Merge branch 'for-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/bluetoot...

[uclinux-h8/linux.git] / Documentation / networking / filter.txt

diff --git a/Documentation/networking/filter.txt b/Documentation/networking/filter.txt
index 2196b82..b5e060e 100644 (file)
--- a/Documentation/networking/filter.txt
+++ b/Documentation/networking/filter.txt
@@ -464,10 +464,11 @@ breakpoints: 0 1
 JIT compiler
 ------------
 
-The Linux kernel has a built-in BPF JIT compiler for x86_64, SPARC, PowerPC,
-ARM, ARM64, MIPS and s390 and can be enabled through CONFIG_BPF_JIT. The JIT
-compiler is transparently invoked for each attached filter from user space
-or for internal kernel users if it has been previously enabled by root:
+The Linux kernel has a built-in BPF JIT compiler for x86_64, SPARC,
+PowerPC, ARM, ARM64, MIPS, RISC-V and s390 and can be enabled through
+CONFIG_BPF_JIT. The JIT compiler is transparently invoked for each
+attached filter from user space or for internal kernel users if it has
+been previously enabled by root:
 
   echo 1 > /proc/sys/net/core/bpf_jit_enable
 
@@ -603,9 +604,10 @@ got from bpf_prog_create(), and 'ctx' the given context (e.g.
 skb pointer). All constraints and restrictions from bpf_check_classic() apply
 before a conversion to the new layout is being done behind the scenes!
 
-Currently, the classic BPF format is being used for JITing on most 32-bit
-architectures, whereas x86-64, aarch64, s390x, powerpc64, sparc64, arm32 perform
-JIT compilation from eBPF instruction set.
+Currently, the classic BPF format is being used for JITing on most
+32-bit architectures, whereas x86-64, aarch64, s390x, powerpc64,
+sparc64, arm32, riscv (RV64G) perform JIT compilation from eBPF
+instruction set.
 
 Some core changes of the new internal format:
 
@@ -865,7 +867,7 @@ Three LSB bits store instruction class which is one of:
   BPF_STX   0x03          BPF_STX   0x03
   BPF_ALU   0x04          BPF_ALU   0x04
   BPF_JMP   0x05          BPF_JMP   0x05
-  BPF_RET   0x06          [ class 6 unused, for future if needed ]
+  BPF_RET   0x06          BPF_JMP32 0x06
   BPF_MISC  0x07          BPF_ALU64 0x07
 
 When BPF_CLASS(code) == BPF_ALU or BPF_JMP, 4th bit encodes source operand ...
@@ -902,9 +904,9 @@ If BPF_CLASS(code) == BPF_ALU or BPF_ALU64 [ in eBPF ], BPF_OP(code) is one of:
   BPF_ARSH  0xc0  /* eBPF only: sign extending shift right */
   BPF_END   0xd0  /* eBPF only: endianness conversion */
 
-If BPF_CLASS(code) == BPF_JMP, BPF_OP(code) is one of:
+If BPF_CLASS(code) == BPF_JMP or BPF_JMP32 [ in eBPF ], BPF_OP(code) is one of:
 
-  BPF_JA    0x00
+  BPF_JA    0x00  /* BPF_JMP only */
   BPF_JEQ   0x10
   BPF_JGT   0x20
   BPF_JGE   0x30
@@ -912,8 +914,8 @@ If BPF_CLASS(code) == BPF_JMP, BPF_OP(code) is one of:
   BPF_JNE   0x50  /* eBPF only: jump != */
   BPF_JSGT  0x60  /* eBPF only: signed '>' */
   BPF_JSGE  0x70  /* eBPF only: signed '>=' */
-  BPF_CALL  0x80  /* eBPF only: function call */
-  BPF_EXIT  0x90  /* eBPF only: function return */
+  BPF_CALL  0x80  /* eBPF BPF_JMP only: function call */
+  BPF_EXIT  0x90  /* eBPF BPF_JMP only: function return */
   BPF_JLT   0xa0  /* eBPF only: unsigned '<' */
   BPF_JLE   0xb0  /* eBPF only: unsigned '<=' */
   BPF_JSLT  0xc0  /* eBPF only: signed '<' */
@@ -936,8 +938,9 @@ Classic BPF wastes the whole BPF_RET class to represent a single 'ret'
 operation. Classic BPF_RET | BPF_K means copy imm32 into return register
 and perform function exit. eBPF is modeled to match CPU, so BPF_JMP | BPF_EXIT
 in eBPF means function exit only. The eBPF program needs to store return
-value into register R0 before doing a BPF_EXIT. Class 6 in eBPF is currently
-unused and reserved for future use.
+value into register R0 before doing a BPF_EXIT. Class 6 in eBPF is used as
+BPF_JMP32 to mean exactly the same operations as BPF_JMP, but with 32-bit wide
+operands for the comparisons instead.
 
 For load and store instructions the 8-bit 'code' field is divided as: