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authorJakub Kicinski <kuba@kernel.org>2021-10-07 07:11:32 -0700
committerJakub Kicinski <kuba@kernel.org>2021-10-07 07:11:33 -0700
commit7671b026bb389a5a01722dd3ecf80b44703e9e84 (patch)
treeb6d9e6f531aaabb40504bb3cd1a9e1aa40c09588 /arch
parent578f3932273ff577f532c54a45248b791089cbf0 (diff)
parentd0c6416bd7091647f6041599f396bfa19ae30368 (diff)
downloadlinux-7671b026bb389a5a01722dd3ecf80b44703e9e84.tar.gz
Merge https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf
Daniel Borkmann says: ==================== pull-request: bpf 2021-10-07 We've added 7 non-merge commits during the last 8 day(s) which contain a total of 8 files changed, 38 insertions(+), 21 deletions(-). The main changes are: 1) Fix ARM BPF JIT to preserve caller-saved regs for DIV/MOD JIT-internal helper call, from Johan Almbladh. 2) Fix integer overflow in BPF stack map element size calculation when used with preallocation, from Tatsuhiko Yasumatsu. 3) Fix an AF_UNIX regression due to added BPF sockmap support related to shutdown handling, from Jiang Wang. 4) Fix a segfault in libbpf when generating light skeletons from objects without BTF, from Kumar Kartikeya Dwivedi. 5) Fix a libbpf memory leak in strset to free the actual struct strset itself, from Andrii Nakryiko. 6) Dual-license bpf_insn.h similarly as we did for libbpf and bpftool, with ACKs from all contributors, from Luca Boccassi. ==================== Link: https://lore.kernel.org/r/20211007135010.21143-1-daniel@iogearbox.net Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/arm/net/bpf_jit_32.c19
1 files changed, 19 insertions, 0 deletions
diff --git a/arch/arm/net/bpf_jit_32.c b/arch/arm/net/bpf_jit_32.c
index a951276f0547..a903b26cde40 100644
--- a/arch/arm/net/bpf_jit_32.c
+++ b/arch/arm/net/bpf_jit_32.c
@@ -36,6 +36,10 @@
* +-----+
* |RSVD | JIT scratchpad
* current ARM_SP => +-----+ <= (BPF_FP - STACK_SIZE + SCRATCH_SIZE)
+ * | ... | caller-saved registers
+ * +-----+
+ * | ... | arguments passed on stack
+ * ARM_SP during call => +-----|
* | |
* | ... | Function call stack
* | |
@@ -63,6 +67,12 @@
*
* When popping registers off the stack at the end of a BPF function, we
* reference them via the current ARM_FP register.
+ *
+ * Some eBPF operations are implemented via a call to a helper function.
+ * Such calls are "invisible" in the eBPF code, so it is up to the calling
+ * program to preserve any caller-saved ARM registers during the call. The
+ * JIT emits code to push and pop those registers onto the stack, immediately
+ * above the callee stack frame.
*/
#define CALLEE_MASK (1 << ARM_R4 | 1 << ARM_R5 | 1 << ARM_R6 | \
1 << ARM_R7 | 1 << ARM_R8 | 1 << ARM_R9 | \
@@ -70,6 +80,8 @@
#define CALLEE_PUSH_MASK (CALLEE_MASK | 1 << ARM_LR)
#define CALLEE_POP_MASK (CALLEE_MASK | 1 << ARM_PC)
+#define CALLER_MASK (1 << ARM_R0 | 1 << ARM_R1 | 1 << ARM_R2 | 1 << ARM_R3)
+
enum {
/* Stack layout - these are offsets from (top of stack - 4) */
BPF_R2_HI,
@@ -464,6 +476,7 @@ static inline int epilogue_offset(const struct jit_ctx *ctx)
static inline void emit_udivmod(u8 rd, u8 rm, u8 rn, struct jit_ctx *ctx, u8 op)
{
+ const int exclude_mask = BIT(ARM_R0) | BIT(ARM_R1);
const s8 *tmp = bpf2a32[TMP_REG_1];
#if __LINUX_ARM_ARCH__ == 7
@@ -495,11 +508,17 @@ static inline void emit_udivmod(u8 rd, u8 rm, u8 rn, struct jit_ctx *ctx, u8 op)
emit(ARM_MOV_R(ARM_R0, rm), ctx);
}
+ /* Push caller-saved registers on stack */
+ emit(ARM_PUSH(CALLER_MASK & ~exclude_mask), ctx);
+
/* Call appropriate function */
emit_mov_i(ARM_IP, op == BPF_DIV ?
(u32)jit_udiv32 : (u32)jit_mod32, ctx);
emit_blx_r(ARM_IP, ctx);
+ /* Restore caller-saved registers from stack */
+ emit(ARM_POP(CALLER_MASK & ~exclude_mask), ctx);
+
/* Save return value */
if (rd != ARM_R0)
emit(ARM_MOV_R(rd, ARM_R0), ctx);