[PATCH 1/4] perf tools: unwind: ensure unwind hooks return negative errorno.

Wang Nan
2015-04-01T10:33:36Z

According to man pages of libunwind, unwind hooks should return
'negative value of one of the unw_error_t error-codes', they are
different from generic error code. In addition, access_dso_mem()
returns '!(size == sizeof(*data))', compiler never ensure it is
negative when failure, which causes libunwind get undesire value
when accessing //anon memory.

This patch fixes this problem by force returning negative value when
error, instead of returning 'ret' itself when it is non-zero.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
---
tools/perf/util/unwind-libunwind.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/tools/perf/util/unwind-libunwind.c b/tools/perf/util/unwind-libunwind.c
index 7b09a44..78a32c7 100644
--- a/tools/perf/util/unwind-libunwind.c
+++ b/tools/perf/util/unwind-libunwind.c
@@ -422,7 +422,7 @@ static int access_dso_mem(struct unwind_info *ui, unw_word_t addr,
size = dso__data_read_addr(al.map->dso, al.map, ui->machine,
addr, (u8 *) data, sizeof(*data));

- return !(size == sizeof(*data));
+ return (size == sizeof(*data)) ? 0 : -UNW_EINVAL;
}

static int access_mem(unw_addr_space_t __maybe_unused as,
@@ -443,13 +443,13 @@ static int access_mem(unw_addr_space_t __maybe_unused as,

ret = perf_reg_value(&start, &ui->sample->user_regs, PERF_REG_SP);
if (ret)
- return ret;
+ return -UNW_EBADREG;

end = start + stack->size;

/* Check overflow. */
if (addr + sizeof(unw_word_t) < addr)
- return -EINVAL;
+ return -UNW_EINVAL;

if (addr < start || addr + sizeof(unw_word_t) >= end) {
ret = access_dso_mem(ui, addr, valp);
@@ -491,12 +491,12 @@ static int access_reg(unw_addr_space_t __maybe_unused as,

id = libunwind__arch_reg_id(regnum);
if (id < 0)
- return -EINVAL;
+ return -UNW_EBADREG;

ret = perf_reg_value(&val, &ui->sample->user_regs, id);
if (ret) {
pr_err("unwind: can't read reg %d\n", regnum);
- return ret;
+ return -UNW_EBADREG;
}

*valp = (unw_word_t) val;
--
1.8.3.4