| Message ID | 20170203110607.97529-1-hekuang@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, Feb 03, 2017 at 11:06:05AM +0000, He Kuang wrote: > This patch changes the 'dwarfnum' to 'offset' in register table, so > the index of array becomes the dwarfnum (the index of each register > defined by DWARF) and the "offset" member means the byte-offset of the > register in (user_)pt_regs. This change makes the code consistent with > x86. > > Acked-by: Masami Hiramatsu <mhiramat@kernel.org> > Signed-off-by: He Kuang <hekuang@huawei.com> > --- > tools/perf/arch/arm64/util/dwarf-regs.c | 107 ++++++++++++++++---------------- > 1 file changed, 52 insertions(+), 55 deletions(-) Thanks for splitting this up. Comment below. > diff --git a/tools/perf/arch/arm64/util/dwarf-regs.c b/tools/perf/arch/arm64/util/dwarf-regs.c > index d49efeb..090f36b 100644 > --- a/tools/perf/arch/arm64/util/dwarf-regs.c > +++ b/tools/perf/arch/arm64/util/dwarf-regs.c > @@ -9,72 +9,69 @@ > */ > > #include <stddef.h> > +#include <linux/ptrace.h> /* for struct user_pt_regs */ > #include <dwarf-regs.h> > > -struct pt_regs_dwarfnum { > +struct pt_regs_offset { > const char *name; > - unsigned int dwarfnum; > + int offset; > }; > > -#define STR(s) #s > -#define REG_DWARFNUM_NAME(r, num) {.name = r, .dwarfnum = num} > -#define GPR_DWARFNUM_NAME(num) \ > - {.name = STR(%x##num), .dwarfnum = num} > -#define REG_DWARFNUM_END {.name = NULL, .dwarfnum = 0} > - > /* > * Reference: > * http://infocenter.arm.com/help/topic/com.arm.doc.ihi0057b/IHI0057B_aadwarf64.pdf > */ > -static const struct pt_regs_dwarfnum regdwarfnum_table[] = { > - GPR_DWARFNUM_NAME(0), > - GPR_DWARFNUM_NAME(1), > - GPR_DWARFNUM_NAME(2), > - GPR_DWARFNUM_NAME(3), > - GPR_DWARFNUM_NAME(4), > - GPR_DWARFNUM_NAME(5), > - GPR_DWARFNUM_NAME(6), > - GPR_DWARFNUM_NAME(7), > - GPR_DWARFNUM_NAME(8), > - GPR_DWARFNUM_NAME(9), > - GPR_DWARFNUM_NAME(10), > - GPR_DWARFNUM_NAME(11), > - GPR_DWARFNUM_NAME(12), > - GPR_DWARFNUM_NAME(13), > - GPR_DWARFNUM_NAME(14), > - GPR_DWARFNUM_NAME(15), > - GPR_DWARFNUM_NAME(16), > - GPR_DWARFNUM_NAME(17), > - GPR_DWARFNUM_NAME(18), > - GPR_DWARFNUM_NAME(19), > - GPR_DWARFNUM_NAME(20), > - GPR_DWARFNUM_NAME(21), > - GPR_DWARFNUM_NAME(22), > - GPR_DWARFNUM_NAME(23), > - GPR_DWARFNUM_NAME(24), > - GPR_DWARFNUM_NAME(25), > - GPR_DWARFNUM_NAME(26), > - GPR_DWARFNUM_NAME(27), > - GPR_DWARFNUM_NAME(28), > - GPR_DWARFNUM_NAME(29), > - REG_DWARFNUM_NAME("%lr", 30), > - REG_DWARFNUM_NAME("%sp", 31), > - REG_DWARFNUM_END, > -}; > +#define REG_OFFSET_NAME(r, num) {.name = "%" #r, \ > + .offset = offsetof(struct user_pt_regs, regs[num])} Whilst this works in practice, this is undefined behaviour for "sp", since you'll go off the end of the regs array. I still think you're better off sticking with the dwarfnum, then just having a dwarfnum2offset macro that multiplies by the size of a register. Will
hi 在 2017/2/3 21:00, Will Deacon 写道: > On Fri, Feb 03, 2017 at 11:06:05AM +0000, He Kuang wrote: >> This patch changes the 'dwarfnum' to 'offset' in register table, so >> the index of array becomes the dwarfnum (the index of each register >> defined by DWARF) and the "offset" member means the byte-offset of the >> register in (user_)pt_regs. This change makes the code consistent with >> x86. >> >> Acked-by: Masami Hiramatsu <mhiramat@kernel.org> >> Signed-off-by: He Kuang <hekuang@huawei.com> >> --- >> tools/perf/arch/arm64/util/dwarf-regs.c | 107 ++++++++++++++++---------------- >> 1 file changed, 52 insertions(+), 55 deletions(-) > Thanks for splitting this up. Comment below. > >> diff --git a/tools/perf/arch/arm64/util/dwarf-regs.c b/tools/perf/arch/arm64/util/dwarf-regs.c >> index d49efeb..090f36b 100644 >> --- a/tools/perf/arch/arm64/util/dwarf-regs.c >> +++ b/tools/perf/arch/arm64/util/dwarf-regs.c >> @@ -9,72 +9,69 @@ >> */ >> >> #include <stddef.h> >> +#include <linux/ptrace.h> /* for struct user_pt_regs */ >> #include <dwarf-regs.h> >> >> -struct pt_regs_dwarfnum { >> +struct pt_regs_offset { >> const char *name; >> - unsigned int dwarfnum; >> + int offset; >> }; >> >> -#define STR(s) #s >> -#define REG_DWARFNUM_NAME(r, num) {.name = r, .dwarfnum = num} >> -#define GPR_DWARFNUM_NAME(num) \ >> - {.name = STR(%x##num), .dwarfnum = num} >> -#define REG_DWARFNUM_END {.name = NULL, .dwarfnum = 0} >> - >> /* >> * Reference: >> * http://infocenter.arm.com/help/topic/com.arm.doc.ihi0057b/IHI0057B_aadwarf64.pdf >> */ >> -static const struct pt_regs_dwarfnum regdwarfnum_table[] = { >> - GPR_DWARFNUM_NAME(0), >> - GPR_DWARFNUM_NAME(1), >> - GPR_DWARFNUM_NAME(2), >> - GPR_DWARFNUM_NAME(3), >> - GPR_DWARFNUM_NAME(4), >> - GPR_DWARFNUM_NAME(5), >> - GPR_DWARFNUM_NAME(6), >> - GPR_DWARFNUM_NAME(7), >> - GPR_DWARFNUM_NAME(8), >> - GPR_DWARFNUM_NAME(9), >> - GPR_DWARFNUM_NAME(10), >> - GPR_DWARFNUM_NAME(11), >> - GPR_DWARFNUM_NAME(12), >> - GPR_DWARFNUM_NAME(13), >> - GPR_DWARFNUM_NAME(14), >> - GPR_DWARFNUM_NAME(15), >> - GPR_DWARFNUM_NAME(16), >> - GPR_DWARFNUM_NAME(17), >> - GPR_DWARFNUM_NAME(18), >> - GPR_DWARFNUM_NAME(19), >> - GPR_DWARFNUM_NAME(20), >> - GPR_DWARFNUM_NAME(21), >> - GPR_DWARFNUM_NAME(22), >> - GPR_DWARFNUM_NAME(23), >> - GPR_DWARFNUM_NAME(24), >> - GPR_DWARFNUM_NAME(25), >> - GPR_DWARFNUM_NAME(26), >> - GPR_DWARFNUM_NAME(27), >> - GPR_DWARFNUM_NAME(28), >> - GPR_DWARFNUM_NAME(29), >> - REG_DWARFNUM_NAME("%lr", 30), >> - REG_DWARFNUM_NAME("%sp", 31), >> - REG_DWARFNUM_END, >> -}; >> +#define REG_OFFSET_NAME(r, num) {.name = "%" #r, \ >> + .offset = offsetof(struct user_pt_regs, regs[num])} > Whilst this works in practice, this is undefined behaviour for "sp", since > you'll go off the end of the regs array. It's not undefined behaviour here, struct user_pt_regs { __u64 regs[31]; __u64 sp; __u64 pc; __u64 pstate; }; user_pt_regs->regs[31] is user_pt_regs->sp and the offset value is correct. > > I still think you're better off sticking with the dwarfnum, then just having > a dwarfnum2offset macro that multiplies by the size of a register. > > Will I think add a ptregs_offset field is more suitable and makes the code indepent to struct user_pt_regs layout, for example if the structure changed to this: struct user_pt_regs { __u64 sp; __u64 pc; __u64 pstate; __u64 regs[31]; }; The multiply result will be incorrect. Patch updated and the change is similar to commit "4679bccaa308" (perf tools powerpc: Add support for generating bpf prologue) Please review, thanks.
On Sat, Feb 04, 2017 at 05:03:20PM +0800, Hekuang wrote: > hi > > 在 2017/2/3 21:00, Will Deacon 写道: > >On Fri, Feb 03, 2017 at 11:06:05AM +0000, He Kuang wrote: > >>This patch changes the 'dwarfnum' to 'offset' in register table, so > >>the index of array becomes the dwarfnum (the index of each register > >>defined by DWARF) and the "offset" member means the byte-offset of the > >>register in (user_)pt_regs. This change makes the code consistent with > >>x86. > >> > >>Acked-by: Masami Hiramatsu <mhiramat@kernel.org> > >>Signed-off-by: He Kuang <hekuang@huawei.com> > >>--- > >> tools/perf/arch/arm64/util/dwarf-regs.c | 107 ++++++++++++++++---------------- > >> 1 file changed, 52 insertions(+), 55 deletions(-) > >Thanks for splitting this up. Comment below. > > > >>diff --git a/tools/perf/arch/arm64/util/dwarf-regs.c b/tools/perf/arch/arm64/util/dwarf-regs.c > >>index d49efeb..090f36b 100644 > >>--- a/tools/perf/arch/arm64/util/dwarf-regs.c > >>+++ b/tools/perf/arch/arm64/util/dwarf-regs.c > >>@@ -9,72 +9,69 @@ > >> */ > >> #include <stddef.h> > >>+#include <linux/ptrace.h> /* for struct user_pt_regs */ > >> #include <dwarf-regs.h> > >>-struct pt_regs_dwarfnum { > >>+struct pt_regs_offset { > >> const char *name; > >>- unsigned int dwarfnum; > >>+ int offset; > >> }; > >>-#define STR(s) #s > >>-#define REG_DWARFNUM_NAME(r, num) {.name = r, .dwarfnum = num} > >>-#define GPR_DWARFNUM_NAME(num) \ > >>- {.name = STR(%x##num), .dwarfnum = num} > >>-#define REG_DWARFNUM_END {.name = NULL, .dwarfnum = 0} > >>- > >> /* > >> * Reference: > >> * http://infocenter.arm.com/help/topic/com.arm.doc.ihi0057b/IHI0057B_aadwarf64.pdf > >> */ > >>-static const struct pt_regs_dwarfnum regdwarfnum_table[] = { > >>- GPR_DWARFNUM_NAME(0), > >>- GPR_DWARFNUM_NAME(1), > >>- GPR_DWARFNUM_NAME(2), > >>- GPR_DWARFNUM_NAME(3), > >>- GPR_DWARFNUM_NAME(4), > >>- GPR_DWARFNUM_NAME(5), > >>- GPR_DWARFNUM_NAME(6), > >>- GPR_DWARFNUM_NAME(7), > >>- GPR_DWARFNUM_NAME(8), > >>- GPR_DWARFNUM_NAME(9), > >>- GPR_DWARFNUM_NAME(10), > >>- GPR_DWARFNUM_NAME(11), > >>- GPR_DWARFNUM_NAME(12), > >>- GPR_DWARFNUM_NAME(13), > >>- GPR_DWARFNUM_NAME(14), > >>- GPR_DWARFNUM_NAME(15), > >>- GPR_DWARFNUM_NAME(16), > >>- GPR_DWARFNUM_NAME(17), > >>- GPR_DWARFNUM_NAME(18), > >>- GPR_DWARFNUM_NAME(19), > >>- GPR_DWARFNUM_NAME(20), > >>- GPR_DWARFNUM_NAME(21), > >>- GPR_DWARFNUM_NAME(22), > >>- GPR_DWARFNUM_NAME(23), > >>- GPR_DWARFNUM_NAME(24), > >>- GPR_DWARFNUM_NAME(25), > >>- GPR_DWARFNUM_NAME(26), > >>- GPR_DWARFNUM_NAME(27), > >>- GPR_DWARFNUM_NAME(28), > >>- GPR_DWARFNUM_NAME(29), > >>- REG_DWARFNUM_NAME("%lr", 30), > >>- REG_DWARFNUM_NAME("%sp", 31), > >>- REG_DWARFNUM_END, > >>-}; > >>+#define REG_OFFSET_NAME(r, num) {.name = "%" #r, \ > >>+ .offset = offsetof(struct user_pt_regs, regs[num])} > >Whilst this works in practice, this is undefined behaviour for "sp", since > >you'll go off the end of the regs array. > > It's not undefined behaviour here, > struct user_pt_regs { > __u64 regs[31]; > __u64 sp; > __u64 pc; > __u64 pstate; > }; > user_pt_regs->regs[31] is user_pt_regs->sp and the offset value is correct. I think it's undefined from the C standard perspective. > > > >I still think you're better off sticking with the dwarfnum, then just having > >a dwarfnum2offset macro that multiplies by the size of a register. > > > >Will > I think add a ptregs_offset field is more suitable and makes the code > indepent > to struct user_pt_regs layout, for example if the structure changed to this: > > struct user_pt_regs { > __u64 sp; > __u64 pc; > __u64 pstate; > __u64 regs[31]; > }; We won't reorder a uapi structure because that would binary compatibility. Just send a patch using the dwarfnum as the index for the offset calculation, like I've been saying since you posted the first version. Will
On Mon, 6 Feb 2017 13:02:29 +0000 Will Deacon <will.deacon@arm.com> wrote: > On Sat, Feb 04, 2017 at 05:03:20PM +0800, Hekuang wrote: > > hi > > > > 在 2017/2/3 21:00, Will Deacon 写道: > > >On Fri, Feb 03, 2017 at 11:06:05AM +0000, He Kuang wrote: > > >>This patch changes the 'dwarfnum' to 'offset' in register table, so > > >>the index of array becomes the dwarfnum (the index of each register > > >>defined by DWARF) and the "offset" member means the byte-offset of the > > >>register in (user_)pt_regs. This change makes the code consistent with > > >>x86. > > >> > > >>Acked-by: Masami Hiramatsu <mhiramat@kernel.org> > > >>Signed-off-by: He Kuang <hekuang@huawei.com> > > >>--- > > >> tools/perf/arch/arm64/util/dwarf-regs.c | 107 ++++++++++++++++---------------- > > >> 1 file changed, 52 insertions(+), 55 deletions(-) > > >Thanks for splitting this up. Comment below. > > > > > >>diff --git a/tools/perf/arch/arm64/util/dwarf-regs.c b/tools/perf/arch/arm64/util/dwarf-regs.c > > >>index d49efeb..090f36b 100644 > > >>--- a/tools/perf/arch/arm64/util/dwarf-regs.c > > >>+++ b/tools/perf/arch/arm64/util/dwarf-regs.c > > >>@@ -9,72 +9,69 @@ > > >> */ > > >> #include <stddef.h> > > >>+#include <linux/ptrace.h> /* for struct user_pt_regs */ > > >> #include <dwarf-regs.h> > > >>-struct pt_regs_dwarfnum { > > >>+struct pt_regs_offset { > > >> const char *name; > > >>- unsigned int dwarfnum; > > >>+ int offset; > > >> }; > > >>-#define STR(s) #s > > >>-#define REG_DWARFNUM_NAME(r, num) {.name = r, .dwarfnum = num} > > >>-#define GPR_DWARFNUM_NAME(num) \ > > >>- {.name = STR(%x##num), .dwarfnum = num} > > >>-#define REG_DWARFNUM_END {.name = NULL, .dwarfnum = 0} > > >>- > > >> /* > > >> * Reference: > > >> * http://infocenter.arm.com/help/topic/com.arm.doc.ihi0057b/IHI0057B_aadwarf64.pdf > > >> */ > > >>-static const struct pt_regs_dwarfnum regdwarfnum_table[] = { > > >>- GPR_DWARFNUM_NAME(0), > > >>- GPR_DWARFNUM_NAME(1), > > >>- GPR_DWARFNUM_NAME(2), > > >>- GPR_DWARFNUM_NAME(3), > > >>- GPR_DWARFNUM_NAME(4), > > >>- GPR_DWARFNUM_NAME(5), > > >>- GPR_DWARFNUM_NAME(6), > > >>- GPR_DWARFNUM_NAME(7), > > >>- GPR_DWARFNUM_NAME(8), > > >>- GPR_DWARFNUM_NAME(9), > > >>- GPR_DWARFNUM_NAME(10), > > >>- GPR_DWARFNUM_NAME(11), > > >>- GPR_DWARFNUM_NAME(12), > > >>- GPR_DWARFNUM_NAME(13), > > >>- GPR_DWARFNUM_NAME(14), > > >>- GPR_DWARFNUM_NAME(15), > > >>- GPR_DWARFNUM_NAME(16), > > >>- GPR_DWARFNUM_NAME(17), > > >>- GPR_DWARFNUM_NAME(18), > > >>- GPR_DWARFNUM_NAME(19), > > >>- GPR_DWARFNUM_NAME(20), > > >>- GPR_DWARFNUM_NAME(21), > > >>- GPR_DWARFNUM_NAME(22), > > >>- GPR_DWARFNUM_NAME(23), > > >>- GPR_DWARFNUM_NAME(24), > > >>- GPR_DWARFNUM_NAME(25), > > >>- GPR_DWARFNUM_NAME(26), > > >>- GPR_DWARFNUM_NAME(27), > > >>- GPR_DWARFNUM_NAME(28), > > >>- GPR_DWARFNUM_NAME(29), > > >>- REG_DWARFNUM_NAME("%lr", 30), > > >>- REG_DWARFNUM_NAME("%sp", 31), > > >>- REG_DWARFNUM_END, > > >>-}; > > >>+#define REG_OFFSET_NAME(r, num) {.name = "%" #r, \ > > >>+ .offset = offsetof(struct user_pt_regs, regs[num])} > > >Whilst this works in practice, this is undefined behaviour for "sp", since > > >you'll go off the end of the regs array. > > > > It's not undefined behaviour here, > > struct user_pt_regs { > > __u64 regs[31]; > > __u64 sp; > > __u64 pc; > > __u64 pstate; > > }; > > user_pt_regs->regs[31] is user_pt_regs->sp and the offset value is correct. > > I think it's undefined from the C standard perspective. Actually, this '%sp' is used for kprobes/uprobes dynamic events, which only depend on how regs_query_register_offset()@arch/arm64/kernel/ptrace.c is implemented. And also, since perf-probe uses debuginfo, it can find out the base register. So we don't need to care the C standard in this file :) Thank you,
On Tue, Feb 07, 2017 at 09:54:51AM +0900, Masami Hiramatsu wrote: > On Mon, 6 Feb 2017 13:02:29 +0000 > Will Deacon <will.deacon@arm.com> wrote: > > > On Sat, Feb 04, 2017 at 05:03:20PM +0800, Hekuang wrote: > > > hi > > > > > > 在 2017/2/3 21:00, Will Deacon 写道: > > > >On Fri, Feb 03, 2017 at 11:06:05AM +0000, He Kuang wrote: > > > >>This patch changes the 'dwarfnum' to 'offset' in register table, so > > > >>the index of array becomes the dwarfnum (the index of each register > > > >>defined by DWARF) and the "offset" member means the byte-offset of the > > > >>register in (user_)pt_regs. This change makes the code consistent with > > > >>x86. > > > >> > > > >>Acked-by: Masami Hiramatsu <mhiramat@kernel.org> > > > >>Signed-off-by: He Kuang <hekuang@huawei.com> > > > >>--- > > > >> tools/perf/arch/arm64/util/dwarf-regs.c | 107 ++++++++++++++++---------------- > > > >> 1 file changed, 52 insertions(+), 55 deletions(-) > > > >Thanks for splitting this up. Comment below. > > > > > > > >>diff --git a/tools/perf/arch/arm64/util/dwarf-regs.c b/tools/perf/arch/arm64/util/dwarf-regs.c > > > >>index d49efeb..090f36b 100644 > > > >>--- a/tools/perf/arch/arm64/util/dwarf-regs.c > > > >>+++ b/tools/perf/arch/arm64/util/dwarf-regs.c > > > >>@@ -9,72 +9,69 @@ > > > >> */ > > > >> #include <stddef.h> > > > >>+#include <linux/ptrace.h> /* for struct user_pt_regs */ > > > >> #include <dwarf-regs.h> > > > >>-struct pt_regs_dwarfnum { > > > >>+struct pt_regs_offset { > > > >> const char *name; > > > >>- unsigned int dwarfnum; > > > >>+ int offset; > > > >> }; > > > >>-#define STR(s) #s > > > >>-#define REG_DWARFNUM_NAME(r, num) {.name = r, .dwarfnum = num} > > > >>-#define GPR_DWARFNUM_NAME(num) \ > > > >>- {.name = STR(%x##num), .dwarfnum = num} > > > >>-#define REG_DWARFNUM_END {.name = NULL, .dwarfnum = 0} > > > >>- > > > >> /* > > > >> * Reference: > > > >> * http://infocenter.arm.com/help/topic/com.arm.doc.ihi0057b/IHI0057B_aadwarf64.pdf > > > >> */ > > > >>-static const struct pt_regs_dwarfnum regdwarfnum_table[] = { > > > >>- GPR_DWARFNUM_NAME(0), > > > >>- GPR_DWARFNUM_NAME(1), > > > >>- GPR_DWARFNUM_NAME(2), > > > >>- GPR_DWARFNUM_NAME(3), > > > >>- GPR_DWARFNUM_NAME(4), > > > >>- GPR_DWARFNUM_NAME(5), > > > >>- GPR_DWARFNUM_NAME(6), > > > >>- GPR_DWARFNUM_NAME(7), > > > >>- GPR_DWARFNUM_NAME(8), > > > >>- GPR_DWARFNUM_NAME(9), > > > >>- GPR_DWARFNUM_NAME(10), > > > >>- GPR_DWARFNUM_NAME(11), > > > >>- GPR_DWARFNUM_NAME(12), > > > >>- GPR_DWARFNUM_NAME(13), > > > >>- GPR_DWARFNUM_NAME(14), > > > >>- GPR_DWARFNUM_NAME(15), > > > >>- GPR_DWARFNUM_NAME(16), > > > >>- GPR_DWARFNUM_NAME(17), > > > >>- GPR_DWARFNUM_NAME(18), > > > >>- GPR_DWARFNUM_NAME(19), > > > >>- GPR_DWARFNUM_NAME(20), > > > >>- GPR_DWARFNUM_NAME(21), > > > >>- GPR_DWARFNUM_NAME(22), > > > >>- GPR_DWARFNUM_NAME(23), > > > >>- GPR_DWARFNUM_NAME(24), > > > >>- GPR_DWARFNUM_NAME(25), > > > >>- GPR_DWARFNUM_NAME(26), > > > >>- GPR_DWARFNUM_NAME(27), > > > >>- GPR_DWARFNUM_NAME(28), > > > >>- GPR_DWARFNUM_NAME(29), > > > >>- REG_DWARFNUM_NAME("%lr", 30), > > > >>- REG_DWARFNUM_NAME("%sp", 31), > > > >>- REG_DWARFNUM_END, > > > >>-}; > > > >>+#define REG_OFFSET_NAME(r, num) {.name = "%" #r, \ > > > >>+ .offset = offsetof(struct user_pt_regs, regs[num])} > > > >Whilst this works in practice, this is undefined behaviour for "sp", since > > > >you'll go off the end of the regs array. > > > > > > It's not undefined behaviour here, > > > struct user_pt_regs { > > > __u64 regs[31]; > > > __u64 sp; > > > __u64 pc; > > > __u64 pstate; > > > }; > > > user_pt_regs->regs[31] is user_pt_regs->sp and the offset value is correct. > > > > I think it's undefined from the C standard perspective. > > Actually, this '%sp' is used for kprobes/uprobes dynamic events, which only > depend on how regs_query_register_offset()@arch/arm64/kernel/ptrace.c is implemented. > And also, since perf-probe uses debuginfo, it can find out the base register. > > So we don't need to care the C standard in this file :) Up to the perf tool maintainers really, but I expect it will irritate anybody running UBSAN and it's really not difficult to fix. Will
On Tue, 7 Feb 2017 09:20:03 +0000 Will Deacon <will.deacon@arm.com> wrote: > On Tue, Feb 07, 2017 at 09:54:51AM +0900, Masami Hiramatsu wrote: > > On Mon, 6 Feb 2017 13:02:29 +0000 > > Will Deacon <will.deacon@arm.com> wrote: > > > > > On Sat, Feb 04, 2017 at 05:03:20PM +0800, Hekuang wrote: > > > > hi > > > > > > > > 在 2017/2/3 21:00, Will Deacon 写道: > > > > >On Fri, Feb 03, 2017 at 11:06:05AM +0000, He Kuang wrote: > > > > >>This patch changes the 'dwarfnum' to 'offset' in register table, so > > > > >>the index of array becomes the dwarfnum (the index of each register > > > > >>defined by DWARF) and the "offset" member means the byte-offset of the > > > > >>register in (user_)pt_regs. This change makes the code consistent with > > > > >>x86. > > > > >> > > > > >>Acked-by: Masami Hiramatsu <mhiramat@kernel.org> > > > > >>Signed-off-by: He Kuang <hekuang@huawei.com> > > > > >>--- > > > > >> tools/perf/arch/arm64/util/dwarf-regs.c | 107 ++++++++++++++++---------------- > > > > >> 1 file changed, 52 insertions(+), 55 deletions(-) > > > > >Thanks for splitting this up. Comment below. > > > > > > > > > >>diff --git a/tools/perf/arch/arm64/util/dwarf-regs.c b/tools/perf/arch/arm64/util/dwarf-regs.c > > > > >>index d49efeb..090f36b 100644 > > > > >>--- a/tools/perf/arch/arm64/util/dwarf-regs.c > > > > >>+++ b/tools/perf/arch/arm64/util/dwarf-regs.c > > > > >>@@ -9,72 +9,69 @@ > > > > >> */ > > > > >> #include <stddef.h> > > > > >>+#include <linux/ptrace.h> /* for struct user_pt_regs */ > > > > >> #include <dwarf-regs.h> > > > > >>-struct pt_regs_dwarfnum { > > > > >>+struct pt_regs_offset { > > > > >> const char *name; > > > > >>- unsigned int dwarfnum; > > > > >>+ int offset; > > > > >> }; > > > > >>-#define STR(s) #s > > > > >>-#define REG_DWARFNUM_NAME(r, num) {.name = r, .dwarfnum = num} > > > > >>-#define GPR_DWARFNUM_NAME(num) \ > > > > >>- {.name = STR(%x##num), .dwarfnum = num} > > > > >>-#define REG_DWARFNUM_END {.name = NULL, .dwarfnum = 0} > > > > >>- > > > > >> /* > > > > >> * Reference: > > > > >> * http://infocenter.arm.com/help/topic/com.arm.doc.ihi0057b/IHI0057B_aadwarf64.pdf > > > > >> */ > > > > >>-static const struct pt_regs_dwarfnum regdwarfnum_table[] = { > > > > >>- GPR_DWARFNUM_NAME(0), > > > > >>- GPR_DWARFNUM_NAME(1), > > > > >>- GPR_DWARFNUM_NAME(2), > > > > >>- GPR_DWARFNUM_NAME(3), > > > > >>- GPR_DWARFNUM_NAME(4), > > > > >>- GPR_DWARFNUM_NAME(5), > > > > >>- GPR_DWARFNUM_NAME(6), > > > > >>- GPR_DWARFNUM_NAME(7), > > > > >>- GPR_DWARFNUM_NAME(8), > > > > >>- GPR_DWARFNUM_NAME(9), > > > > >>- GPR_DWARFNUM_NAME(10), > > > > >>- GPR_DWARFNUM_NAME(11), > > > > >>- GPR_DWARFNUM_NAME(12), > > > > >>- GPR_DWARFNUM_NAME(13), > > > > >>- GPR_DWARFNUM_NAME(14), > > > > >>- GPR_DWARFNUM_NAME(15), > > > > >>- GPR_DWARFNUM_NAME(16), > > > > >>- GPR_DWARFNUM_NAME(17), > > > > >>- GPR_DWARFNUM_NAME(18), > > > > >>- GPR_DWARFNUM_NAME(19), > > > > >>- GPR_DWARFNUM_NAME(20), > > > > >>- GPR_DWARFNUM_NAME(21), > > > > >>- GPR_DWARFNUM_NAME(22), > > > > >>- GPR_DWARFNUM_NAME(23), > > > > >>- GPR_DWARFNUM_NAME(24), > > > > >>- GPR_DWARFNUM_NAME(25), > > > > >>- GPR_DWARFNUM_NAME(26), > > > > >>- GPR_DWARFNUM_NAME(27), > > > > >>- GPR_DWARFNUM_NAME(28), > > > > >>- GPR_DWARFNUM_NAME(29), > > > > >>- REG_DWARFNUM_NAME("%lr", 30), > > > > >>- REG_DWARFNUM_NAME("%sp", 31), > > > > >>- REG_DWARFNUM_END, > > > > >>-}; > > > > >>+#define REG_OFFSET_NAME(r, num) {.name = "%" #r, \ > > > > >>+ .offset = offsetof(struct user_pt_regs, regs[num])} > > > > >Whilst this works in practice, this is undefined behaviour for "sp", since > > > > >you'll go off the end of the regs array. > > > > > > > > It's not undefined behaviour here, > > > > struct user_pt_regs { > > > > __u64 regs[31]; > > > > __u64 sp; > > > > __u64 pc; > > > > __u64 pstate; > > > > }; > > > > user_pt_regs->regs[31] is user_pt_regs->sp and the offset value is correct. > > > > > > I think it's undefined from the C standard perspective. > > > > Actually, this '%sp' is used for kprobes/uprobes dynamic events, which only > > depend on how regs_query_register_offset()@arch/arm64/kernel/ptrace.c is implemented. > > And also, since perf-probe uses debuginfo, it can find out the base register. > > > > So we don't need to care the C standard in this file :) > > Up to the perf tool maintainers really, but I expect it will irritate > anybody running UBSAN and it's really not difficult to fix. Hmm, sorry, I'm not sure, what the point UBSAN user be irriteted? And what is that related to this story? Thank you,
diff --git a/tools/perf/arch/arm64/util/dwarf-regs.c b/tools/perf/arch/arm64/util/dwarf-regs.c index d49efeb..090f36b 100644 --- a/tools/perf/arch/arm64/util/dwarf-regs.c +++ b/tools/perf/arch/arm64/util/dwarf-regs.c @@ -9,72 +9,69 @@ */ #include <stddef.h> +#include <linux/ptrace.h> /* for struct user_pt_regs */ #include <dwarf-regs.h> -struct pt_regs_dwarfnum { +struct pt_regs_offset { const char *name; - unsigned int dwarfnum; + int offset; }; -#define STR(s) #s -#define REG_DWARFNUM_NAME(r, num) {.name = r, .dwarfnum = num} -#define GPR_DWARFNUM_NAME(num) \ - {.name = STR(%x##num), .dwarfnum = num} -#define REG_DWARFNUM_END {.name = NULL, .dwarfnum = 0} - /* * Reference: * http://infocenter.arm.com/help/topic/com.arm.doc.ihi0057b/IHI0057B_aadwarf64.pdf */ -static const struct pt_regs_dwarfnum regdwarfnum_table[] = { - GPR_DWARFNUM_NAME(0), - GPR_DWARFNUM_NAME(1), - GPR_DWARFNUM_NAME(2), - GPR_DWARFNUM_NAME(3), - GPR_DWARFNUM_NAME(4), - GPR_DWARFNUM_NAME(5), - GPR_DWARFNUM_NAME(6), - GPR_DWARFNUM_NAME(7), - GPR_DWARFNUM_NAME(8), - GPR_DWARFNUM_NAME(9), - GPR_DWARFNUM_NAME(10), - GPR_DWARFNUM_NAME(11), - GPR_DWARFNUM_NAME(12), - GPR_DWARFNUM_NAME(13), - GPR_DWARFNUM_NAME(14), - GPR_DWARFNUM_NAME(15), - GPR_DWARFNUM_NAME(16), - GPR_DWARFNUM_NAME(17), - GPR_DWARFNUM_NAME(18), - GPR_DWARFNUM_NAME(19), - GPR_DWARFNUM_NAME(20), - GPR_DWARFNUM_NAME(21), - GPR_DWARFNUM_NAME(22), - GPR_DWARFNUM_NAME(23), - GPR_DWARFNUM_NAME(24), - GPR_DWARFNUM_NAME(25), - GPR_DWARFNUM_NAME(26), - GPR_DWARFNUM_NAME(27), - GPR_DWARFNUM_NAME(28), - GPR_DWARFNUM_NAME(29), - REG_DWARFNUM_NAME("%lr", 30), - REG_DWARFNUM_NAME("%sp", 31), - REG_DWARFNUM_END, -}; +#define REG_OFFSET_NAME(r, num) {.name = "%" #r, \ + .offset = offsetof(struct user_pt_regs, regs[num])} +#define REG_OFFSET_END {.name = NULL, .offset = 0} +#define GPR_OFFSET_NAME(r) \ + {.name = "%x" #r, .offset = offsetof(struct user_pt_regs, regs[r])} -/** - * get_arch_regstr() - lookup register name from it's DWARF register number - * @n: the DWARF register number - * - * get_arch_regstr() returns the name of the register in struct - * regdwarfnum_table from it's DWARF register number. If the register is not - * found in the table, this returns NULL; +/* This table is for reverse searching for the offset or register + * names in aarch64_regstr_tbl[]. */ +static const struct pt_regs_offset regoffset_table[] = { + GPR_OFFSET_NAME(0), + GPR_OFFSET_NAME(1), + GPR_OFFSET_NAME(2), + GPR_OFFSET_NAME(3), + GPR_OFFSET_NAME(4), + GPR_OFFSET_NAME(5), + GPR_OFFSET_NAME(6), + GPR_OFFSET_NAME(7), + GPR_OFFSET_NAME(8), + GPR_OFFSET_NAME(9), + GPR_OFFSET_NAME(10), + GPR_OFFSET_NAME(11), + GPR_OFFSET_NAME(12), + GPR_OFFSET_NAME(13), + GPR_OFFSET_NAME(14), + GPR_OFFSET_NAME(15), + GPR_OFFSET_NAME(16), + GPR_OFFSET_NAME(17), + GPR_OFFSET_NAME(18), + GPR_OFFSET_NAME(19), + GPR_OFFSET_NAME(20), + GPR_OFFSET_NAME(21), + GPR_OFFSET_NAME(22), + GPR_OFFSET_NAME(23), + GPR_OFFSET_NAME(24), + GPR_OFFSET_NAME(25), + GPR_OFFSET_NAME(26), + GPR_OFFSET_NAME(27), + GPR_OFFSET_NAME(28), + GPR_OFFSET_NAME(29), + REG_OFFSET_NAME(lr, 30), + REG_OFFSET_NAME(sp, 31), + REG_OFFSET_END, +}; + +/* Minus 1 for the ending REG_OFFSET_END */ +#define ARCH_MAX_REGS ((sizeof(regoffset_table) / \ + sizeof(regoffset_table[0])) - 1) + +/* Return architecture dependent register string (for kprobe-tracer) */ const char *get_arch_regstr(unsigned int n) { - const struct pt_regs_dwarfnum *roff; - for (roff = regdwarfnum_table; roff->name != NULL; roff++) - if (roff->dwarfnum == n) - return roff->name; - return NULL; + return (n < ARCH_MAX_REGS) ? regoffset_table[n].name : NULL; }