* [PATCH] bpf: avoid issues with CO-RE and -gtoggle
@ 2024-04-25 17:21 David Faust
2024-04-25 17:46 ` Jose E. Marchesi
0 siblings, 1 reply; 2+ messages in thread
From: David Faust @ 2024-04-25 17:21 UTC (permalink / raw)
To: gcc-patches; +Cc: jose.marchesi
Compiling a BPF program with CO-RE relocations (and BTF) while also
passing -gtoggle led to an inconsistent state where CO-RE support was
enabled but BTF would not be generated, and this was not caught by the
existing option parsing. This led to an ICE when generating the CO-RE
relocation info, since BTF is required for CO-RE.
Update bpf_option_override to avoid this case, and add a few tests for
the interactions of these options.
Tested on x86_64-linux-gnu host for bpf-unknown-none target.
gcc/
* config/bpf/bpf.cc (bpf_option_override): Improve handling of CO-RE
options to avoid issues with -gtoggle.
gcc/testsuite/
* gcc.target/bpf/core-options-1.c: New test.
* gcc.target/bpf/core-options-2.c: Likewise.
* gcc.target/bpf/core-options-3.c: Likewise.
---
gcc/config/bpf/bpf.cc | 7 +++++--
gcc/testsuite/gcc.target/bpf/core-options-1.c | 15 +++++++++++++++
gcc/testsuite/gcc.target/bpf/core-options-2.c | 14 ++++++++++++++
gcc/testsuite/gcc.target/bpf/core-options-3.c | 5 +++++
4 files changed, 39 insertions(+), 2 deletions(-)
create mode 100644 gcc/testsuite/gcc.target/bpf/core-options-1.c
create mode 100644 gcc/testsuite/gcc.target/bpf/core-options-2.c
create mode 100644 gcc/testsuite/gcc.target/bpf/core-options-3.c
diff --git a/gcc/config/bpf/bpf.cc b/gcc/config/bpf/bpf.cc
index 98fb755bb8b..e6ea211a2c6 100644
--- a/gcc/config/bpf/bpf.cc
+++ b/gcc/config/bpf/bpf.cc
@@ -192,7 +192,8 @@ bpf_option_override (void)
init_machine_status = bpf_init_machine_status;
/* BPF CO-RE support requires BTF debug info generation. */
- if (TARGET_BPF_CORE && !btf_debuginfo_p ())
+ if (TARGET_BPF_CORE
+ && (!btf_debuginfo_p () || (debug_info_level < DINFO_LEVEL_NORMAL)))
error ("BPF CO-RE requires BTF debugging information, use %<-gbtf%>");
/* BPF applications always generate .BTF.ext. */
@@ -215,7 +216,9 @@ bpf_option_override (void)
/* -gbtf implies -mcore when using the BPF backend, unless -mno-co-re
is specified. */
- if (btf_debuginfo_p () && !(target_flags_explicit & MASK_BPF_CORE))
+ if (btf_debuginfo_p ()
+ && (debug_info_level >= DINFO_LEVEL_NORMAL)
+ && !(target_flags_explicit & MASK_BPF_CORE))
target_flags |= MASK_BPF_CORE;
/* Determine available features from ISA setting (-mcpu=). */
diff --git a/gcc/testsuite/gcc.target/bpf/core-options-1.c b/gcc/testsuite/gcc.target/bpf/core-options-1.c
new file mode 100644
index 00000000000..7d8c677f239
--- /dev/null
+++ b/gcc/testsuite/gcc.target/bpf/core-options-1.c
@@ -0,0 +1,15 @@
+/* -gbtf for the BPF target should enable CO-RE support automatically. */
+/* { dg-do compile } */
+/* { dg-options "-gbtf" } */
+
+struct A {
+ int x;
+ int y;
+ char c;
+};
+
+int
+foo (struct A *a) {
+ int y = __builtin_preserve_access_index (a->y);
+ return y;
+}
diff --git a/gcc/testsuite/gcc.target/bpf/core-options-2.c b/gcc/testsuite/gcc.target/bpf/core-options-2.c
new file mode 100644
index 00000000000..8f466258e29
--- /dev/null
+++ b/gcc/testsuite/gcc.target/bpf/core-options-2.c
@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+/* { dg-options "-gbtf -gtoggle" } */
+
+struct A {
+ int x;
+ int y;
+ char c;
+};
+
+int
+foo (struct A *a) {
+ int y = __builtin_preserve_access_index (a->y); /* { dg-error "BPF CO-RE is required" } */
+ return y;
+}
diff --git a/gcc/testsuite/gcc.target/bpf/core-options-3.c b/gcc/testsuite/gcc.target/bpf/core-options-3.c
new file mode 100644
index 00000000000..ca32a7c4012
--- /dev/null
+++ b/gcc/testsuite/gcc.target/bpf/core-options-3.c
@@ -0,0 +1,5 @@
+/* This combination of options tries to enable CO-RE without BTF, and should
+ produce an error. */
+/* { dg-do compile } */
+/* { dg-options "-gbtf -gtoggle -mco-re" } */
+/* { dg-excess-errors "BPF CO-RE requires BTF debugging information" } */
--
2.43.0
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH] bpf: avoid issues with CO-RE and -gtoggle
2024-04-25 17:21 [PATCH] bpf: avoid issues with CO-RE and -gtoggle David Faust
@ 2024-04-25 17:46 ` Jose E. Marchesi
0 siblings, 0 replies; 2+ messages in thread
From: Jose E. Marchesi @ 2024-04-25 17:46 UTC (permalink / raw)
To: David Faust; +Cc: gcc-patches
Hi Faust.
OK. Thanks for the patch.
> Compiling a BPF program with CO-RE relocations (and BTF) while also
> passing -gtoggle led to an inconsistent state where CO-RE support was
> enabled but BTF would not be generated, and this was not caught by the
> existing option parsing. This led to an ICE when generating the CO-RE
> relocation info, since BTF is required for CO-RE.
>
> Update bpf_option_override to avoid this case, and add a few tests for
> the interactions of these options.
>
> Tested on x86_64-linux-gnu host for bpf-unknown-none target.
>
> gcc/
> * config/bpf/bpf.cc (bpf_option_override): Improve handling of CO-RE
> options to avoid issues with -gtoggle.
>
> gcc/testsuite/
> * gcc.target/bpf/core-options-1.c: New test.
> * gcc.target/bpf/core-options-2.c: Likewise.
> * gcc.target/bpf/core-options-3.c: Likewise.
> ---
> gcc/config/bpf/bpf.cc | 7 +++++--
> gcc/testsuite/gcc.target/bpf/core-options-1.c | 15 +++++++++++++++
> gcc/testsuite/gcc.target/bpf/core-options-2.c | 14 ++++++++++++++
> gcc/testsuite/gcc.target/bpf/core-options-3.c | 5 +++++
> 4 files changed, 39 insertions(+), 2 deletions(-)
> create mode 100644 gcc/testsuite/gcc.target/bpf/core-options-1.c
> create mode 100644 gcc/testsuite/gcc.target/bpf/core-options-2.c
> create mode 100644 gcc/testsuite/gcc.target/bpf/core-options-3.c
>
> diff --git a/gcc/config/bpf/bpf.cc b/gcc/config/bpf/bpf.cc
> index 98fb755bb8b..e6ea211a2c6 100644
> --- a/gcc/config/bpf/bpf.cc
> +++ b/gcc/config/bpf/bpf.cc
> @@ -192,7 +192,8 @@ bpf_option_override (void)
> init_machine_status = bpf_init_machine_status;
>
> /* BPF CO-RE support requires BTF debug info generation. */
> - if (TARGET_BPF_CORE && !btf_debuginfo_p ())
> + if (TARGET_BPF_CORE
> + && (!btf_debuginfo_p () || (debug_info_level < DINFO_LEVEL_NORMAL)))
> error ("BPF CO-RE requires BTF debugging information, use %<-gbtf%>");
>
> /* BPF applications always generate .BTF.ext. */
> @@ -215,7 +216,9 @@ bpf_option_override (void)
>
> /* -gbtf implies -mcore when using the BPF backend, unless -mno-co-re
> is specified. */
> - if (btf_debuginfo_p () && !(target_flags_explicit & MASK_BPF_CORE))
> + if (btf_debuginfo_p ()
> + && (debug_info_level >= DINFO_LEVEL_NORMAL)
> + && !(target_flags_explicit & MASK_BPF_CORE))
> target_flags |= MASK_BPF_CORE;
>
> /* Determine available features from ISA setting (-mcpu=). */
> diff --git a/gcc/testsuite/gcc.target/bpf/core-options-1.c b/gcc/testsuite/gcc.target/bpf/core-options-1.c
> new file mode 100644
> index 00000000000..7d8c677f239
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/bpf/core-options-1.c
> @@ -0,0 +1,15 @@
> +/* -gbtf for the BPF target should enable CO-RE support automatically. */
> +/* { dg-do compile } */
> +/* { dg-options "-gbtf" } */
> +
> +struct A {
> + int x;
> + int y;
> + char c;
> +};
> +
> +int
> +foo (struct A *a) {
> + int y = __builtin_preserve_access_index (a->y);
> + return y;
> +}
> diff --git a/gcc/testsuite/gcc.target/bpf/core-options-2.c b/gcc/testsuite/gcc.target/bpf/core-options-2.c
> new file mode 100644
> index 00000000000..8f466258e29
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/bpf/core-options-2.c
> @@ -0,0 +1,14 @@
> +/* { dg-do compile } */
> +/* { dg-options "-gbtf -gtoggle" } */
> +
> +struct A {
> + int x;
> + int y;
> + char c;
> +};
> +
> +int
> +foo (struct A *a) {
> + int y = __builtin_preserve_access_index (a->y); /* { dg-error "BPF CO-RE is required" } */
> + return y;
> +}
> diff --git a/gcc/testsuite/gcc.target/bpf/core-options-3.c b/gcc/testsuite/gcc.target/bpf/core-options-3.c
> new file mode 100644
> index 00000000000..ca32a7c4012
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/bpf/core-options-3.c
> @@ -0,0 +1,5 @@
> +/* This combination of options tries to enable CO-RE without BTF, and should
> + produce an error. */
> +/* { dg-do compile } */
> +/* { dg-options "-gbtf -gtoggle -mco-re" } */
> +/* { dg-excess-errors "BPF CO-RE requires BTF debugging information" } */
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2024-04-25 17:21 [PATCH] bpf: avoid issues with CO-RE and -gtoggle David Faust
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