riscv: Add CFI error handling

With CONFIG_CFI_CLANG, the compiler injects a type preamble immediately
before each function and a check to validate the target function type
before indirect calls:

; type preamble
.word <id>
function:
...
; indirect call check
lw t1, -4(a0)
lui t2, <hi20>
addiw t2, t2, <lo12>
beq t1, t2, .Ltmp0
ebreak
.Ltmp0:
jarl a0

Implement error handling code for the ebreak traps emitted for the
checks. This produces the following oops on a CFI failure (generated
using lkdtm):

[ 21.177245] CFI failure at lkdtm_indirect_call+0x22/0x32 [lkdtm]
(target: lkdtm_increment_int+0x0/0x18 [lkdtm]; expected type: 0x3ad55aca)
[ 21.178483] Kernel BUG [#1]
[ 21.178671] Modules linked in: lkdtm
[ 21.179037] CPU: 1 PID: 104 Comm: sh Not tainted
6.3.0-rc6-00037-g37d5ec6297ab #1
[ 21.179511] Hardware name: riscv-virtio,qemu (DT)
[ 21.179818] epc : lkdtm_indirect_call+0x22/0x32 [lkdtm]
[ 21.180106] ra : lkdtm_CFI_FORWARD_PROTO+0x48/0x7c [lkdtm]
[ 21.180426] epc : ffffffff01387092 ra : ffffffff01386f14 sp : ff20000000453cf0
[ 21.180792] gp : ffffffff81308c38 tp : ff6000000243f080 t0 : ff20000000453b78
[ 21.181157] t1 : 000000003ad55aca t2 : 000000007e0c52a5 s0 : ff20000000453d00
[ 21.181506] s1 : 0000000000000001 a0 : ffffffff0138d170 a1 : ffffffff013870bc
[ 21.181819] a2 : b5fea48dd89aa700 a3 : 0000000000000001 a4 : 0000000000000fff
[ 21.182169] a5 : 0000000000000004 a6 : 00000000000000b7 a7 : 0000000000000000
[ 21.182591] s2 : ff20000000453e78 s3 : ffffffffffffffea s4 : 0000000000000012
[ 21.183001] s5 : ff600000023c7000 s6 : 0000000000000006 s7 : ffffffff013882a0
[ 21.183653] s8 : 0000000000000008 s9 : 0000000000000002 s10: ffffffff0138d878
[ 21.184245] s11: ffffffff0138d878 t3 : 0000000000000003 t4 : 0000000000000000
[ 21.184591] t5 : ffffffff8133df08 t6 : ffffffff8133df07
[ 21.184858] status: 0000000000000120 badaddr: 0000000000000000
cause: 0000000000000003
[ 21.185415] [<ffffffff01387092>] lkdtm_indirect_call+0x22/0x32 [lkdtm]
[ 21.185772] [<ffffffff01386f14>] lkdtm_CFI_FORWARD_PROTO+0x48/0x7c [lkdtm]
[ 21.186093] [<ffffffff01383552>] lkdtm_do_action+0x22/0x34 [lkdtm]
[ 21.186445] [<ffffffff0138350c>] direct_entry+0x128/0x13a [lkdtm]
[ 21.186817] [<ffffffff8033ed8c>] full_proxy_write+0x58/0xb2
[ 21.187352] [<ffffffff801d4fe8>] vfs_write+0x14c/0x33a
[ 21.187644] [<ffffffff801d5328>] ksys_write+0x64/0xd4
[ 21.187832] [<ffffffff801d53a6>] sys_write+0xe/0x1a
[ 21.188171] [<ffffffff80003996>] ret_from_syscall+0x0/0x2
[ 21.188595] Code: 0513 0f65 a303 ffc5 53b7 7e0c 839b 2a53 0363 0073 (9002) 9582
[ 21.189178] ---[ end trace 0000000000000000 ]---
[ 21.189590] Kernel panic - not syncing: Fatal exception

Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com> # ISA bits
Tested-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Link: https://lore.kernel.org/r/20230710183544.999540-12-samitolvanen@google.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

riscv: correct riscv_insn_is_c_jr() and riscv_insn_is_c_jalr()

The instructions c.jr and c.jalr must have rs1 != 0, but
riscv_insn_is_c_jr() and riscv_insn_is_c_jalr() do not check for this. So,
riscv_insn_is_c_jr() can match a reserved encoding, while
riscv_insn_is_c_jalr() can match the c.ebreak instruction.

Rewrite them with check for rs1 != 0.

Signed-off-by: Nam Cao <namcaov@gmail.com>
Reviewed-by: Charlie Jenkins <charlie@rivosinc.com>
Fixes: ec5f90877516 ("RISC-V: Move riscv_insn_is_* macros into a common header")
Link: https://lore.kernel.org/r/20230731183925.152145-1-namcaov@gmail.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

riscv: Allocate user's vector context in the first-use trap

Vector unit is disabled by default for all user processes. Thus, a
process will take a trap (illegal instruction) into kernel at the first
time when it uses Vector. Only after then, the kernel allocates V
context and starts take care of the context for that user process.

Suggested-by: Richard Henderson <richard.henderson@linaro.org>
Link: https://lore.kernel.org/r/3923eeee-e4dc-0911-40bf-84c34aee962d@linaro.org
Signed-off-by: Andy Chiu <andy.chiu@sifive.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230605110724.21391-12-andy.chiu@sifive.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

riscv: Add header include guards to insn.h

Add header include guards to insn.h to prevent repeating declaration of
any identifiers in insn.h.

Fixes: edde5584c7ab ("riscv: Add SW single-step support for KDB")
Signed-off-by: Liao Chang <liaochang1@huawei.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Fixes: c9c1af3f186a ("RISC-V: rename parse_asm.h to insn.h")
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230129094242.282620-1-liaochang1@huawei.com
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

RISC-V: move some stray __RISCV_INSN_FUNCS definitions from kprobes

The __RISCV_INSN_FUNCS originally declared riscv_insn_is_* functions inside
the kprobes implementation. This got moved into a central header in
commit ec5f90877516 ("RISC-V: Move riscv_insn_is_* macros into a common header").

Though it looks like I overlooked two of them, so fix that. FENCE itself is
an instruction defined directly by its own opcode, while the created
riscv_isn_is_system function covers all instructions defined under the SYSTEM
opcode.

Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Heiko Stuebner <heiko.stuebner@vrull.eu>
Link: https://lore.kernel.org/r/20230113211955.3534431-1-heiko@sntech.de
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

riscv: fix jal offsets in patched alternatives

Alternatives live in a different section, so offsets used by jal
instruction will point to wrong locations after the patch got applied.

Similar to arm64, adjust the location to consider that offset.

Co-developed-by: Heiko Stuebner <heiko.stuebner@vrull.eu>
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Heiko Stuebner <heiko.stuebner@vrull.eu>
Link: https://lore.kernel.org/r/20230113212205.3534622-1-heiko@sntech.de
Fixes: 27c653c06505 ("RISC-V: fix auipc-jalr addresses in patched alternatives")
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

RISC-V: add helpers for handling immediates in U-type and I-type pairs

Used together U-type and I-type instructions can for example be used to
generate bigger jumps (i.e. in auipc+jalr pairs) by splitting the value
into an upper immediate (i.e. auipc) and a 12bit immediate (i.e. jalr).

Due to both immediates being considered signed this creates some corner
cases, so add some helper to prevent this from getting duplicated in
different places.

Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Signed-off-by: Heiko Stuebner <heiko.stuebner@vrull.eu>
Link: https://lore.kernel.org/r/20221223221332.4127602-12-heiko@sntech.de
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

RISC-V: add rd reg parsing to insn.h header

Add a macro to allow parsing of the rd register from an instruction.

Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Signed-off-by: Heiko Stuebner <heiko.stuebner@vrull.eu>
Link: https://lore.kernel.org/r/20221223221332.4127602-11-heiko@sntech.de
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

RISC-V: add U-type imm parsing to insn.h header

Similar to other existing types, allow extracting the immediate
for a U-type instruction.

U-type immediates are special in that regard, that the value
in the instruction in bits [31:12] already represents the same
bits of the immediate, so no shifting is required.

U-type immediates are for example used in the auipc instruction,
so these constants make it easier to parse such instructions.

Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Signed-off-by: Heiko Stuebner <heiko.stuebner@vrull.eu>
Link: https://lore.kernel.org/r/20221223221332.4127602-10-heiko@sntech.de
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

RISC-V: rename parse_asm.h to insn.h

The current parse_asm header should become a more centralized place
for everything concerning parsing and constructing instructions.

We already have a header insn-def.h similar to aarch64, so rename
parse_asm.h to insn.h (again similar to aarch64) to show that it's
meant for more than simple instruction parsing.

Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Signed-off-by: Heiko Stuebner <heiko.stuebner@vrull.eu>
Link: https://lore.kernel.org/r/20221223221332.4127602-8-heiko@sntech.de
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>