* [PATCH v2 0/2] perf: Fix bpf prologue generation, uaccess
@ 2020-06-09 8:10 Sumanth Korikkar
2020-06-09 8:10 ` [PATCH v2 1/2] perf: Fix user attribute access in kprobes Sumanth Korikkar
2020-06-09 8:10 ` [PATCH v2 2/2] perf: Fix bpf prologue generation Sumanth Korikkar
0 siblings, 2 replies; 6+ messages in thread
From: Sumanth Korikkar @ 2020-06-09 8:10 UTC (permalink / raw
To: linux-perf-users, acme
Cc: bpf, jolsa, tmricht, heiko.carstens, mhiramat, iii,
Sumanth Korikkar
Patches:
1. Fix bpf prologue generation. bpf_probe_read is unavailable for arch
with overlapping address space. If uaccess, use bpf_probe_read_user.
Otherwise, use bpf_probe_read_kernel.
2. Fix uaccess in kprobes. Now perf probe add with @user attribute works
v1->v2:
- Split the patches and add Acked-By
Thank you.
Sumanth Korikkar (2):
perf: Fix user attribute access in kprobes
perf: Fix bpf prologue generation
tools/perf/util/bpf-prologue.c | 14 ++++++++++----
tools/perf/util/probe-event.c | 7 +++++--
tools/perf/util/probe-file.c | 2 +-
3 files changed, 16 insertions(+), 7 deletions(-)
--
2.17.1
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH v2 1/2] perf: Fix user attribute access in kprobes
2020-06-09 8:10 [PATCH v2 0/2] perf: Fix bpf prologue generation, uaccess Sumanth Korikkar
@ 2020-06-09 8:10 ` Sumanth Korikkar
2020-06-09 15:09 ` Arnaldo Carvalho de Melo
2020-06-09 8:10 ` [PATCH v2 2/2] perf: Fix bpf prologue generation Sumanth Korikkar
1 sibling, 1 reply; 6+ messages in thread
From: Sumanth Korikkar @ 2020-06-09 8:10 UTC (permalink / raw
To: linux-perf-users, acme
Cc: bpf, jolsa, tmricht, heiko.carstens, mhiramat, iii,
Sumanth Korikkar
Issue:
perf probe -a 'do_sched_setscheduler pid policy
param->sched_priority@user' did not work before.
Fix:
Make (perf probe -a 'do_sched_setscheduler pid policy
param->sched_priority@user') output equivalent to ftrace
('p:probe/do_sched_setscheduler _text+517384 pid=%r2:s32 policy=%r3:s32
sched_priority=+u0(%r4):s32' > kprobe_events)
Other:
1. Right now, __match_glob() does not handle [u]<offset>. For now, use
*u]<offset>.
2. @user attribute was introduced in commit 1e032f7cfa14 ("perf-probe:
Add user memory access attribute support")
Test:
1. perf probe -a 'do_sched_setscheduler pid policy
param->sched_priority@user'
2 ./perf script
sched 305669 [000] 1614458.838675: perf_bpf_probe:func: (2904e508)
pid=261614 policy=2 sched_priority=1
3. cat /sys/kernel/debug/tracing/trace
<...>-309956 [006] .... 1616098.093957: 0: prio: 1
Signed-off-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Reviewed-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
---
tools/perf/util/probe-event.c | 7 +++++--
tools/perf/util/probe-file.c | 2 +-
2 files changed, 6 insertions(+), 3 deletions(-)
diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index a08f373d3305..df713a5d1e26 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -1575,7 +1575,7 @@ static int parse_perf_probe_arg(char *str, struct perf_probe_arg *arg)
}
tmp = strchr(str, '@');
- if (tmp && tmp != str && strcmp(tmp + 1, "user")) { /* user attr */
+ if (tmp && tmp != str && !strcmp(tmp + 1, "user")) { /* user attr */
if (!user_access_is_supported()) {
semantic_error("ftrace does not support user access\n");
return -EINVAL;
@@ -1995,7 +1995,10 @@ static int __synthesize_probe_trace_arg_ref(struct probe_trace_arg_ref *ref,
if (depth < 0)
return depth;
}
- err = strbuf_addf(buf, "%+ld(", ref->offset);
+ if (ref->user_access)
+ err = strbuf_addf(buf, "%s%ld(", "+u", ref->offset);
+ else
+ err = strbuf_addf(buf, "%+ld(", ref->offset);
return (err < 0) ? err : depth;
}
diff --git a/tools/perf/util/probe-file.c b/tools/perf/util/probe-file.c
index 8c852948513e..064b63a6a3f3 100644
--- a/tools/perf/util/probe-file.c
+++ b/tools/perf/util/probe-file.c
@@ -1044,7 +1044,7 @@ static struct {
DEFINE_TYPE(FTRACE_README_PROBE_TYPE_X, "*type: * x8/16/32/64,*"),
DEFINE_TYPE(FTRACE_README_KRETPROBE_OFFSET, "*place (kretprobe): *"),
DEFINE_TYPE(FTRACE_README_UPROBE_REF_CTR, "*ref_ctr_offset*"),
- DEFINE_TYPE(FTRACE_README_USER_ACCESS, "*[u]<offset>*"),
+ DEFINE_TYPE(FTRACE_README_USER_ACCESS, "*u]<offset>*"),
DEFINE_TYPE(FTRACE_README_MULTIPROBE_EVENT, "*Create/append/*"),
DEFINE_TYPE(FTRACE_README_IMMEDIATE_VALUE, "*\\imm-value,*"),
};
--
2.17.1
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH v2 2/2] perf: Fix bpf prologue generation
2020-06-09 8:10 [PATCH v2 0/2] perf: Fix bpf prologue generation, uaccess Sumanth Korikkar
2020-06-09 8:10 ` [PATCH v2 1/2] perf: Fix user attribute access in kprobes Sumanth Korikkar
@ 2020-06-09 8:10 ` Sumanth Korikkar
2020-06-09 15:27 ` Arnaldo Carvalho de Melo
1 sibling, 1 reply; 6+ messages in thread
From: Sumanth Korikkar @ 2020-06-09 8:10 UTC (permalink / raw
To: linux-perf-users, acme
Cc: bpf, jolsa, tmricht, heiko.carstens, mhiramat, iii,
Sumanth Korikkar
Issue:
bpf_probe_read is no longer available for architecture which has
overlapping address space. Hence bpf prologue generation fails
Fix:
Use bpf_probe_read_kernel for kernel member access. For user
attribute access in kprobes, use bpf_probe_read_user.
Other:
@user attribute was introduced in commit 1e032f7cfa14 ("perf-probe:
Add user memory access attribute support")
Test:
1. ulimit -l 128 ; ./perf record -e tests/bpf_sched_setscheduler.c
2. cat tests/bpf_sched_setscheduler.c
static void (*bpf_trace_printk)(const char *fmt, int fmt_size, ...) =
(void *) 6;
static int (*bpf_probe_read_user)(void *dst, __u32 size,
const void *unsafe_ptr) = (void *) 112;
static int (*bpf_probe_read_kernel)(void *dst, __u32 size,
const void *unsafe_ptr) = (void *) 113;
SEC("func=do_sched_setscheduler pid policy param->sched_priority@user")
int bpf_func__setscheduler(void *ctx, int err, pid_t pid, int policy,
int param)
{
char fmt[] = "prio: %ld";
bpf_trace_printk(fmt, sizeof(fmt), param);
return 1;
}
char _license[] SEC("license") = "GPL";
int _version SEC("version") = LINUX_VERSION_CODE;
3. ./perf script
sched 305669 [000] 1614458.838675: perf_bpf_probe:func: (2904e508)
pid=261614 policy=2 sched_priority=1
4. cat /sys/kernel/debug/tracing/trace
<...>-309956 [006] .... 1616098.093957: 0: prio: 1
Signed-off-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Reviewed-by: Thomas Richter <tmricht@linux.ibm.com>
---
tools/perf/util/bpf-prologue.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)
diff --git a/tools/perf/util/bpf-prologue.c b/tools/perf/util/bpf-prologue.c
index b020a8678eb9..9887ae09242d 100644
--- a/tools/perf/util/bpf-prologue.c
+++ b/tools/perf/util/bpf-prologue.c
@@ -142,7 +142,8 @@ static int
gen_read_mem(struct bpf_insn_pos *pos,
int src_base_addr_reg,
int dst_addr_reg,
- long offset)
+ long offset,
+ int probeid)
{
/* mov arg3, src_base_addr_reg */
if (src_base_addr_reg != BPF_REG_ARG3)
@@ -159,7 +160,7 @@ gen_read_mem(struct bpf_insn_pos *pos,
ins(BPF_MOV64_REG(BPF_REG_ARG1, dst_addr_reg), pos);
/* Call probe_read */
- ins(BPF_EMIT_CALL(BPF_FUNC_probe_read), pos);
+ ins(BPF_EMIT_CALL(probeid), pos);
/*
* Error processing: if read fail, goto error code,
* will be relocated. Target should be the start of
@@ -241,7 +242,7 @@ static int
gen_prologue_slowpath(struct bpf_insn_pos *pos,
struct probe_trace_arg *args, int nargs)
{
- int err, i;
+ int err, i, probeid;
for (i = 0; i < nargs; i++) {
struct probe_trace_arg *arg = &args[i];
@@ -276,11 +277,16 @@ gen_prologue_slowpath(struct bpf_insn_pos *pos,
stack_offset), pos);
ref = arg->ref;
+ probeid = BPF_FUNC_probe_read_kernel;
while (ref) {
pr_debug("prologue: arg %d: offset %ld\n",
i, ref->offset);
+
+ if (ref->user_access)
+ probeid = BPF_FUNC_probe_read_user;
+
err = gen_read_mem(pos, BPF_REG_3, BPF_REG_7,
- ref->offset);
+ ref->offset, probeid);
if (err) {
pr_err("prologue: failed to generate probe_read function call\n");
goto errout;
--
2.17.1
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH v2 1/2] perf: Fix user attribute access in kprobes
2020-06-09 8:10 ` [PATCH v2 1/2] perf: Fix user attribute access in kprobes Sumanth Korikkar
@ 2020-06-09 15:09 ` Arnaldo Carvalho de Melo
2020-06-09 15:13 ` Arnaldo Carvalho de Melo
0 siblings, 1 reply; 6+ messages in thread
From: Arnaldo Carvalho de Melo @ 2020-06-09 15:09 UTC (permalink / raw
To: Sumanth Korikkar
Cc: Steven Rostedt, linux-perf-users, bpf, jolsa, tmricht,
heiko.carstens, mhiramat, iii
Em Tue, Jun 09, 2020 at 10:10:18AM +0200, Sumanth Korikkar escreveu:
> Issue:
> perf probe -a 'do_sched_setscheduler pid policy
> param->sched_priority@user' did not work before.
>
> Fix:
> Make (perf probe -a 'do_sched_setscheduler pid policy
> param->sched_priority@user') output equivalent to ftrace
> ('p:probe/do_sched_setscheduler _text+517384 pid=%r2:s32 policy=%r3:s32
> sched_priority=+u0(%r4):s32' > kprobe_events)
>
> Other:
> 1. Right now, __match_glob() does not handle [u]<offset>. For now, use
> *u]<offset>.
> 2. @user attribute was introduced in commit 1e032f7cfa14 ("perf-probe:
> Add user memory access attribute support")
>
> Test:
> 1. perf probe -a 'do_sched_setscheduler pid policy
> param->sched_priority@user'
>
> 2 ./perf script
> sched 305669 [000] 1614458.838675: perf_bpf_probe:func: (2904e508)
> pid=261614 policy=2 sched_priority=1
>
> 3. cat /sys/kernel/debug/tracing/trace
> <...>-309956 [006] .... 1616098.093957: 0: prio: 1
Thanks, I'm adding this:
Fixes: 1e032f7cfa14 ("perf-probe: Add user memory access attribute support")
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
So that the stable guys pick this up eventually,
That first hunk with the strcmp() return check could have gone into a
separate patch, but I'll process it as-is for expediency,
- Arnaldo
> Signed-off-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
> Reviewed-by: Thomas Richter <tmricht@linux.ibm.com>
> Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
> ---
> tools/perf/util/probe-event.c | 7 +++++--
> tools/perf/util/probe-file.c | 2 +-
> 2 files changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
> index a08f373d3305..df713a5d1e26 100644
> --- a/tools/perf/util/probe-event.c
> +++ b/tools/perf/util/probe-event.c
> @@ -1575,7 +1575,7 @@ static int parse_perf_probe_arg(char *str, struct perf_probe_arg *arg)
> }
>
> tmp = strchr(str, '@');
> - if (tmp && tmp != str && strcmp(tmp + 1, "user")) { /* user attr */
> + if (tmp && tmp != str && !strcmp(tmp + 1, "user")) { /* user attr */
> if (!user_access_is_supported()) {
> semantic_error("ftrace does not support user access\n");
> return -EINVAL;
> @@ -1995,7 +1995,10 @@ static int __synthesize_probe_trace_arg_ref(struct probe_trace_arg_ref *ref,
> if (depth < 0)
> return depth;
> }
> - err = strbuf_addf(buf, "%+ld(", ref->offset);
> + if (ref->user_access)
> + err = strbuf_addf(buf, "%s%ld(", "+u", ref->offset);
> + else
> + err = strbuf_addf(buf, "%+ld(", ref->offset);
> return (err < 0) ? err : depth;
> }
>
> diff --git a/tools/perf/util/probe-file.c b/tools/perf/util/probe-file.c
> index 8c852948513e..064b63a6a3f3 100644
> --- a/tools/perf/util/probe-file.c
> +++ b/tools/perf/util/probe-file.c
> @@ -1044,7 +1044,7 @@ static struct {
> DEFINE_TYPE(FTRACE_README_PROBE_TYPE_X, "*type: * x8/16/32/64,*"),
> DEFINE_TYPE(FTRACE_README_KRETPROBE_OFFSET, "*place (kretprobe): *"),
> DEFINE_TYPE(FTRACE_README_UPROBE_REF_CTR, "*ref_ctr_offset*"),
> - DEFINE_TYPE(FTRACE_README_USER_ACCESS, "*[u]<offset>*"),
> + DEFINE_TYPE(FTRACE_README_USER_ACCESS, "*u]<offset>*"),
> DEFINE_TYPE(FTRACE_README_MULTIPROBE_EVENT, "*Create/append/*"),
> DEFINE_TYPE(FTRACE_README_IMMEDIATE_VALUE, "*\\imm-value,*"),
> };
> --
> 2.17.1
>
--
- Arnaldo
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v2 1/2] perf: Fix user attribute access in kprobes
2020-06-09 15:09 ` Arnaldo Carvalho de Melo
@ 2020-06-09 15:13 ` Arnaldo Carvalho de Melo
0 siblings, 0 replies; 6+ messages in thread
From: Arnaldo Carvalho de Melo @ 2020-06-09 15:13 UTC (permalink / raw
To: Sumanth Korikkar
Cc: Steven Rostedt, linux-perf-users, bpf, jolsa, tmricht,
heiko.carstens, mhiramat, iii, Linux Kernel Mailing List
Em Tue, Jun 09, 2020 at 12:09:31PM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Tue, Jun 09, 2020 at 10:10:18AM +0200, Sumanth Korikkar escreveu:
> > Issue:
> > perf probe -a 'do_sched_setscheduler pid policy
> > param->sched_priority@user' did not work before.
> >
> > Fix:
> > Make (perf probe -a 'do_sched_setscheduler pid policy
> > param->sched_priority@user') output equivalent to ftrace
> > ('p:probe/do_sched_setscheduler _text+517384 pid=%r2:s32 policy=%r3:s32
> > sched_priority=+u0(%r4):s32' > kprobe_events)
> >
> > Other:
> > 1. Right now, __match_glob() does not handle [u]<offset>. For now, use
> > *u]<offset>.
> > 2. @user attribute was introduced in commit 1e032f7cfa14 ("perf-probe:
> > Add user memory access attribute support")
> >
> > Test:
> > 1. perf probe -a 'do_sched_setscheduler pid policy
> > param->sched_priority@user'
> >
> > 2 ./perf script
> > sched 305669 [000] 1614458.838675: perf_bpf_probe:func: (2904e508)
> > pid=261614 policy=2 sched_priority=1
> >
> > 3. cat /sys/kernel/debug/tracing/trace
> > <...>-309956 [006] .... 1616098.093957: 0: prio: 1
>
> Thanks, I'm adding this:
>
> Fixes: 1e032f7cfa14 ("perf-probe: Add user memory access attribute support")
> Cc: Masami Hiramatsu <mhiramat@kernel.org>
> Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
>
> So that the stable guys pick this up eventually,
>
> That first hunk with the strcmp() return check could have gone into a
> separate patch, but I'll process it as-is for expediency,
I also added this:
ommitter testing:
Before:
# perf probe -a 'do_sched_setscheduler pid policy param->sched_priority@user'
param(type:sched_param) has no member sched_priority@user.
Error: Failed to add events.
# pahole sched_param
struct sched_param {
int sched_priority; /* 0 4 */
/* size: 4, cachelines: 1, members: 1 */
/* last cacheline: 4 bytes */
};
#
After:
# perf probe -a 'do_sched_setscheduler pid policy param->sched_priority@user'
Added new event:
probe:do_sched_setscheduler (on do_sched_setscheduler with pid policy sched_priority=param->sched_priority)
You can now use it in all perf tools, such as:
perf record -e probe:do_sched_setscheduler -aR sleep 1
# cat /sys/kernel/debug/tracing/kprobe_events
p:probe/do_sched_setscheduler _text+1113792 pid=%di:s32 policy=%si:s32 sched_priority=+u0(%dx):s32
#
> - Arnaldo
>
> > Signed-off-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
> > Reviewed-by: Thomas Richter <tmricht@linux.ibm.com>
> > Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
> > ---
> > tools/perf/util/probe-event.c | 7 +++++--
> > tools/perf/util/probe-file.c | 2 +-
> > 2 files changed, 6 insertions(+), 3 deletions(-)
> >
> > diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
> > index a08f373d3305..df713a5d1e26 100644
> > --- a/tools/perf/util/probe-event.c
> > +++ b/tools/perf/util/probe-event.c
> > @@ -1575,7 +1575,7 @@ static int parse_perf_probe_arg(char *str, struct perf_probe_arg *arg)
> > }
> >
> > tmp = strchr(str, '@');
> > - if (tmp && tmp != str && strcmp(tmp + 1, "user")) { /* user attr */
> > + if (tmp && tmp != str && !strcmp(tmp + 1, "user")) { /* user attr */
> > if (!user_access_is_supported()) {
> > semantic_error("ftrace does not support user access\n");
> > return -EINVAL;
> > @@ -1995,7 +1995,10 @@ static int __synthesize_probe_trace_arg_ref(struct probe_trace_arg_ref *ref,
> > if (depth < 0)
> > return depth;
> > }
> > - err = strbuf_addf(buf, "%+ld(", ref->offset);
> > + if (ref->user_access)
> > + err = strbuf_addf(buf, "%s%ld(", "+u", ref->offset);
> > + else
> > + err = strbuf_addf(buf, "%+ld(", ref->offset);
> > return (err < 0) ? err : depth;
> > }
> >
> > diff --git a/tools/perf/util/probe-file.c b/tools/perf/util/probe-file.c
> > index 8c852948513e..064b63a6a3f3 100644
> > --- a/tools/perf/util/probe-file.c
> > +++ b/tools/perf/util/probe-file.c
> > @@ -1044,7 +1044,7 @@ static struct {
> > DEFINE_TYPE(FTRACE_README_PROBE_TYPE_X, "*type: * x8/16/32/64,*"),
> > DEFINE_TYPE(FTRACE_README_KRETPROBE_OFFSET, "*place (kretprobe): *"),
> > DEFINE_TYPE(FTRACE_README_UPROBE_REF_CTR, "*ref_ctr_offset*"),
> > - DEFINE_TYPE(FTRACE_README_USER_ACCESS, "*[u]<offset>*"),
> > + DEFINE_TYPE(FTRACE_README_USER_ACCESS, "*u]<offset>*"),
> > DEFINE_TYPE(FTRACE_README_MULTIPROBE_EVENT, "*Create/append/*"),
> > DEFINE_TYPE(FTRACE_README_IMMEDIATE_VALUE, "*\\imm-value,*"),
> > };
> > --
> > 2.17.1
> >
>
> --
>
> - Arnaldo
--
- Arnaldo
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v2 2/2] perf: Fix bpf prologue generation
2020-06-09 8:10 ` [PATCH v2 2/2] perf: Fix bpf prologue generation Sumanth Korikkar
@ 2020-06-09 15:27 ` Arnaldo Carvalho de Melo
0 siblings, 0 replies; 6+ messages in thread
From: Arnaldo Carvalho de Melo @ 2020-06-09 15:27 UTC (permalink / raw
To: Sumanth Korikkar
Cc: linux-perf-users, bpf, Jiri Olsa, tmricht, heiko.carstens,
mhiramat, iii, Steven Rostedt, Namhyung Kim, Wang Nan,
Linux Kernel Mailing List
Em Tue, Jun 09, 2020 at 10:10:19AM +0200, Sumanth Korikkar escreveu:
> Issue:
> bpf_probe_read is no longer available for architecture which has
> overlapping address space. Hence bpf prologue generation fails
>
> Fix:
> Use bpf_probe_read_kernel for kernel member access. For user
> attribute access in kprobes, use bpf_probe_read_user.
>
> Other:
> @user attribute was introduced in commit 1e032f7cfa14 ("perf-probe:
> Add user memory access attribute support")
>
> Test:
> 1. ulimit -l 128 ; ./perf record -e tests/bpf_sched_setscheduler.c
> 2. cat tests/bpf_sched_setscheduler.c
>
> static void (*bpf_trace_printk)(const char *fmt, int fmt_size, ...) =
> (void *) 6;
> static int (*bpf_probe_read_user)(void *dst, __u32 size,
> const void *unsafe_ptr) = (void *) 112;
> static int (*bpf_probe_read_kernel)(void *dst, __u32 size,
> const void *unsafe_ptr) = (void *) 113;
>
> SEC("func=do_sched_setscheduler pid policy param->sched_priority@user")
> int bpf_func__setscheduler(void *ctx, int err, pid_t pid, int policy,
> int param)
> {
> char fmt[] = "prio: %ld";
> bpf_trace_printk(fmt, sizeof(fmt), param);
> return 1;
> }
>
> char _license[] SEC("license") = "GPL";
> int _version SEC("version") = LINUX_VERSION_CODE;
>
> 3. ./perf script
> sched 305669 [000] 1614458.838675: perf_bpf_probe:func: (2904e508)
> pid=261614 policy=2 sched_priority=1
>
> 4. cat /sys/kernel/debug/tracing/trace
> <...>-309956 [006] .... 1616098.093957: 0: prio: 1
Thanks for providing a detailed set of steps to test your patch, that is
great!
I added this, an alterenative way to test it, combining all the aspects
in one 'perf trace' call:
Committer testing:
I had to add some missing headers in the bpf_sched_setscheduler.c test
proggie, then instead of using record+script I used 'perf trace' to
drive everything in one go:
# cat bpf_sched_setscheduler.c
#include <linux/types.h>
#include <bpf.h>
static void (*bpf_trace_printk)(const char *fmt, int fmt_size, ...) = (void *) 6;
static int (*bpf_probe_read_user)(void *dst, __u32 size, const void *unsafe_ptr) = (void *) 112;
static int (*bpf_probe_read_kernel)(void *dst, __u32 size, const void *unsafe_ptr) = (void *) 113;
SEC("func=do_sched_setscheduler pid policy param->sched_priority@user")
int bpf_func__setscheduler(void *ctx, int err, pid_t pid, int policy, int param)
{
char fmt[] = "prio: %ld";
bpf_trace_printk(fmt, sizeof(fmt), param);
return 1;
}
char _license[] SEC("license") = "GPL";
int _version SEC("version") = LINUX_VERSION_CODE;
#
#
# perf trace -e bpf_sched_setscheduler.c chrt -f 42 sleep 1
0.000 chrt/80125 perf_bpf_probe:func(__probe_ip: -1676607808, policy: 1, sched_priority: 42)
#
And even with backtraces :-)
# perf trace -e bpf_sched_setscheduler.c/max-stack=8/ chrt -f 42 sleep 1
0.000 chrt/79805 perf_bpf_probe:func(__probe_ip: -1676607808, policy: 1, sched_priority: 42)
do_sched_setscheduler ([kernel.kallsyms])
__x64_sys_sched_setscheduler ([kernel.kallsyms])
do_syscall_64 ([kernel.kallsyms])
entry_SYSCALL_64 ([kernel.kallsyms])
__GI___sched_setscheduler (/usr/lib64/libc-2.30.so)
#
- Arnaldo
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2020-06-09 8:10 [PATCH v2 0/2] perf: Fix bpf prologue generation, uaccess Sumanth Korikkar
2020-06-09 8:10 ` [PATCH v2 1/2] perf: Fix user attribute access in kprobes Sumanth Korikkar
2020-06-09 15:09 ` Arnaldo Carvalho de Melo
2020-06-09 15:13 ` Arnaldo Carvalho de Melo
2020-06-09 8:10 ` [PATCH v2 2/2] perf: Fix bpf prologue generation Sumanth Korikkar
2020-06-09 15:27 ` Arnaldo Carvalho de Melo
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