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So far we used inline assembly to inject the actual instruction that
triggers the semihosting service. While this sounds elegant, as it's
really only about one instruction, it has some serious downsides:
- We need some barriers in place to force the compiler to issue writes
to a data structure before issuing the trap instruction.
- We need to convince the compiler to actually fill the structures that
we use pointers to.
- We need a memory clobber to avoid the compiler caching the data in
those structures, when semihosting writes data back.
- We need register arguments to make sure the function ID and the
pointer land in the right registers.
This is all doable, but fragile and somewhat cumbersome. Since we now
have a separate function in an extra file anyway, we can do away with
all the magic and just write that in an actual assembly file.
This is much more readable and robust.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Sean Anderson <sean.anderson@seco.com>
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We factor out the arch-independent parts of the ARM semihosting
implementation as a common library so that it can be shared
with RISC-V.
Signed-off-by: Kautuk Consul <kconsul@ventanamicro.com>
Reviewed-by: Leo Yu-Chi Liang <ycliang@andestech.com>
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Currently our semihosting trap function is somewhat fragile: we rely
on the current compiler behaviour to assign the second inline assembly
argument to the next free register (r1/x1), which happens to be the
"addr" argument to the smh_trap() function (per the calling convention).
I guess this is also the reason for the noinline attribute.
Make it explicit what we want: the "addr" argument needs to go into r1,
so we add another register variable. This allows to drop the "noinline"
attribute, so now the compiler beautifully inlines just the trap
instruction directly into the calling function.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
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Commit f4b540e25c5c("arm: smh: Fix uninitialized parameters with newer
GCCs") added a memory clobber to the semihosting inline assembly trap
calls, to avoid too eager GCC optimisation: when passing a pointer, newer
compilers couldn't be bothered to actually fill in the structure that it
pointed to, as this data would seemingly never be used (at least from the
compiler's point of view).
But instead of the memory clobber we need to tell the compiler that we are
passing an *array* instead of some generic pointer, this forces the
compiler to actually populate the data structure.
This involves some rather hideous cast, which is best hidden in a macro.
But regardless of that, we actually need the memory clobber, but for two
different reasons: explain them in comments.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
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The ARM semihosting interface uses different trap instructions for
different architectures and instruction sets. So far we were using
AArch64 and ARMv7-M, and had an untested v7-A entry. The latter does
not work when building for Thumb, as can be verified by using
qemu_arm_defconfig, then enabling SEMIHOSTING and SYS_THUMB_BUILD:
==========
{standard input}:35: Error: invalid swi expression
{standard input}:35: Error: value of 1193046 too large for field of 2 bytes at 0
==========
Fix this by providing the recommended instruction[1] for Thumb, and
using the ARM instruction only when not building for Thumb. This also
removes some comment, as QEMU for ARM allows to now test this case.
Also use the opportunity to clean up the inline assembly, and just define
the actual trap instruction inside #ifdef's, to improve readability.
[1] https://developer.arm.com/documentation/dui0471/g/Semihosting/The-semihosting-interface?lang=en
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
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Newer versions of GCC won't initialize parts of structures which don't
appear to be used. This results in uninitialized semihosting parameters
passed via R1. Fix this by marking the inline assembly as clobbering
memory.
Signed-off-by: Sean Anderson <sean.anderson@seco.com>
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These functions are intended to support detecting semihosting and
falling back gracefully to alternative implementations. The test starts
by making semihosting call. SYS_ERRNO is chosen because it should not
mutate any state. If this semihosting call results in an exception
(rather than being caught by the debugger), then the exception handler
should call disable_semihosting() and resume execution after the call.
Ideally, this would just be part of semihosting by default, and not a
separate config. However, to reduce space ARM SPL doesn't include
exception vectors by default. This means we can't detect if a
semihosting call failed unless we enable them. To avoid forcing them to
be enabled, we use a separate config option. It might also be possible
to try and detect whether a debugger has enabled (by reading HDE from
DSCR), but I wasn't able to figure out a way to do this from all ELs.
This patch just introduces the generic code to handle detection. The
next patch will implement it for arm64 (but not arm32).
Signed-off-by: Sean Anderson <sean.anderson@seco.com>
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This adds three wrappers around the semihosting commands for reading and
writing to the host console. We use the more standard getc/putc/puts
names instead of readc/writec/write0 for familiarity.
Signed-off-by: Sean Anderson <sean.anderson@seco.com>
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This command's functionality is now completely implemented by the
standard fs load command. Convert the vexpress64 boot command (which is
the only user) and remove the implementation.
Signed-off-by: Sean Anderson <sean.anderson@seco.com>
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Most U-Boot command deal with start/size instead of start/end. Convert
the "fdt chosen" command to use these semantics as well. The only user
of this subcommand is vexpress, so convert the smhload command to use
this as well. We don't bother renaming the variable in vexpress64's
bootcommand, since it will be rewritten in the next commit.
Signed-off-by: Sean Anderson <sean.anderson@seco.com>
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In order to add filesystem support, we will need to be able to seek and
write files. Add the appropriate helper functions.
Signed-off-by: Sean Anderson <sean.anderson@seco.com>
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This adds some documentation for semihosting functions in the header.
Signed-off-by: Sean Anderson <sean.anderson@seco.com>
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Instead of printing in what are now library functions, try to return a
numeric error code. This also adjust some functions (such as read) to
behave more similarly to read(2). For example, we now return the number
of bytes read instead of failing immediately on a short read.
Signed-off-by: Sean Anderson <sean.anderson@seco.com>
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There's no point in using string constants for smh_open if we are just
going to have to parse them. Instead, use numeric modes. The user needs
to be a bit careful with these, since they are much closer semantically
to string modes used by fopen(3) than the numeric modes used with
open(2).
Signed-off-by: Sean Anderson <sean.anderson@seco.com>
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This exports semihosting functions for use in other files. The header is
in include/ and not arm/include/asm because I anticipate that RISC-V may
want to add their own implementation at some point.
smh_len_fd has been renamed to smh_flen to more closely match the
semihosting spec.
Signed-off-by: Sean Anderson <sean.anderson@seco.com>
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It is a pain to have to specify the value 16 in each call. Add a new
hextoul() function and update the code to use it.
Add a proper comment to simple_strtoul() while we are here.
Signed-off-by: Simon Glass <sjg@chromium.org>
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Move this header out of the common header.
Signed-off-by: Simon Glass <sjg@chromium.org>
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We should not use typedefs in U-Boot. They cannot be used as forward
declarations which means that header files must include the full header to
access them.
Drop the typedef and rename the struct to remove the _s suffix which is
now not useful.
This requires quite a few header-file additions.
Signed-off-by: Simon Glass <sjg@chromium.org>
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When U-Boot started using SPDX tags we were among the early adopters and
there weren't a lot of other examples to borrow from. So we picked the
area of the file that usually had a full license text and replaced it
with an appropriate SPDX-License-Identifier: entry. Since then, the
Linux Kernel has adopted SPDX tags and they place it as the very first
line in a file (except where shebangs are used, then it's second line)
and with slightly different comment styles than us.
In part due to community overlap, in part due to better tag visibility
and in part for other minor reasons, switch over to that style.
This commit changes all instances where we have a single declared
license in the tag as both the before and after are identical in tag
contents. There's also a few places where I found we did not have a tag
and have introduced one.
Signed-off-by: Tom Rini <trini@konsulko.com>
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We are now using an env_ prefix for environment functions. Rename setenv()
for consistency. Also add function comments in common.h.
Suggested-by: Wolfgang Denk <wd@denx.de>
Signed-off-by: Simon Glass <sjg@chromium.org>
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do_smhload was using a ulong to store the return value from
smh_load_file. That returns an int, where -1 indicates an error. As a
ulong will never be negative, smh_load_file errors were not detected and
so_smhload always returned zero.
Also, when errors were spotted, do_smhload was returning 1, rather than
the enumeration CMD_RET_FAILURE (which is also 1).
Signed-off-by: Ryan Harkin <ryan.harkin@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
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This patch fixes compile warnings like this:
warning: format '%lu' expects argument of type 'long unsigned int',
but argument 5 has type 'size_t'
In C99 standard you can use %zu modifier to print size_t values.
Signed-off-by: Vadzim Dambrouski <pftbest@gmail.com>
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If you enable CONFIG_SEMIHOSTING for STM32F429 target, you will get compile
error looking like this:
arch/arm/lib/semihosting.c: In function 'smh_read':
{standard input}: Assembler messages:
{standard input}:34: Error: invalid swi expression
{standard input}:34: Error: value of 1193046 too large for field of 2 bytes at 0
scripts/Makefile.build:277: recipe for target 'arch/arm/lib/semihosting.o' failed
The source of the problem is "svc #0x123456" instruction. This instruction
can not be encoded using Thumb2 instruction set used by ARMv7M CPUs.
ARM documentation suggests using "bkpt #0xAB" instruction instead [1].
This patch fixes compile errors and adds support for semihosting for
STM32F429 or any other ARMv7M target.
This change was sested on STM32F429-DISCOVERY board using OpenOCD and
"smhload" u-boot command.
[1] http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0471c/Bgbjhiea.html
Signed-off-by: Vadzim Dambrouski <pftbest@gmail.com>
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Now that loading files using semihosting can be done using
a command in standard scripts, and we have rewritten the boardfile
and added it to the Vexpress64, let's delete the external
interface to the semihosting file retrieveal and rely solely
on these commands, and staticize them inside that file so the
whole business is self-contained.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
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Instead of sprinkling custom code and calls over the Vexpress64
boardfile, create a command that loads images using semihosting
just like we would load from flash memory of over the network,
using a special command:
smhload <image> <address>
This will make it possible to remove some custom calls and
code and make the boot easier.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
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The semihosting trap call does not like being inlined, probably
because that will mean register reordering screwing up the return
value in r0, so tag this function "noinline".
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
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By rearranging the functions in the semihosting code we can
avoid forward-declaration of the internal static functions.
This puts the stuff in a logical order: read/open/close/len
and then higher-order functions follow at the end.
Cc: Darwin Rambo <drambo@broadcom.com>
Cc: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Mark Hambleton <mark.hambleton@arm.com>
Cc: Tom Rini <trini@ti.com>
Acked-by: Steve Rae <srae@broadcom.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
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There is currently a regression when using newer ARM64 compilers
for semihosting: the way long types are inferred from context
is no longer the same.
The semihosting runtime uses long and size_t, so use this
explicitly in the semihosting code and interface, and voila:
the code now works again.
Tested with aarch64-linux-gnu-gcc: Linaro GCC 4.9-2014.09.
Cc: Darwin Rambo <drambo@broadcom.com>
Cc: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Mark Hambleton <mark.hambleton@arm.com>
Cc: Tom Rini <trini@ti.com>
Acked-by: Steve Rae <srae@broadcom.com>
Suggested-by: Mark Hambleton <mark.hambleton@arm.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
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The semihosting code exposes internal file handle handling
functions to read(), open(), close() and get the length of
a certain file handle.
However the code using it is only interested in either
reading and entire named file into memory or getting the
file length of a file referred by name. No file handles
are used.
Thus make the file handle code internal to this file by
removing these functions from the semihosting header file
and staticize them.
This gives us some freedom to rearrange the semihosting
code without affecting the external interface.
Cc: Darwin Rambo <drambo@broadcom.com>
Cc: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Mark Hambleton <mark.hambleton@arm.com>
Cc: Tom Rini <trini@ti.com>
Acked-by: Steve Rae <srae@broadcom.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
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The armv8 ARM Trusted Firmware (ATF) can be used to load various ATF
images and u-boot, and does this for virtual platforms by using
semihosting. This commit extends this idea by allowing u-boot to also
use semihosting to load the kernel/ramdisk/dtb. This eliminates the need
for a bootwrapper and produces a more realistic boot sequence with
virtual models.
Though the semihosting code is quite generic, support for armv7 in
fastmodel is less useful due to the wide range of available silicon
and the lack of a free armv7 fastmodel, so this change contains an
untested armv7 placeholder for the service trap opcode.
Please refer to doc/README.semihosting for a more detailed description
of semihosting and how it is used with the armv8 virtual platforms.
Signed-off-by: Darwin Rambo <drambo@broadcom.com>
Cc: trini@ti.com
Cc: fenghua@phytium.com.cn
Cc: bhupesh.sharma@freescale.com
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