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Message-ID: <4FBB0771.1010009@gmail.com>
Date: Mon, 21 May 2012 21:26:41 -0600
From: David Ahern <dsahern@...il.com>
To: Jiri Olsa <jolsa@...hat.com>
CC: acme@...hat.com, a.p.zijlstra@...llo.nl, mingo@...e.hu,
paulus@...ba.org, cjashfor@...ux.vnet.ibm.com, fweisbec@...il.com,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/7] perf, tool: Handle different endians properly during
symbol load
On 5/16/12 12:59 AM, Jiri Olsa wrote:
> Currently we dont care about the file object's endianness. It's possible
> we read buildid file object from different architecture than we are
> currentlly running on. So we need to care about properly reading such
> object's data - handle different endianness properly.
>
> Adding:
> needs_swap DSO field
> dso__swap_init function to initialize DSO's needs_swap
> DSO__READ to read the data with proper swaps
>
> Note, running following to test perf endianity handling:
> test 1)
> - origin system:
> # perf record -a -- sleep 10 (any perf record will do)
> # perf report> report.origin
> # perf archive perf.data
>
> - copy the perf.data, report.origin and perf.data.tar.bz2
> to a target system and run:
> # tar xjvf perf.data.tar.bz2 -C ~/.debug
> # perf report> report.target
> # diff -u report.origin report.target
>
> - the diff should produce no output
> (besides some white space stuff and possibly different
> date/TZ output)
>
> test 1)
> - origin system:
> # perf record -ag -fo /tmp/perf.data -- sleep 1
> - mount origin system root to the target system on /mnt/origin
> - target system:
> # perf script --symfs /mnt/origin -I -i /mnt/origin/tmp/perf.data \
> --kallsyms /mnt/origin/proc/kallsyms
> - complete perf.data header is displayed
>
> Signed-off-by: Jiri Olsa<jolsa@...hat.com>
> ---
> tools/perf/util/symbol.c | 33 ++++++++++++++++++++++++++++++++-
> tools/perf/util/symbol.h | 30 ++++++++++++++++++++++++++++++
> 2 files changed, 62 insertions(+), 1 deletions(-)
>
> diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
> index e2ba885..04a83c5 100644
> --- a/tools/perf/util/symbol.c
> +++ b/tools/perf/util/symbol.c
> @@ -323,6 +323,7 @@ struct dso *dso__new(const char *name)
> dso->sorted_by_name = 0;
> dso->has_build_id = 0;
> dso->kernel = DSO_TYPE_USER;
> + dso->needs_swap = DSO_SWAP__UNSET;
> INIT_LIST_HEAD(&dso->node);
> }
>
> @@ -1156,6 +1157,33 @@ static size_t elf_addr_to_index(Elf *elf, GElf_Addr addr)
> return -1;
> }
>
> +static int dso__swap_init(struct dso *dso, unsigned char eidata)
> +{
> + static unsigned int const endian = 1;
> +
> + dso->needs_swap = DSO_SWAP__NO;
> +
> + switch (eidata) {
> + case ELFDATA2LSB:
> + /* We are big endian, DSO is little endian. */
> + if (*(unsigned char const *)&endian != 1)
> + dso->needs_swap = DSO_SWAP__YES;
> + break;
> +
> + case ELFDATA2MSB:
> + /* We are little endian, DSO is big endian. */
> + if (*(unsigned char const *)&endian != 0)
> + dso->needs_swap = DSO_SWAP__YES;
> + break;
> +
> + default:
> + pr_err("unrecognized DSO data encoding %d\n", eidata);
> + return -EINVAL;
> + }
> +
> + return 0;
> +}
> +
> static int dso__load_sym(struct dso *dso, struct map *map, const char *name,
> int fd, symbol_filter_t filter, int kmodule,
> int want_symtab)
> @@ -1187,6 +1215,9 @@ static int dso__load_sym(struct dso *dso, struct map *map, const char *name,
> goto out_elf_end;
> }
>
> + if (dso__swap_init(dso, ehdr.e_ident[EI_DATA]))
> + goto out_elf_end;
> +
> /* Always reject images with a mismatched build-id: */
> if (dso->has_build_id) {
> u8 build_id[BUILD_ID_SIZE];
> @@ -1272,7 +1303,7 @@ static int dso__load_sym(struct dso *dso, struct map *map, const char *name,
> if (opdsec&& sym.st_shndx == opdidx) {
> u32 offset = sym.st_value - opdshdr.sh_addr;
> u64 *opd = opddata->d_buf + offset;
> - sym.st_value = *opd;
> + sym.st_value = DSO__READ(dso, u64, *opd);
> sym.st_shndx = elf_addr_to_index(elf, sym.st_value);
> }
>
> diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h
> index 5649d63..be14744 100644
> --- a/tools/perf/util/symbol.h
> +++ b/tools/perf/util/symbol.h
> @@ -9,6 +9,7 @@
> #include<linux/list.h>
> #include<linux/rbtree.h>
> #include<stdio.h>
> +#include<byteswap.h>
>
> #ifdef HAVE_CPLUS_DEMANGLE
> extern char *cplus_demangle(const char *, int);
> @@ -160,11 +161,18 @@ enum dso_kernel_type {
> DSO_TYPE_GUEST_KERNEL
> };
>
> +enum dso_swap_type {
> + DSO_SWAP__UNSET,
> + DSO_SWAP__NO,
> + DSO_SWAP__YES,
> +};
> +
> struct dso {
> struct list_head node;
> struct rb_root symbols[MAP__NR_TYPES];
> struct rb_root symbol_names[MAP__NR_TYPES];
> enum dso_kernel_type kernel;
> + enum dso_swap_type needs_swap;
> u8 adjust_symbols:1;
> u8 has_build_id:1;
> u8 hit:1;
> @@ -182,6 +190,28 @@ struct dso {
> char name[0];
> };
>
> +#define DSO__READ(dso, type, val) \
s/DSO__READ/DSO__SWAP/? it's swapping byes, not reading.
David
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