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

Fixes: edde5584

 ("riscv: Add SW single-step support for KDB")
Signed-off-by: Liao Chang <liaochang1@huawei.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Fixes: c9c1af3f

 ("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>

Björn Töpel <bjorn@kernel.org> says:

From: Björn Töpel <bjorn@rivosinc.com>

RISC-V does not dump faulting instructions in the oops handler. This
series adds "Code:" dumps to the oops output together with
scripts/decodecode support.

* b4-shazam-merge:
  scripts/decodecode: Add support for RISC-V
  riscv: Add instruction dump to RISC-V splats

Link: https://lore.kernel.org/r/20230119074738.708301-1-bjorn@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

If we patched auipc + jalr pair, we'd better proceed one more
instruction. Andrew pointed out "There's not a problem now, since
we're only adding a fixup for jal, not jalr, but we should
future-proof this and there's no reason to revisit an already fixed-up
instruction anyway."

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Suggested-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Link: https://lore.kernel.org/r/20230115162811.3146-1-jszhang@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

Jisheng Zhang <jszhang@kernel.org> says:

This series tries to improve link time handling of riscv:
patch1 adds the missing RUNTIME_DISCARD_EXIT as suggested by Masahiro.

Similar as other architectures such as x86, arm64 and so on, enable
ARCH_WANT_LD_ORPHAN_WARN to enable linker orphan warnings to prevent
from missing any new sections in future. So the following two patches
are preparation ones, and the last patch finally selects
ARCH_WANT_LD_ORPHAN_WARN

* b4-shazam-merge:
  riscv: select ARCH_WANT_LD_ORPHAN_WARN for !XIP_KERNEL
  riscv: vmlinux.lds.S: explicitly catch .init.bss sections from EFI stub
  riscv: vmlinux.lds.S: explicitly catch .riscv.attributes sections
  riscv: vmlinux.lds.S: explicitly catch .rela.dyn symbols
  riscv: lds: define RUNTIME_DISCARD_EXIT

Link: https://lore.kernel.org/r/20230119155417.2600-1-jszhang@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

While working on something else, I noticed that the kernel would start
accepting interrupts again after crashing in an interrupt handler. Since
the kernel is already in inconsistent state, enabling interrupts is
dangerous and opens up risk of kernel state deteriorating further.
Interrupts do get enabled via what looks like an unintended side effect of
spin_unlock_irq, so switch to the more cautious
spin_lock_irqsave/spin_unlock_irqrestore instead.

Fixes: 76d2a049

 ("RISC-V: Init and Halt Code")
Signed-off-by: Mattias Nissler <mnissler@rivosinc.com>
Reviewed-by: Björn Töpel <bjorn@kernel.org>
Link: https://lore.kernel.org/r/20230215144828.3370316-1-mnissler@rivosinc.com
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

Commit 21855cac ("riscv/mm: Prevent kernel module to access user
memory without uaccess routines") added early exits/deaths for page
faults stemming from accesses to user-space without using proper
uaccess routines (where sstatus.SUM is set).

Unfortunatly, this is too strict for some BPF programs, which relies
on BPF exhandler fixups. These BPF programs loads "BTF pointers". A
BTF pointers could either be a valid kernel pointer or NULL, but not a
userspace address.

Resolve the problem by calling the fixup handler in the early exit
path.

Fixes: 21855cac

 ("riscv/mm: Prevent kernel module to access user memory without uaccess routines")
Signed-off-by: Björn Töpel <bjorn@rivosinc.com>
Link: https://lore.kernel.org/r/20230214162515.184827-1-bjorn@kernel.org
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

Guenter reported a splat during boot, that Samuel pointed out was the
lockdep assertion failing in patch_insn_write():

WARNING: CPU: 0 PID: 0 at arch/riscv/kernel/patch.c:63 patch_insn_write+0x222/0x2f6
epc : patch_insn_write+0x222/0x2f6
 ra : patch_insn_write+0x21e/0x2f6
epc : ffffffff800068c6 ra : ffffffff800068c2 sp : ffffffff81803df0
 gp : ffffffff81a1ab78 tp : ffffffff81814f80 t0 : ffffffffffffe000
 t1 : 0000000000000001 t2 : 4c45203a76637369 s0 : ffffffff81803e40
 s1 : 0000000000000004 a0 : 0000000000000000 a1 : ffffffffffffffff
 a2 : 0000000000000004 a3 : 0000000000000000 a4 : 0000000000000001
 a5 : 0000000000000000 a6 : 0000000000000000 a7 : 0000000052464e43
 s2 : ffffffff80b4889c s3 : 000000000000082c s4 : ffffffff80b48828
 s5 : 0000000000000828 s6 : ffffffff8131a0a0 s7 : 0000000000000fff
 s8 : 0000000008000200 s9 : ffffffff8131a520 s10: 0000000000000018
 s11: 000000000000000b t3 : 0000000000000001 t4 : 000000000000000d
 t5 : ffffffffd8180000 t6 : ffffffff81803bc8
status: 0000000200000100 badaddr: 0000000000000000 cause: 0000000000000003
[<ffffffff800068c6>] patch_insn_write+0x222/0x2f6
[<ffffffff80006a36>] patch_text_nosync+0xc/0x2a
[<ffffffff80003b86>] riscv_cpufeature_patch_func+0x52/0x98
[<ffffffff80003348>] _apply_alternatives+0x46/0x86
[<ffffffff80c02d36>] apply_boot_alternatives+0x3c/0xfa
[<ffffffff80c03ad8>] setup_arch+0x584/0x5b8
[<ffffffff80c0075a>] start_kernel+0xa2/0x8f8

This issue was exposed by 702e6455 ("riscv: fpu: switch has_fpu() to
riscv_has_extension_likely()"), as it is the patching in has_fpu() that
triggers the splats in Guenter's report.

Take the text_mutex before doing any code patching to satisfy lockdep.

Fixes: ff689fd2 ("riscv: add RISC-V Svpbmt extension support")
Fixes: a35707c3 ("riscv: add memory-type errata for T-Head")
Fixes: 1a0e5dbd

 ("riscv: sifive: Add SiFive alternative ports")
Reported-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/all/20230212154333.GA3760469@roeck-us.net/
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Samuel Holland <samuel@sholland.org>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20230212194735.491785-1-conor@kernel.org
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

While the comment above the ISA extension ID definitions says
"Entries are sorted alphabetically.", this stopped being good
advice with commit d8a3d8a7

 ("riscv: hwcap: make ISA extension
ids can be used in asm"), as we now use macros instead of enums.
Reshuffling defines is error-prone, so, since they don't need to be
in any particular order, change the advice to just adding new
extensions at the bottom. Also, take the opportunity to change
spaces to tabs, merge three comments into one, and move the base
and max defines into more logical locations wrt the ID definitions.

Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230209123636.123537-1-ajones@ventanamicro.com
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

As Andrew reported,
    Zb* comes after Zi* according 27.11 "Subset Naming Convention"
so fix the ordering accordingly.

Reported-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Heiko Stuebner <heiko.stuebner@vrull.eu>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Tested-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230208225328.1636017-2-heiko@sntech.de
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

Runtime code patching must be done at a naturally aligned address, or we
may execute on a partial instruction.

We have encountered problems traced back to static jump functions during
the test. We switched the tracer randomly for every 1~5 seconds on a
dual-core QEMU setup and found the kernel sucking at a static branch
where it jumps to itself.

The reason is that the static branch was 2-byte but not 4-byte aligned.
Then, the kernel would patch the instruction, either J or NOP, with two
half-word stores if the machine does not have efficient unaligned
accesses. Thus, moments exist where half of the NOP mixes with the other
half of the J when transitioning the branch. In our particular case, on
a little-endian machine, the upper half of the NOP was mixed with the
lower part of the J when enabling the branch, resulting in a jump that
jumped to itself. Conversely, it would result in a HINT instruction when
disabling the branch, but it might not be observable.

ARM64 does not have this problem since all instructions must be 4-byte
aligned.

Fixes: ebc00dde

 ("riscv: Add jump-label implementation")
Link: https://lore.kernel.org/linux-riscv/20220913094252.3555240-6-andy.chiu@sifive.com/
Reviewed-by: Greentime Hu <greentime.hu@sifive.com>
Signed-off-by: Andy Chiu <andy.chiu@sifive.com>
Signed-off-by: Guo Ren <guoren@kernel.org>
Link: https://lore.kernel.org/r/20230206090440.1255001-1-guoren@kernel.org
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

The recent refactoring led to us leaking some HWCAP bits to userspace
that didn't make much sense.  With any luck we'll have a better scheme
soon, but for now just mask off those bits to avoid polluting userspace.

Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230202233832.11036-1-palmer@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

This is a partial revert of the commit 4bd1d80e ("riscv: mm: notify
remote harts about mmu cache updates"). Original commit included two
loosely related changes serving the same purpose of fixing stale TLB
entries causing user-space application crash:
- introduce deferred per-ASID TLB flush for CPUs not running the task
- switch to per-ASID TLB flush on all CPUs running the task in update_mmu_cache

According to report and discussion in [1], the second part caused a
regression on Renesas RZ/Five SoC. For now restore the old behavior
of the update_mmu_cache.

[1] https://lore.kernel.org/linux-riscv/20220829205219.283543-1-geomatsi@gmail.com/

Fixes: 4bd1d80e

 ("riscv: mm: notify remote harts about mmu cache updates")
Reported-by: "Lad, Prabhakar" <prabhakar.csengg@gmail.com>
Signed-off-by: Sergey Matyukevich <sergey.matyukevich@syntacore.com>
Link: trailer, so that it can be parsed with git's trailer functionality?
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230129211818.686557-1-geomatsi@gmail.com
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

RISC-V has some GNU disassembly quirks, e.g. it requires '-D' to
properly disassemble .2byte directives similar to Arm [1]. Further,
GNU objdump groups RISC-V instruction by 2 or 4 byte chunks, instead
doing byte-for-byte.

Add the required switches, and translate from short/word to bytes when
ARCH is "riscv".

An example how to invoke decodecode for RISC-V:
  $ echo 'Code: bf45 f793 1007 f7d9 50ef 37af d541 b7d9 7097 00c8 (80e7)
  6140' | AFLAGS="-march=rv64imac_zicbom_zihintpause"  \
  ARCH=riscv CROSS_COMPILE=riscv64-linux-gnu- ./scripts/decodecode
  Code: bf45 f793 1007 f7d9 50ef 37af d541 b7d9 7097 00c8 (80e7) 6140
  All code
  ========
     0:   bf45                    c.j     0xffffffffffffffb0
     2:   1007f793                andi    a5,a5,256
     6:   f7d9                    c.bnez  a5,0xffffffffffffff94
     8:   37af50ef                jal     ra,0xf5382
     c:   d541                    c.beqz  a0,0xffffffffffffff94
     e:   b7d9                    c.j     0xffffffffffffffd4
    10:   00c87097                auipc   ra,0xc87
    14:*  614080e7                jalr    ra,1556(ra) # 0xc87624          <-- trapping instruction

  Code starting with the faulting instruction
  ===========================================
     0:   614080e7                jalr    ra,1556(ra)

[1] https://sourceware.org/bugzilla/show_bug.cgi?id=10263

Signed-off-by: Björn Töpel <bjorn@rivosinc.com>
Tested-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Link: https://lore.kernel.org/r/20230119074738.708301-3-bjorn@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

Add instruction dump (Code:) output to RISC-V splats. Dump 16b
parcels.

An example:
  Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
  Oops [#1]
  Modules linked in:
  CPU: 0 PID: 1 Comm: swapper/0 Not tainted 6.2.0-rc3-00302-g840ff44c571d-dirty #27
  Hardware name: riscv-virtio,qemu (DT)
  epc : kernel_init+0xc8/0x10e
   ra : kernel_init+0x70/0x10e
  epc : ffffffff80bd9a40 ra : ffffffff80bd99e8 sp : ff2000000060bec0
   gp : ffffffff81730b28 tp : ff6000007ff00000 t0 : 7974697275636573
   t1 : 0000000000000000 t2 : 3030303270393d6e s0 : ff2000000060bee0
   s1 : ffffffff81732028 a0 : 0000000000000000 a1 : ff60000080dd1780
   a2 : 0000000000000002 a3 : ffffffff8176a470 a4 : 0000000000000000
   a5 : 000000000000000a a6 : 0000000000000081 a7 : ff60000080dd1780
   s2 : 0000000000000000 s3 : 0000000000000000 s4 : 0000000000000000
   s5 : 0000000000000000 s6 : 0000000000000000 s7 : 0000000000000000
   s8 : 0000000000000000 s9 : 0000000000000000 s10: 0000000000000000
   s11: 0000000000000000 t3 : ffffffff81186018 t4 : 0000000000000022
   t5 : 000000000000003d t6 : 0000000000000000
  status: 0000000200000120 badaddr: 0000000000000000 cause: 000000000000000f
  [<ffffffff80003528>] ret_from_exception+0x0/0x16
  Code: 862a d179 608c a517 0069 0513 2be5 d0ef db2e 47a9 (c11c) a517
  ---[ end trace 0000000000000000 ]---
  Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
  SMP: stopping secondary CPUs
  ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b ]---

Signed-off-by: Björn Töpel <bjorn@rivosinc.com>
Link: https://lore.kernel.org/r/20230119074738.708301-2-bjorn@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

Now, after that all the sections are explicitly described and
declared in vmlinux.lds.S, we can enable ld orphan warnings for
!XIP_KERNEL to prevent from missing any new sections in future.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230119155417.2600-6-jszhang@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

When enabling linker orphan section warning, I got warnings similar as
below:
ld.lld: warning:
./drivers/firmware/efi/libstub/lib.a(efi-stub-helper.stub.o):(.init.bss)
is being placed in '.init.bss'

Catch the sections so that we can enable linker orphan section warning.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Link: https://lore.kernel.org/r/20230119155417.2600-5-jszhang@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

When enabling linker orphan section warning, I got warnings similar as
below:
riscv64-linux-gnu-ld: warning: orphan section `.riscv.attributes' from
`init/main.o' being placed in section `.riscv.attributes'

While I don't see any usage of .riscv.attributes sections' in kernel
now, just catch the sections so that we can enable linker orphan
section warning.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Link: https://lore.kernel.org/r/20230119155417.2600-4-jszhang@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

When enabling linker orphan section warning, I got warnings similar as
below:
riscv64-linux-gnu-ld: warning: orphan section `.rela.text' from
`init/main.o' being placed in section `.rela.dyn'

Use the approach similar as ARM64 does and declare it in vmlinux.lds.S

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Link: https://lore.kernel.org/r/20230119155417.2600-3-jszhang@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

riscv discards .exit.* sections at run-time but doesn't define
RUNTIME_DISCARD_EXIT. However, the .exit.* sections are still allocated
and kept even if the generic DISCARDS would discard the sections due
to missing RUNTIME_DISCARD_EXIT, because the DISCARD sits at the end of
the linker script. Add the missing RUNTIME_DISCARD_EXIT define so that
it still works if we move DISCARD up or even at the beginning of the
linker script.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Suggested-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230119155417.2600-2-jszhang@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

The __RISCV_INSN_FUNCS originally declared riscv_insn_is_* functions inside
the kprobes implementation. This got moved into a central header in
commit ec5f9087

 ("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>

guoren@kernel.org <guoren@kernel.org> says:

From: Guo Ren <guoren@linux.alibaba.com>

The previous ftrace detour implementation fc76b8b8011 ("riscv: Using
PATCHABLE_FUNCTION_ENTRY instead of MCOUNT") contain three problems.

 - The most horrible bug is preemption panic which found by Andy [1].
   Let's disable preemption for ftrace first, and Andy could continue
   the ftrace preemption work.
 - The "-fpatchable-function-entry= CFLAG" wasted code size
   !RISCV_ISA_C.
 - The ftrace detour implementation wasted code size.
 - When livepatching, the trampoline (ftrace_regs_caller) would not
   return to <func_prolog+12> but would rather jump to the new function.
   So, "REG_L ra, -SZREG(sp)" would not run and the original return
   address would not be restored. The kernel is likely to hang or crash
   as a result. (Found by Evgenii Shatokhin [4])

[Palmer: The first three patches in this series are pretty concrete
fixes, so I'm pulling them ahead of the rest of the series.]

* b4-shazam-merge:
  riscv: ftrace: Reduce the detour code size to half
  riscv: ftrace: Remove wasted nops for !RISCV_ISA_C
  riscv: ftrace: Fixup panic by disabling preemption

Link: https://lore.kernel.org/r/20230112090603.1295340-1-guoren@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

Use a temporary register to reduce the size of detour code from 16 bytes to
8 bytes. The previous implementation is from 'commit afc76b8b

 ("riscv:
Using PATCHABLE_FUNCTION_ENTRY instead of MCOUNT")'.

Before the patch:
<func_prolog>:
 0: REG_S  ra, -SZREG(sp)
 4: auipc  ra, ?
 8: jalr   ?(ra)
12: REG_L  ra, -SZREG(sp)
 (func_boddy)

After the patch:
<func_prolog>:
 0: auipc  t0, ?
 4: jalr   t0, ?(t0)
 (func_boddy)

This patch not just reduces the size of detour code, but also fixes an
important issue:

An Ftrace callback registered with FTRACE_OPS_FL_IPMODIFY flag can
actually change the instruction pointer, e.g. to "replace" the given
kernel function with a new one, which is needed for livepatching, etc.

In this case, the trampoline (ftrace_regs_caller) would not return to
<func_prolog+12> but would rather jump to the new function. So, "REG_L
ra, -SZREG(sp)" would not run and the original return address would not
be restored. The kernel is likely to hang or crash as a result.

This can be easily demonstrated if one tries to "replace", say,
cmdline_proc_show() with a new function with the same signature using
instruction_pointer_set(&fregs->regs, new_func_addr) in the Ftrace
callback.

Link: https://lore.kernel.org/linux-riscv/20221122075440.1165172-1-suagrfillet@gmail.com/
Link: https://lore.kernel.org/linux-riscv/d7d5730b-ebef-68e5-5046-e763e1ee6164@yadro.com/
Co-developed-by: Song Shuai <suagrfillet@gmail.com>
Signed-off-by: Song Shuai <suagrfillet@gmail.com>
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@kernel.org>
Cc: Evgenii Shatokhin <e.shatokhin@yadro.com>
Reviewed-by: Evgenii Shatokhin <e.shatokhin@yadro.com>
Link: https://lore.kernel.org/r/20230112090603.1295340-4-guoren@kernel.org
Cc: stable@vger.kernel.org
Fixes: 10626c32

 ("riscv/ftrace: Add basic support")
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

When CONFIG_RISCV_ISA_C=n, -fpatchable-function-entry=8 would generate
more nops than we expect. Because it treat nop opcode as 0x00000013
instead of 0x0001.

Dump of assembler code for function dw_pcie_free_msi:
   0xffffffff806fce94 <+0>:     sd      ra,-8(sp)
   0xffffffff806fce98 <+4>:     auipc   ra,0xff90f
   0xffffffff806fce9c <+8>:     jalr    -684(ra) # 0xffffffff8000bbec
<ftrace_caller>
   0xffffffff806fcea0 <+12>:    ld      ra,-8(sp)
   0xffffffff806fcea4 <+16>:    nop /* wasted */
   0xffffffff806fcea8 <+20>:    nop /* wasted */
   0xffffffff806fceac <+24>:    nop /* wasted */
   0xffffffff806fceb0 <+28>:    nop /* wasted */
   0xffffffff806fceb4 <+0>:     addi    sp,sp,-48
   0xffffffff806fceb8 <+4>:     sd      s0,32(sp)
   0xffffffff806fcebc <+8>:     sd      s1,24(sp)
   0xffffffff806fcec0 <+12>:    sd      s2,16(sp)
   0xffffffff806fcec4 <+16>:    sd      s3,8(sp)
   0xffffffff806fcec8 <+20>:    sd      ra,40(sp)
   0xffffffff806fcecc <+24>:    addi    s0,sp,48

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@kernel.org>
Link: https://lore.kernel.org/r/20230112090603.1295340-3-guoren@kernel.org
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

In RISCV, we must use an AUIPC + JALR pair to encode an immediate,
forming a jump that jumps to an address over 4K. This may cause errors
if we want to enable kernel preemption and remove dependency from
patching code with stop_machine(). For example, if a task was switched
out on auipc. And, if we changed the ftrace function before it was
switched back, then it would jump to an address that has updated 11:0
bits mixing with previous XLEN:12 part.

p: patched area performed by dynamic ftrace
ftrace_prologue:
p|      REG_S   ra, -SZREG(sp)
p|      auipc   ra, 0x? ------------> preempted
					...
				change ftrace function
					...
p|      jalr    -?(ra) <------------- switched back
p|      REG_L   ra, -SZREG(sp)
func:
	xxx
	ret

Fixes: afc76b8b

 ("riscv: Using PATCHABLE_FUNCTION_ENTRY instead of MCOUNT")
Signed-off-by: Andy Chiu <andy.chiu@sifive.com>
Signed-off-by: Guo Ren <guoren@kernel.org>
Link: https://lore.kernel.org/r/20230112090603.1295340-2-guoren@kernel.org
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

Conor Dooley <conor@kernel.org> says:

From: Conor Dooley <conor.dooley@microchip.com>

I've yoinked patch 1 from Drew's series adding support for Zicboz &
attached two more patches here that remove the need for, and then drop
the toolchain support checks for Zicbom. The goal is to remove the need
for checking the presence of toolchain Zicbom support in the work being
done to support non instruction based CMOs [1].

I've tested compliation on a number of different configurations with
the Zicbom config option enabled. The important ones to call out I
guess are:
- clang/llvm 14 w/ LLVM=1 which doesn't support Zicbom atm.
- gcc 11 w/ binutils 2.37 which doesn't support Zicbom atm either.
- clang/llvm 15 w/ LLVM=1 BUT with binutils 2.37's ld. This is the
  configuration that prompted adding the LD checks as cc/as supports
  Zicbom, but ld doesn't [2].
- gcc 12 w/ binutils 2.39 & clang 15 w/ LLVM=1, both of these supported
  Zicbom before and still do.

I also checked building the THEAD errata etc with
CONFIG_RISCV_ISA_ZICBOM disabled, and there were no build issues there
either.

* b4-shazam-merge:
  RISC-V: remove toolchain version checks for Zicbom
  RISC-V: replace cbom instructions with an insn-def
  RISC-V: insn-def: Add I-type insn-def

Link: https://lore.kernel.org/r/20230108163356.3063839-1-conor@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

Commit b8c86872

 ("riscv: fix detection of toolchain Zicbom
support") fixed building on systems where Zicbom was supported by the
compiler/assembler but not by the linker in an easily backportable
manner.
Now that the we have insn-defs for the 3 instructions, toolchain support
is no longer required for Zicbom.
Stop emitting "_zicbom" in -march when Zicbom is enabled & drop the
version checks entirely.

Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Link: https://lore.kernel.org/r/20230108163356.3063839-4-conor@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

Using the cbom instructions directly in ALT_CMO_OP, requires toolchain
support for the instructions. Using an insn-def will allow for removal
of toolchain version checks in the build system & simplification of the
proposed [1] function-based CMO scheme.

Link: https://lore.kernel.org/linux-riscv/fb3b34ae-e35e-4dc2-a8f4-19984a2f58a8@app.fastmail.com/ [1]
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Link: https://lore.kernel.org/r/20230108163356.3063839-3-conor@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

CBO instructions use the I-type of instruction format where
the immediate is used to identify the CBO instruction type.
Add I-type instruction encoding support to insn-def.

Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Link: https://lore.kernel.org/r/20230108163356.3063839-2-conor@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

Conor Dooley <conor@kernel.org> says:

From: Conor Dooley <conor.dooley@microchip.com>

Ever since RISC-V starting using generic arch topology code, the code
paths for cpu-capacity have been there but there's no binding defined to
actually convey the information. Defining the same property as used on
arm seems to be the only logical thing to do, so do it.

[Palmer: This is on top of the fix required to make it work, which
itself wasn't merged until late in the 6.2 cycle and thus pulls in
various other fixes.]

* b4-shazam-merge:
  dt-bindings: riscv: add a capacity-dmips-mhz cpu property
  dt-bindings: arm: move cpu-capacity to a shared loation
  riscv: Move call to init_cpu_topology() to later initialization stage
  riscv/kprobe: Fix instruction simulation of JALR
  riscv: fix -Wundef warning for CONFIG_RISCV_BOOT_SPINWAIT
  MAINTAINERS: add an IRC entry for RISC-V
  RISC-V: fix compile error from deduplicated __ALTERNATIVE_CFG_2
  dt-bindings: riscv: fix single letter canonical order
  dt-bindings: riscv: fix underscore requirement for multi-letter extensions
  riscv: uaccess: fix type of 0 variable on error in get_user()
  riscv, kprobes: Stricter c.jr/c.jalr decoding

Link: https://lore.kernel.org/r/20230104180513.1379453-1-conor@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

Since commit 03f11f03

 ("RISC-V: Parse cpu topology during boot.")
RISC-V has used the generic arch topology code, which provides for
disparate CPU capacities. We never defined a binding to acquire this
information from the DT though, so document the one already used by the
generic arch topology code: "capacity-dmips-mhz".

Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Ley Foon Tan <leyfoon.tan@starfivetech.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20230104180513.1379453-3-conor@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

RISC-V uses the same generic topology code as arm64 & while there
currently exists no binding for cpu-capacity on RISC-V, the code paths
can be hit if the property is present.

Move the documentation of cpu-capacity to a shared location, ahead of
defining a binding for capacity-dmips-mhz on RISC-V. Update some
references to this document in the process.

Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Ley Foon Tan <leyfoon.tan@starfivetech.com>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Yanteng Si <siyanteng@loongson.cn>
Link: https://lore.kernel.org/r/20230104180513.1379453-2-conor@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

Commit 4bf88607 ("riscv: cpufeature: extend
riscv_cpufeature_patch_func to all ISA extensions") switched ISA
extension alternatives to use the RISCV_ISA_EXT_* macros instead of
CPUFEATURE_*. This was mismerged when applied on top of the Zbb series,
so the Zbb alternatives referenced the wrong errata ID values.

Fixes: 9daca9a5

 ("Merge patch series "riscv: improve boot time isa extensions handling"")
Signed-off-by: Samuel Holland <samuel@sholland.org>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Guo Ren <guoren@kernel.org>
Tested-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230212021534.59121-3-samuel@sholland.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

Now that the text to patch is located using a relative offset from the
alternative entry, the text address should be computed without applying
the kernel mapping offset, both before and after VM setup.

Fixes: 8d23e94a

 ("riscv: switch to relative alternative entries")
Signed-off-by: Samuel Holland <samuel@sholland.org>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Guo Ren <guoren@kernel.org>
Reviewed-by: Jisheng Zhang <jszhang@kernel.org>
Tested-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230212021534.59121-2-samuel@sholland.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

Selects should be sorted alphanumerically, and were tidied up originally
by Palmer in commit e8c7ef7d ("RISC-V: Sort select statements
alphanumerically") since then, things have gotten out of order again.
Fish RMK's original script out of commit b1b3f49c

 ("ARM: config:
sort select statements alphanumerically") and do some spring cleaning.

Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Acked-by: Björn Töpel <bjorn@rivosinc.com>
Link: https://lore.kernel.org/r/20221219172836.134709-1-conor@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

When adding the ISA string ordering rules, I didn't sufficiently indent
one of the list items.

Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/linux-doc/202301300743.bp7Dpazv-lkp@intel.com/
Fixes: f07b2b3f

 ("Documentation: riscv: add a section about ISA string ordering in /proc/cpuinfo")
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>
Link: https://lore.kernel.org/r/20230129235701.2393241-1-conor@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

Jisheng Zhang <jszhang@kernel.org> says:

Generally, riscv ISA extensions are fixed for any specific hardware
platform, so a hart's features won't change after booting, this
chacteristic makes it straightforward to use a static branch to check
a specific ISA extension is supported or not to optimize performance.

However, some ISA extensions such as SVPBMT and ZICBOM are handled
via. the alternative sequences.

Basically, for ease of maintenance, we prefer to use static branches
in C code, but recently, Samuel found that the static branch usage in
cpu_relax() breaks building with CONFIG_CC_OPTIMIZE_FOR_SIZE[1]. As
Samuel pointed out, "Having a static branch in cpu_relax() is
problematic because that function is widely inlined, including in some
quite complex functions like in the VDSO. A quick measurement shows
this static branch is responsible by itself for around 40% of the jump
table."

Samuel's findings pointed out one of a few downsides of static branches
usage in C code to handle ISA extensions detected at boot time:
static branch's metadata in the __jump_table section, which is not
discarded after ISA extensions are finalized, wastes some space.

I want to try to solve the issue for all possible dynamic handling of
ISA extensions at boot time. Inspired by Mark[2], this patch introduces
riscv_has_extension_*() helpers, which work like static branches but
are patched using alternatives, thus the metadata can be freed after
patching.

[1]https://lore.kernel.org/linux-riscv/20220922060958.44203-1-samuel@sholland.org/
[2]https://lore.kernel.org/linux-arm-kernel/20220912162210.3626215-8-mark.rutland@arm.com/
[3]https://lore.kernel.org/linux-riscv/20221130225614.1594256-1-heiko@sntech.de/

* b4-shazam-merge:
  riscv: remove riscv_isa_ext_keys[] array and related usage
  riscv: KVM: Switch has_svinval() to riscv_has_extension_unlikely()
  riscv: cpu_relax: switch to riscv_has_extension_likely()
  riscv: alternative: patch alternatives in the vDSO
  riscv: switch to relative alternative entries
  riscv: module: Add ADD16 and SUB16 rela types
  riscv: module: move find_section to module.h
  riscv: fpu: switch has_fpu() to riscv_has_extension_likely()
  riscv: introduce riscv_has_extension_[un]likely()
  riscv: cpufeature: extend riscv_cpufeature_patch_func to all ISA extensions
  riscv: hwcap: make ISA extension ids can be used in asm
  riscv: cpufeature: detect RISCV_ALTERNATIVES_EARLY_BOOT earlier
  riscv: move riscv_noncoherent_supported() out of ZICBOM probe

Link: https://lore.kernel.org/r/20230128172856.3814-1-jszhang@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

All users have switched to riscv_has_extension_*, remove unused
definitions, vars and related setting code.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Guo Ren <guoren@kernel.org>
Link: https://lore.kernel.org/r/20230128172856.3814-14-jszhang@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

Switch has_svinval() from static branch to the new helper
riscv_has_extension_unlikely().

Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Guo Ren <guoren@kernel.org>
Acked-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20230128172856.3814-13-jszhang@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

Switch cpu_relax() from static branch to the new helper
riscv_has_extension_likely()

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Guo Ren <guoren@kernel.org>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230128172856.3814-12-jszhang@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

Make it possible to use alternatives in the vDSO, so that better
implementations can be used if possible.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Reviewed-by: Guo Ren <guoren@kernel.org>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Link: https://lore.kernel.org/r/20230128172856.3814-11-jszhang@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>