There is no functional change here, only improvement in code readability
by adding comments to explain where the kasan constants come from and by
replacing hardcoded numerical constant by the corresponding define.

Note that the comments come from arm64.
Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

At early boot stage, we have a whole PGDIR to map the kernel, so there
is no need to restrict the early mapping size to 128MB. Removing this
define also allows us to simplify some compile time logic.

This fixes large kernel mappings with a size greater than 128MB, as it
is the case for syzbot kernels whose size was just ~130MB.

Note that on rv64, for now, we are then limited to PGDIR size for early
mapping as we can't use PGD mappings (see [1]). That should be enough
given the relative small size of syzbot kernels compared to PGDIR_SIZE
which is 1GB.

[1] https://lore.kernel.org/lkml/20200603153608.30056-1-alex@ghiti.fr/Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
Tested-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

The rest of these are alphabetically sorted, and leaving it this way
causes a merge conflict.
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

We use the generic C VDSO implementations of a handful of clock-related
functions.  When kasan is enabled this results in asan stub calls that
are unlikely to be resolved by userspace, this just disables KASAN
when building the VDSO.

Verified the fix on a kernel with KASAN enabled using vDSO selftests.

Link: https://lore.kernel.org/lkml/CACT4Y+ZNJBnkKHXUf=tm_yuowvZvHwN=0rmJ=7J+xFd+9r_6pQ@mail.gmail.com/Tested-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Tested-by: Dmitry Vyukov <dvyukov@google.com>
[Palmer: commit text]
Fixes: ad5d1122 ("riscv: use vDSO common flow to reduce the latency of the time-related functions")
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

max_low_pfn and min_low_pfn are declared in linux/memblock.h,
and it also is included in arch/riscv/mm/init.c, drop unnecessary
declaration.
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

The nommu_k210_defconfig default configuration allows booting a Canaan
Kendryte K210 SoC based boards using an embedded intramfs cpio file.
Modifying this configuration to enable support for the board SD card is
not trivial for all users. To help beginners getting started with these
boards, add the nommu_k210_sdcard_defconfig default configuration file
to set all configuration options necessary to use the board mmc-spi sd
card for the root file system.

This new configuration adds support for the block layer, the mmc-spi
driver and modifies the boot options to specify the rootfs device as
mmcblk0p1 (first partition of the sd card block device). The ext2 file
system is selected by default to encourage its use as that results in
only about 4KB added to the kernel image size. As ext2 does not have
journaling, the boot options specify a read-only mount of the file
system. Similarly to the smaller nommu_k210_defconfig, this new default
configuration disables virtual terminal support to reduce the kernel
image size.

The default device tree selected is unchanged, specifying the simple
"k210_generic" device tree file. The user must change this setting to
specify the device tree suitable for the board being used
(sipeed_maix_bit, sipeed_maix_dock, sipeed_maix_go, sipeed_maixduino or
canaan_kd233).
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Update the Kendryte k210 nommu default configuration file
(nommu_k210_defconfig) to include device drivers for reset, reboot,
I2C, SPI, gpio and LEDs support. Virtual Terminal support is also
disabled as no terminal devices are supported and enabled. Disabling
CONFIG_VT (removing the no longer needed override for
CONFIG_VGA_CONSOLE) reduces the kernel image size by about 65 KB.

This default configuration remains suitable for a system using an
initramfs cpio file linked into the kernel image.
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Add the device tree canaan_kd233.dts for the Canaan Kendryte KD233
development board.  This device tree enables LEDs, some gpios and
spi/mmc SD card device. The WS2812B RGB LED and the 10 positions rotary
dip switch present on the board are left undefined.
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
[Palmer: Remove undocumented microphone entry, along with the use.]
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Add the device tree sipeed_maixduino.dts for the SiPeed MAIXDUINO board.
This device tree enables LEDs and spi/mmc SD card device. Additionally,
gpios and i2c are also enabled and mapped to the board header pins as
indicated on the board itself.
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
[Palmer: Remove undocumented microphone entry, along with the use.]
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Add the device tree sipeed_maix_go.dts for the SiPeed MAIX GO board.
This device tree enables buttons, LEDs, gpio, i2c and spi/mmc SD card
devices.
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
[Palmer: Remove undocumented microphone entry, along with the use.]
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Add the device tree sipeed_maix_dock.dts for the SiPeed MAIX DOCK m1
and m1w boards. This device tree enables LEDs, gpio, i2c and spi/mmc
SD card devices.
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
[Palmer: Remove undocumented microphone entry, along with the use.]
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Add the device tree sipeed_maix_bit.dts for the SiPeed MAIX BiT and
MAIX BiTm boards. This device tree enables LEDs, gpio, i2c and spi/mmc
SD card devices.
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
[Palmer: Remove undocumented microphone entry, along with the use.]
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Update the Canaan Kendryte K210 base device tree k210.dtsi to define
all supported peripherals of the SoC, their clocks and reset lines.
The device tree file k210.dts is renamed to k210_generic.dts and
becomes the default value selection of the configuration option
SOC_CANAAN_K210_DTB_BUILTIN_SOURCE. No device beside the serial console
is defined by this device tree. This makes this generic device tree
suitable for use with a builtin initramfs with all known K210 based
boards.

These changes result in the K210_CLK_ACLK clock ID to be unused and
removed from the dt-bindings k210-clk.h header file.

Most updates to the k210.dtsi file come from Sean Anderson's work on
U-Boot support for the K210.

Cc: Rob Herring <robh@kernel.org>
Cc: devicetree@vger.kernel.org
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

The Synopsis DesignWare APB timer driver
(drivers/clocksource/dw_apb_timer_of.c) indirectly uses the resets
property of its node as it executes the function of_reset_control_get().
Make sure that this property is documented in
timer/snps,dw-apb-timer.yaml to avoid make dtbs_check warnings.
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

The sifive gpio IP block supports up to 32 GPIOs. Reflect that in the
interrupts property description and maxItems. Also add the standard
ngpios property to describe the number of GPIOs available on the
implementation.

Also add the "canaan,k210-gpiohs" compatible string to indicate the use
of this gpio controller in the Canaan Kendryte K210 SoC. If this
compatible string is used, do not define the clocks property as
required as the K210 SoC does not have a software controllable clock
for the Sifive gpio IP block.
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Add the compatible string "canaan,k210-uarths" to the sifive uart
bindings to indicate the use of this IP block in the Canaan Kendryte
K210 SoC.
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Add the "canaan,k210-clint" compatible string to the Sifive clint
bindings to indicate the use of the "sifive,clint0" IP block in the
Canaan Kendryte K210 SoC. The description of the compatible string
property is also updated to reflect this addition.
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Add the compatible string "canaan,k210-plic" to the Sifive plic bindings
to indicate the use of the "sifive,plic-1.0.0" IP block in the Canaan
Kendryte K210 SoC. The description is also updated to reflect this
change, that is, that SoCs from other vendors may also use this plic
implementation.
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

The Canaan Kendryte K210 SoC CPU cores are based on a rocket chip
version using a draft verion of the RISC-V ISA specifications. To avoid
any confusion with CPU cores using stable specifications, add the
compatible string "canaan,k210" for this SoC CPU cores.

Also add the "riscv,none" value to the mmu-type property to allow a DT
to indicate that the CPU being described does not have an MMU or that
it has an MMU that is not usable (which is the case for the K210 SoC).
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Introduce the file riscv/canaan.yaml to document compatible strings
related to the Canaan Kendryte K210 SoC. The compatible string
"canaan,kendryte-k210" used to indicate the use of this SoC to the
early SoC init code is added. This new file also defines the compatible
strings of all supported boards based on this SoC.
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Add a reference to the Canaan K210 system controller driver bindings
file Documentation/devicetree/bindings/mfd/canaan,k210-sysctl.yaml
in the MAINTAINERS file entry for this driver.
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Add a clock provider driver for the Canaan Kendryte K210 RISC-V SoC.
This new driver with the compatible string "canaan,k210-clk" implements
support for the full clock structure of the K210 SoC. Since it is
required for the correct operation of the SoC, this driver is
selected by default for compilation when the SOC_CANAAN option is
selected.

With this change, the k210-sysctl driver is turned into a simple
platform driver which enables its power bus clock and triggers
populating its child nodes. The sysctl driver retains the SOC early
initialization code, but the implementation now relies on the new
function k210_clk_early_init() provided by the new clk-k210 driver.

The clock structure implemented and many of the coding ideas for the
driver come from the work by Sean Anderson on the K210 support for the
U-Boot project.

Cc: Stephen Boyd <sboyd@kernel.org>
Cc: Michael Turquette <mturquette@baylibre.com>
Cc: linux-clk@vger.kernel.org
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

SBI v0.2 functions can return an error code from SBI implementation.
We are already processing the SBI error code and coverts it to the Linux
error code.

Propagate to the error code to the caller as well. As of now, kvm is the
only user of these error codes.
Signed-off-by: Atish Patra <atish.patra@wdc.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Currently, we do local TLB flush on every MM switch. This is very harsh on
performance because we are forcing page table walks after every MM switch.

This patch implements ASID allocator for assigning an ASID to a MM context.
The number of ASIDs are limited in HW so we create a logical entity named
CONTEXTID for assigning to MM context. The lower bits of CONTEXTID are ASID
and upper bits are VERSION number. The number of usable ASID bits supported
by HW are detected at boot-time by writing 1s to ASID bits in SATP CSR.

We allocate new CONTEXTID on first MM switch for a MM context where the
ASID is allocated from an ASID bitmap and VERSION is provide by an atomic
counter. At time of allocating new CONTEXTID, if we run out of available
ASIDs then:
1. We flush the ASID bitmap
2. Increment current VERSION atomic counter
3. Re-allocate ASID from ASID bitmap
4. Flush TLB on all CPUs
5. Try CONTEXTID re-assignment on all CPUs

Please note that we don't use ASID #0 because it is used at boot-time by
all CPUs for initial MM context. Also, newly created context is always
assigned CONTEXTID #0 (i.e. VERSION #0 and ASID #0) which is an invalid
context in our implementation.

Using above approach, we have virtually infinite CONTEXTIDs on-top-of
limited number of HW ASIDs. This approach is inspired from ASID allocator
used for Linux ARM/ARM64 but we have adapted it for RISC-V. Overall, this
ASID allocator helps us reduce rate of local TLB flushes on every CPU
thereby increasing performance.

This patch is tested on QEMU virt machine, Spike and SiFive Unleashed
board. On QEMU virt machine, we see some (3-5% approx) performance
improvement with SW emulated TLBs provided by QEMU. Unfortunately,
the ASID bits of the SATP CSR are not implemented on Spike and SiFive
Unleashed board so we don't see any change in performance. On real HW
having all ASID bits implemented, the performance gains will be much
more due improved sharing of TLB among different processes.
Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Fix build warnings in the arch_numa common code:

../include/linux/kern_levels.h:5:18: warning: format '%Lx' expects argument of type 'long long unsigned int', but argument 3 has type 'phys_addr_t' {aka 'unsigned int'} [-Wformat=]
../drivers/base/arch_numa.c:360:56: note: format string is defined here
  360 |    pr_warn("Warning: invalid memblk node %d [mem %#010Lx-%#010Lx]\n",
../drivers/base/arch_numa.c:435:39: note: format string is defined here
  435 |  pr_info("Faking a node at [mem %#018Lx-%#018Lx]\n", start, end - 1);

Fixes: ae3c107c ("numa: Move numa implementation to common code")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reported-by: kernel test robot <lkp@intel.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Remove a superfluous semicolon after function definition.
Signed-off-by: Chengyang Fan <cy.fan@huawei.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Neither of these are actually correct: the instruction stream is defined
(for versions of the ISA manual newer than 2.2) as a stream of 16-bit
little-endian parcels, which is different than just being little-endian.
In theory we should represent this as a type, but we don't have any
concrete plans for the big endian stuff so it doesn't seem worth the
time -- we've got variants of this all over the place.

Instead I'm just dropping the unnecessary type conversion, which is a
NOP on LE systems but causes an sparse error as the types are all mixed
up.
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
Acked-by: Guo Ren <guoren@kernel.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Add the pinctrl-k210.c pinctrl driver for the Canaan Kendryte K210
field programmable IO array (FPIOA) to allow configuring the SoC pin
functions. The K210 has 48 programmable pins which can take any of 256
possible functions.

This patch is inspired from the k210 pinctrl driver for the u-boot
project and contains many direct contributions from Sean Anderson.

The MAINTAINERS file is updated, adding the entry "CANAAN/KENDRYTE K210
SOC FPIOA DRIVER" with myself listed as maintainer for this driver.

Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: linux-gpio@vger.kernel.org
Signed-off-by: Sean Anderson <seanga2@gmail.com>
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

"kerne" -> "kernel"
Signed-off-by: WenZhang <zhangwen@yulong.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

It references to x86/s390 architecture.

So, it doesn't map the early shadow page to cover VMALLOC space.

Prepopulate top level page table for the range that would otherwise be
empty.

lower levels are filled dynamically upon memory allocation while
booting.
Signed-off-by: Nylon Chen <nylon7@andestech.com>
Signed-off-by: Nick Hu <nickhu@andestech.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Covert to the generic reserve_initrd_mem() function.
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Some architectures(eg, ARM and riscv) have similar logic to
check and reserve the memory of initrd, let's provide a common
function reserve_initrd_mem() to reduce duplicated code.
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Add the preprocessor guard in initrd.h to prevent possible
build error from the multiple inclusion of same header file
multiple time.
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Sometimes, especially in a production system we may not want to
use a "smart bootloader" like u-boot to load kernel, ramdisk and
device tree from a filesystem on eMMC, but rather load the kernel
from a NAND partition and just run it as soon as we can, and in
this case it is convenient to have device tree compiled into the
kernel binary. Since this case is not limited to MMU-less systems,
let's support it for these which have MMU enabled too.

While at it, provide __dtb_start as a parameter to setup_vm() in
BUILTIN_DTB case, so we don't have to duplicate BUILTIN_DTB specific
processing in MMU-enabled and MMU-disabled versions of setup_vm().
Signed-off-by: Vitaly Wool <vitaly.wool@konsulko.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

When a function doesn't have a callee, then it will not
push ra into the stack, such as lkdtm_BUG() function,

addi	sp,sp,-16
sd	s0,8(sp)
addi	s0,sp,16
ebreak

The struct stackframe use {fp,ra} to get information from
stack, if walk_stackframe() with pr_regs, we will obtain
wrong value and bad stacktrace,

[<ffffffe00066c56c>] lkdtm_BUG+0x6/0x8
---[ end trace 18da3fbdf08e25d5 ]---

Correct the next fp and pc, after that, full stacktrace
shown as expects,

[<ffffffe00066c56c>] lkdtm_BUG+0x6/0x8
[<ffffffe0008b24a4>] lkdtm_do_action+0x14/0x1c
[<ffffffe00066c372>] direct_entry+0xc0/0x10a
[<ffffffe000439f86>] full_proxy_write+0x42/0x6a
[<ffffffe000309626>] vfs_write+0x7e/0x214
[<ffffffe00030992a>] ksys_write+0x98/0xc0
[<ffffffe000309960>] sys_write+0xe/0x16
[<ffffffe0002014bc>] ret_from_syscall+0x0/0x2
---[ end trace 61917f3d9a9fadcd ]---
Signed-off-by: Chen Huang <chenhuang5@huawei.com>
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Show the function symbols of epc and ra to improve the
readability of crash reports, and align the printing
formats about the raw epc value.
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Like commit 1149aad1 ("arm64: Add dump_backtrace() in show_regs"),
dump the stack in riscv show_regs as common code expects.
Reviewed-by: Atish Patra <atish.patra@wdc.com>
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

This enables the use of per-task stack canary values if GCC has
support for emitting the stack canary reference relative to the
value of tp, which holds the task struct pointer in the riscv
kernel.

After compare arm64 and x86 implementations, seems arm64's is more
flexible and readable. The key point is how gcc get the offset of
stack_canary from gs/el0_sp.

x86: Use a fix offset from gs, not flexible.

struct fixed_percpu_data {
	/*
	 * GCC hardcodes the stack canary as %gs:40.  Since the
	 * irq_stack is the object at %gs:0, we reserve the bottom
	 * 48 bytes of the irq stack for the canary.
	 */
	char            gs_base[40]; // :(
	unsigned long   stack_canary;
};

arm64: Use -mstack-protector-guard-offset & guard-reg
	gcc options:
	-mstack-protector-guard=sysreg
	-mstack-protector-guard-reg=sp_el0
	-mstack-protector-guard-offset=xxx

riscv: Use -mstack-protector-guard-offset & guard-reg
	gcc options:
	-mstack-protector-guard=tls
	-mstack-protector-guard-reg=tp
	-mstack-protector-guard-offset=xxx

 GCC's implementation has been merged:
 commit c931e8d5a96463427040b0d11f9c4352ac22b2b0
 Author: Cooper Qu <cooper.qu@linux.alibaba.com>
 Date:   Mon Jul 13 16:15:08 2020 +0800

     RISC-V: Add support for TLS stack protector canary access

In the end, these codes are inserted by gcc before return:

*  0xffffffe00020b396 <+120>:   ld      a5,1008(tp) # 0x3f0
*  0xffffffe00020b39a <+124>:   xor     a5,a5,a4
*  0xffffffe00020b39c <+126>:   mv      a0,s5
*  0xffffffe00020b39e <+128>:   bnez    a5,0xffffffe00020b61c <_do_fork+766>
   0xffffffe00020b3a2 <+132>:   ld      ra,136(sp)
   0xffffffe00020b3a4 <+134>:   ld      s0,128(sp)
   0xffffffe00020b3a6 <+136>:   ld      s1,120(sp)
   0xffffffe00020b3a8 <+138>:   ld      s2,112(sp)
   0xffffffe00020b3aa <+140>:   ld      s3,104(sp)
   0xffffffe00020b3ac <+142>:   ld      s4,96(sp)
   0xffffffe00020b3ae <+144>:   ld      s5,88(sp)
   0xffffffe00020b3b0 <+146>:   ld      s6,80(sp)
   0xffffffe00020b3b2 <+148>:   ld      s7,72(sp)
   0xffffffe00020b3b4 <+150>:   addi    sp,sp,144
   0xffffffe00020b3b6 <+152>:   ret
   ...
*  0xffffffe00020b61c <+766>:   auipc   ra,0x7f8
*  0xffffffe00020b620 <+770>:   jalr    -1764(ra) # 0xffffffe000a02f38 <__stack_chk_fail>
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Cooper Qu <cooper.qu@linux.alibaba.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Inspired by the commit 42d038c4 ("arm64: Add support for function
error injection"), this patch supports function error injection for
riscv.

This patch mainly support two functions: one is regs_set_return_value()
which is used to overwrite the return value; the another function is
override_function_with_return() which is to override the probed
function returning and jump to its caller.

Test log:
 cd /sys/kernel/debug/fail_function
 echo sys_clone > inject
 echo 100 > probability
 echo 1 > interval
 ls /
[  313.176875] FAULT_INJECTION: forcing a failure.
[  313.176875] name fail_function, interval 1, probability 100, space 0, times 1
[  313.184357] CPU: 0 PID: 87 Comm: sh Not tainted 5.8.0-rc5-00007-g6a758cc #117
[  313.187616] Call Trace:
[  313.189100] [<ffffffe0002036b6>] walk_stackframe+0x0/0xc2
[  313.191626] [<ffffffe00020395c>] show_stack+0x40/0x4c
[  313.193927] [<ffffffe000556c60>] dump_stack+0x7c/0x96
[  313.194795] [<ffffffe0005522e8>] should_fail+0x140/0x142
[  313.195923] [<ffffffe000299ffc>] fei_kprobe_handler+0x2c/0x5a
[  313.197687] [<ffffffe0009e2ec4>] kprobe_breakpoint_handler+0xb4/0x18a
[  313.200054] [<ffffffe00020357e>] do_trap_break+0x36/0xca
[  313.202147] [<ffffffe000201bca>] ret_from_exception+0x0/0xc
[  313.204556] [<ffffffe000201bbc>] ret_from_syscall+0x0/0x2
-sh: can't fork: Invalid argument
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Palmer Dabbelt <palmerdabbelt@google.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

This patch adds support for uprobes on riscv architecture.

Just like kprobe, it support single-step and simulate instructions.
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Palmer Dabbelt <palmerdabbelt@google.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>