", 16, 1, NULL, 64, "uint64");
> > + tdesc_create_reg (feature, "rip", 16, 1, NULL, 32, "code_ptr");
> > tdesc_create_reg (feature, "eflags", 17, 1, NULL, 32, "i386_eflags");
> > tdesc_create_reg (feature, "cs", 18, 1, NULL, 32, "int32");
> > tdesc_create_reg (feature, "ss", 19, 1, NULL, 32, "int32");
> > diff --git a/gdb/i386-tdep.c b/gdb/i386-tdep.c
> > index 84e9794..ddb20aa 100644
> > --- a/gdb/i386-tdep.c
> > +++ b/gdb/i386-tdep.c
> > @@ -7705,9 +7705,6 @@ i386_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
> > tdep->num_mmx_regs = 8;
> > tdep->num_ymm_regs = 0;
> >
> > - tdep->sp_regnum_from_eax = -1;
> > - tdep->pc_regnum_from_eax = -1;
> > -
> > tdesc_data = tdesc_data_alloc ();
> >
> > set_gdbarch_relocate_instruction (gdbarch, i386_relocate_instruction);
> > @@ -7752,14 +7749,6 @@ i386_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
> > /* Support dword pseudo-register if it hasn't been disabled. */
> > tdep->eax_regnum = ymm0_regnum;
> > ymm0_regnum += tdep->num_dword_regs;
> > - if (tdep->sp_regnum_from_eax != -1)
> > - set_gdbarch_sp_regnum (gdbarch,
> > - (tdep->eax_regnum
> > - + tdep->sp_regnum_from_eax));
> > - if (tdep->pc_regnum_from_eax != -1)
> > - set_gdbarch_pc_regnum (gdbarch,
> > - (tdep->eax_regnum
> > - + tdep->pc_regnum_from_eax));
> > }
> > else
> > tdep->eax_regnum = -1;
> > diff --git a/gdb/i386-tdep.h b/gdb/i386-tdep.h
> > index 76afdce..5f233f5 100644
> > --- a/gdb/i386-tdep.h
> > +++ b/gdb/i386-tdep.h
> > @@ -149,14 +149,6 @@ struct gdbarch_tdep
> > of pseudo dword register support. */
> > int eax_regnum;
> >
> > - /* Register number for SP, relative to %eax. Set this to -1 to
> > - indicate the absence of pseudo SP register support. */
> > - int sp_regnum_from_eax;
> > -
> > - /* Register number for PC, relative to %eax. Set this to -1 to
> > - indicate the absence of pseudo PC register support. */
> > - int pc_regnum_from_eax;
> > -
> > /* Number of core registers. */
> > int num_core_regs;
> >
> > diff --git a/gdb/regformats/i386/x32-avx-linux.dat b/gdb/regformats/i386/x32-avx-linux.dat
> > index 1203806..f142265 100644
> > --- a/gdb/regformats/i386/x32-avx-linux.dat
> > +++ b/gdb/regformats/i386/x32-avx-linux.dat
> > @@ -9,7 +9,7 @@ expedite:rbp,rsp,rip
> > 64:rsi
> > 64:rdi
> > 64:rbp
> > -64:rsp
> > +32:rsp
> > 64:r8
> > 64:r9
> > 64:r10
> > @@ -18,7 +18,7 @@ expedite:rbp,rsp,rip
> > 64:r13
> > 64:r14
> > 64:r15
> > -64:rip
> > +32:rip
> > 32:eflags
> > 32:cs
> > 32:ss
> > diff --git a/gdb/regformats/i386/x32-avx.dat b/gdb/regformats/i386/x32-avx.dat
> > index f13bf28..62e9d4a 100644
> > --- a/gdb/regformats/i386/x32-avx.dat
> > +++ b/gdb/regformats/i386/x32-avx.dat
> > @@ -9,7 +9,7 @@ expedite:rbp,rsp,rip
> > 64:rsi
> > 64:rdi
> > 64:rbp
> > -64:rsp
> > +32:rsp
> > 64:r8
> > 64:r9
> > 64:r10
> > @@ -18,7 +18,7 @@ expedite:rbp,rsp,rip
> > 64:r13
> > 64:r14
> > 64:r15
> > -64:rip
> > +32:rip
> > 32:eflags
> > 32:cs
> > 32:ss
> > diff --git a/gdb/regformats/i386/x32-linux.dat b/gdb/regformats/i386/x32-linux.dat
> > index 6eda64a..8cb27e1 100644
> > --- a/gdb/regformats/i386/x32-linux.dat
> > +++ b/gdb/regformats/i386/x32-linux.dat
> > @@ -9,7 +9,7 @@ expedite:rbp,rsp,rip
> > 64:rsi
> > 64:rdi
> > 64:rbp
> > -64:rsp
> > +32:rsp
> > 64:r8
> > 64:r9
> > 64:r10
> > @@ -18,7 +18,7 @@ expedite:rbp,rsp,rip
> > 64:r13
> > 64:r14
> > 64:r15
> > -64:rip
> > +32:rip
> > 32:eflags
> > 32:cs
> > 32:ss
> > diff --git a/gdb/regformats/i386/x32.dat b/gdb/regformats/i386/x32.dat
> > index 6c63a8a..4bee34e 100644
> > --- a/gdb/regformats/i386/x32.dat
> > +++ b/gdb/regformats/i386/x32.dat
> > @@ -9,7 +9,7 @@ expedite:rbp,rsp,rip
> > 64:rsi
> > 64:rdi
> > 64:rbp
> > -64:rsp
> > +32:rsp
> > 64:r8
> > 64:r9
> > 64:r10
> > @@ -18,7 +18,7 @@ expedite:rbp,rsp,rip
> > 64:r13
> > 64:r14
> > 64:r15
> > -64:rip
> > +32:rip
> > 32:eflags
> > 32:cs
> > 32:ss
> >
>