linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Joel Fernandes <joelaf@google.com>
To: linux-kernel@vger.kernel.org
Cc: Chenbo Feng <fengc@google.com>,
	Alison Chaiken <alison@she-devel.com>,
	Juri.Lelli@arm.com, Joel Fernandes <joelaf@google.com>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	netdev@vger.kernel.org (open list:BPF (Safe dynamic programs and
	tools))
Subject: [PATCH RFC v2 4/5] samples/bpf: Fix pt_regs issues when cross-compiling
Date: Mon,  7 Aug 2017 06:06:01 -0700	[thread overview]
Message-ID: <20170807130602.31785-5-joelaf@google.com> (raw)
In-Reply-To: <20170807130602.31785-1-joelaf@google.com>

BPF samples fail to build when cross-compiling for ARM64 because of incorrect
pt_regs param selection. This is because clang defines __x86_64__ and
bpf_headers thinks we're building for x86. Since clang is building for the BPF
target, it shouldn't make assumptions about what target the BPF program is
going to run on. To fix this, lets pass ARCH so the header knows which target
the BPF program is being compiled for and can use the correct pt_regs code.

Signed-off-by: Joel Fernandes <joelaf@google.com>
---
 samples/bpf/Makefile      |  2 +-
 samples/bpf/bpf_helpers.h | 49 +++++++++++++++++++++++++++++++++++++++++------
 2 files changed, 44 insertions(+), 7 deletions(-)

diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index 7591cdd7fe69..8cbcaffe4001 100644
--- a/samples/bpf/Makefile
+++ b/samples/bpf/Makefile
@@ -199,7 +199,7 @@ ASM_STUBS := ${ARCH_ASM_STUBS} -include $(src)/generic_asmstubs.h
 
 CLANG_ARGS = $(NOSTDINC_FLAGS) $(LINUXINCLUDE) $(EXTRA_CFLAGS) \
 		-D__KERNEL__ -Wno-unused-value -Wno-pointer-sign \
-		$(ASM_STUBS) \
+		-D__TARGET_ARCH_$(ARCH) $(ASM_STUBS) \
 		-Wno-compare-distinct-pointer-types \
 		-Wno-gnu-variable-sized-type-not-at-end \
 		-Wno-address-of-packed-member -Wno-tautological-compare \
diff --git a/samples/bpf/bpf_helpers.h b/samples/bpf/bpf_helpers.h
index 67c9c4438e4b..199d2e32703a 100644
--- a/samples/bpf/bpf_helpers.h
+++ b/samples/bpf/bpf_helpers.h
@@ -96,7 +96,42 @@ static int (*bpf_skb_under_cgroup)(void *ctx, void *map, int index) =
 static int (*bpf_skb_change_head)(void *, int len, int flags) =
 	(void *) BPF_FUNC_skb_change_head;
 
+/* Scan the ARCH passed in from ARCH env variable (see Makefile) */
+#if defined(__TARGET_ARCH_x86)
+	#define bpf_target_x86
+	#define bpf_target_defined
+#elif defined(__TARGET_ARCH_s930x)
+	#define bpf_target_s930x
+	#define bpf_target_defined
+#elif defined(__TARGET_ARCH_arm64)
+	#define bpf_target_arm64
+	#define bpf_target_defined
+#elif defined(__TARGET_ARCH_powerpc)
+	#define bpf_target_powerpc
+	#define bpf_target_defined
+#elif defined(__TARGET_ARCH_sparc)
+	#define bpf_target_sparc
+	#define bpf_target_defined
+#else
+	#undef bpf_target_defined
+#endif
+
+/* Fall back to what the compiler says */
+#ifndef bpf_target_defined
 #if defined(__x86_64__)
+	#define bpf_target_x86
+#elif defined(__s390x__)
+	#define bpf_target_s930x
+#elif defined(__aarch64__)
+	#define bpf_target_arm64
+#elif defined(__powerpc__)
+	#define bpf_target_powerpc
+#elif defined(__sparc__)
+	#define bpf_target_sparc
+#endif
+#endif
+
+#if defined(bpf_target_x86)
 
 #define PT_REGS_PARM1(x) ((x)->di)
 #define PT_REGS_PARM2(x) ((x)->si)
@@ -109,7 +144,7 @@ static int (*bpf_skb_change_head)(void *, int len, int flags) =
 #define PT_REGS_SP(x) ((x)->sp)
 #define PT_REGS_IP(x) ((x)->ip)
 
-#elif defined(__s390x__)
+#elif defined(bpf_target_s390x)
 
 #define PT_REGS_PARM1(x) ((x)->gprs[2])
 #define PT_REGS_PARM2(x) ((x)->gprs[3])
@@ -122,7 +157,7 @@ static int (*bpf_skb_change_head)(void *, int len, int flags) =
 #define PT_REGS_SP(x) ((x)->gprs[15])
 #define PT_REGS_IP(x) ((x)->psw.addr)
 
-#elif defined(__aarch64__)
+#elif defined(bpf_target_arm64)
 
 #define PT_REGS_PARM1(x) ((x)->regs[0])
 #define PT_REGS_PARM2(x) ((x)->regs[1])
@@ -135,7 +170,7 @@ static int (*bpf_skb_change_head)(void *, int len, int flags) =
 #define PT_REGS_SP(x) ((x)->sp)
 #define PT_REGS_IP(x) ((x)->pc)
 
-#elif defined(__powerpc__)
+#elif defined(bpf_target_powerpc)
 
 #define PT_REGS_PARM1(x) ((x)->gpr[3])
 #define PT_REGS_PARM2(x) ((x)->gpr[4])
@@ -146,7 +181,7 @@ static int (*bpf_skb_change_head)(void *, int len, int flags) =
 #define PT_REGS_SP(x) ((x)->sp)
 #define PT_REGS_IP(x) ((x)->nip)
 
-#elif defined(__sparc__)
+#elif defined(bpf_target_sparc)
 
 #define PT_REGS_PARM1(x) ((x)->u_regs[UREG_I0])
 #define PT_REGS_PARM2(x) ((x)->u_regs[UREG_I1])
@@ -156,6 +191,8 @@ static int (*bpf_skb_change_head)(void *, int len, int flags) =
 #define PT_REGS_RET(x) ((x)->u_regs[UREG_I7])
 #define PT_REGS_RC(x) ((x)->u_regs[UREG_I0])
 #define PT_REGS_SP(x) ((x)->u_regs[UREG_FP])
+
+/* Should this also be a bpf_target check for the sparc case? */
 #if defined(__arch64__)
 #define PT_REGS_IP(x) ((x)->tpc)
 #else
@@ -164,10 +201,10 @@ static int (*bpf_skb_change_head)(void *, int len, int flags) =
 
 #endif
 
-#ifdef __powerpc__
+#ifdef bpf_target_powerpc
 #define BPF_KPROBE_READ_RET_IP(ip, ctx)		({ (ip) = (ctx)->link; })
 #define BPF_KRETPROBE_READ_RET_IP		BPF_KPROBE_READ_RET_IP
-#elif defined(__sparc__)
+#elif bpf_target_sparc
 #define BPF_KPROBE_READ_RET_IP(ip, ctx)		({ (ip) = PT_REGS_RET(ctx); })
 #define BPF_KRETPROBE_READ_RET_IP		BPF_KPROBE_READ_RET_IP
 #else
-- 
2.14.0.rc1.383.gd1ce394fe2-goog

  parent reply	other threads:[~2017-08-07 13:06 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-08-07 13:05 [PATCH RFC v2 0/5] add arm64 cross compilation support to BPF samples Joel Fernandes
2017-08-07 13:05 ` [PATCH RFC v2 1/5] samples/bpf: Use getppid instead of getpgrp for array map stress Joel Fernandes
2017-08-07 13:05 ` [PATCH RFC v2 2/5] samples/bpf: Enable cross compiler support Joel Fernandes
2017-08-07 13:06 ` [PATCH RFC v2 3/5] samples/bpf: Fix inline asm issues building samples on arm64 Joel Fernandes
2017-08-07 13:15   ` Joel Fernandes
2017-08-07 18:28   ` David Miller
2017-08-08  1:20     ` Joel Fernandes
2017-08-09  3:35       ` David Miller
2017-08-18  6:55         ` Joel Fernandes
2017-08-07 13:06 ` Joel Fernandes [this message]
2017-08-07 13:06 ` [PATCH RFC v2 5/5] samples/bpf: Add documentation on cross compilation Joel Fernandes

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20170807130602.31785-5-joelaf@google.com \
    --to=joelaf@google.com \
    --cc=Juri.Lelli@arm.com \
    --cc=alison@she-devel.com \
    --cc=ast@kernel.org \
    --cc=daniel@iogearbox.net \
    --cc=fengc@google.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=netdev@vger.kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).