Re: [PATCH v5 1/3] lib: Add common semihosting library

On 9/23/22 3:03 AM, Kautuk Consul wrote:

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

arch/arm/Kconfig | 46 --------- arch/arm/lib/semihosting.c | 181 +----------------------------------- include/semihosting.h | 11 +++ lib/Kconfig | 47 ++++++++++ lib/Makefile | 2 + lib/semihosting.c | 186 +++++++++++++++++++++++++++++++++++++ 6 files changed, 247 insertions(+), 226 deletions(-) create mode 100644 lib/semihosting.c

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 82cd456f51..ee6a9fadd9 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -413,52 +413,6 @@ config ARM_SMCCC This should be enabled if U-Boot needs to communicate with system firmware (for example, PSCI) according to SMCCC.

-config SEMIHOSTING

• bool "Support ARM semihosting"
• help

•  Semihosting is a method for a target to communicate with a host
  

•  debugger. It uses special instructions which the debugger will trap
  

•  on and interpret. This allows U-Boot to read/write files, print to
  

•  the console, and execute arbitrary commands on the host system.
  

•  Enabling this option will add support for reading and writing files
  

•  on the host system. If you don't have a debugger attached then trying
  

•  to do this will likely cause U-Boot to hang. Say 'n' if you are unsure.
  

-config SEMIHOSTING_FALLBACK

• bool "Recover gracefully when semihosting fails"
• depends on SEMIHOSTING && ARM64
• default y
• help

•  Normally, if U-Boot makes a semihosting call and no debugger is
  

•  attached, then it will panic due to a synchronous abort
  

•  exception. This config adds an exception handler which will allow
  

•  U-Boot to recover. Say 'y' if unsure.
  

-config SPL_SEMIHOSTING

• bool "Support ARM semihosting in SPL"
• depends on SPL
• help

•  Semihosting is a method for a target to communicate with a host
  

•  debugger. It uses special instructions which the debugger will trap
  

•  on and interpret. This allows U-Boot to read/write files, print to
  

•  the console, and execute arbitrary commands on the host system.
  

•  Enabling this option will add support for reading and writing files
  

•  on the host system. If you don't have a debugger attached then trying
  

•  to do this will likely cause U-Boot to hang. Say 'n' if you are unsure.
  

-config SPL_SEMIHOSTING_FALLBACK

• bool "Recover gracefully when semihosting fails in SPL"
• depends on SPL_SEMIHOSTING && ARM64
• select ARMV8_SPL_EXCEPTION_VECTORS
• default y
• help

•  Normally, if U-Boot makes a semihosting call and no debugger is
  

•  attached, then it will panic due to a synchronous abort
  

•  exception. This config adds an exception handler which will allow
  

•  U-Boot to recover. Say 'y' if unsure.
  

config SYS_THUMB_BUILD bool "Build U-Boot using the Thumb instruction set" depends on !ARM64 diff --git a/arch/arm/lib/semihosting.c b/arch/arm/lib/semihosting.c index 01d652a6b8..11e7b85ee6 100644 --- a/arch/arm/lib/semihosting.c +++ b/arch/arm/lib/semihosting.c @@ -10,25 +10,11 @@

• available in silicon now, fastmodel usage makes less sense for them.

*/ #include <common.h> -#include <log.h> -#include <semihosting.h>

-#define SYSOPEN 0x01 -#define SYSCLOSE 0x02 -#define SYSWRITEC 0x03 -#define SYSWRITE0 0x04 -#define SYSWRITE 0x05 -#define SYSREAD 0x06 -#define SYSREADC 0x07 -#define SYSISERROR 0x08 -#define SYSSEEK 0x0A -#define SYSFLEN 0x0C -#define SYSERRNO 0x13

/*

• Call the handler

*/ -static noinline long smh_trap(unsigned int sysnum, void *addr) +long smh_trap(unsigned int sysnum, void *addr) { register long result asm("r0"); #if defined(CONFIG_ARM64) @@ -41,168 +27,3 @@ static noinline long smh_trap(unsigned int sysnum, void *addr) #endif return result; }

-#if CONFIG_IS_ENABLED(SEMIHOSTING_FALLBACK) -static bool _semihosting_enabled = true; -static bool try_semihosting = true;

-bool semihosting_enabled(void) -{

• if (try_semihosting) {

• smh_trap(SYSERRNO, NULL);
  

• try_semihosting = false;
  

• }
• return _semihosting_enabled;

-}

-void disable_semihosting(void) -{

• _semihosting_enabled = false;

-} -#endif

-/**

• • smh_errno() - Read the host's errno
• • This gets the value of the host's errno and negates it. The host's errno may
• • or may not be set, so only call this function if a previous semihosting call
• • has failed.
• • Return: a negative error value
• */

-static int smh_errno(void) -{

• long ret = smh_trap(SYSERRNO, NULL);
• if (ret > 0 && ret < INT_MAX)

• return -ret;
  

• return -EIO;

-}

-long smh_open(const char *fname, enum smh_open_mode mode) -{

• long fd;
• struct smh_open_s {

• const char *fname;
  

• unsigned long mode;
  

• size_t len;
  

• } open;
• debug("%s: file '%s', mode '%u'\n", __func__, fname, mode);
• open.fname = fname;
• open.len = strlen(fname);
• open.mode = mode;
• /* Open the file on the host */
• fd = smh_trap(SYSOPEN, &open);
• if (fd == -1)

• return smh_errno();
  

• return fd;

-}

-/**

• • struct smg_rdwr_s - Arguments for read and write
• • @fd: A file descriptor returned from smh_open()
• • @memp: Pointer to a buffer of memory of at least @len bytes
• • @len: The number of bytes to read or write
• */

-struct smh_rdwr_s {

• long fd;
• void *memp;
• size_t len;

-};

-long smh_read(long fd, void *memp, size_t len) -{

• long ret;
• struct smh_rdwr_s read;
• debug("%s: fd %ld, memp %p, len %zu\n", __func__, fd, memp, len);
• read.fd = fd;
• read.memp = memp;
• read.len = len;
• ret = smh_trap(SYSREAD, &read);
• if (ret < 0)

• return smh_errno();
  

• return len - ret;

-}

-long smh_write(long fd, const void *memp, size_t len, ulong *written) -{

• long ret;
• struct smh_rdwr_s write;
• debug("%s: fd %ld, memp %p, len %zu\n", __func__, fd, memp, len);
• write.fd = fd;
• write.memp = (void *)memp;
• write.len = len;
• ret = smh_trap(SYSWRITE, &write);
• *written = len - ret;
• if (ret)

• return smh_errno();
  

• return 0;

-}

-long smh_close(long fd) -{

• long ret;
• debug("%s: fd %ld\n", __func__, fd);
• ret = smh_trap(SYSCLOSE, &fd);
• if (ret == -1)

• return smh_errno();
  

• return 0;

-}

-long smh_flen(long fd) -{

• long ret;
• debug("%s: fd %ld\n", __func__, fd);
• ret = smh_trap(SYSFLEN, &fd);
• if (ret == -1)

• return smh_errno();
  

• return ret;

-}

-long smh_seek(long fd, long pos) -{

• long ret;
• struct smh_seek_s {

• long fd;
  

• long pos;
  

• } seek;
• debug("%s: fd %ld pos %ld\n", __func__, fd, pos);
• seek.fd = fd;
• seek.pos = pos;
• ret = smh_trap(SYSSEEK, &seek);
• if (ret)

• return smh_errno();
  

• return 0;

-}

-int smh_getc(void) -{

• return smh_trap(SYSREADC, NULL);

-}

-void smh_putc(char ch) -{

• smh_trap(SYSWRITEC, &ch);

-}

-void smh_puts(const char *s) -{

• smh_trap(SYSWRITE0, (char *)s);

-} diff --git a/include/semihosting.h b/include/semihosting.h index f1f73464e4..4e844cbad8 100644 --- a/include/semihosting.h +++ b/include/semihosting.h @@ -17,6 +17,17 @@ #define SMH_T32_SVC 0xDFAB #define SMH_T32_HLT 0xBABC

+/**

• • smh_trap() - ARCH-specific semihosting call.
• • Semihosting library/driver can use this function to do the
• • actual semihosting calls.
• • Return: Error code defined by semihosting spec.
• */

+long smh_trap(unsigned int sysnum, void *addr);

#if CONFIG_IS_ENABLED(SEMIHOSTING_FALLBACK) /**

• semihosting_enabled() - Determine whether semihosting is supported

diff --git a/lib/Kconfig b/lib/Kconfig index 6121c80dc8..de7e797f11 100644 --- a/lib/Kconfig +++ b/lib/Kconfig @@ -71,6 +71,53 @@ config HAVE_PRIVATE_LIBGCC config LIB_UUID bool

+config SEMIHOSTING

• bool "Support semihosting"
• depends on ARM
• help

•  Semihosting is a method for a target to communicate with a host
  

•  debugger. It uses special instructions which the debugger will trap
  

•  on and interpret. This allows U-Boot to read/write files, print to
  

•  the console, and execute arbitrary commands on the host system.
  

•  Enabling this option will add support for reading and writing files
  

•  on the host system. If you don't have a debugger attached then trying
  

•  to do this will likely cause U-Boot to hang. Say 'n' if you are unsure.
  

+config SEMIHOSTING_FALLBACK

• bool "Recover gracefully when semihosting fails"
• depends on SEMIHOSTING && ARM64
• default y
• help

•  Normally, if U-Boot makes a semihosting call and no debugger is
  

•  attached, then it will panic due to a synchronous abort
  

•  exception. This config adds an exception handler which will allow
  

•  U-Boot to recover. Say 'y' if unsure.
  

+config SPL_SEMIHOSTING

• bool "Support semihosting in SPL"
• depends on SPL && ARM
• help

•  Semihosting is a method for a target to communicate with a host
  

•  debugger. It uses special instructions which the debugger will trap
  

•  on and interpret. This allows U-Boot to read/write files, print to
  

•  the console, and execute arbitrary commands on the host system.
  

•  Enabling this option will add support for reading and writing files
  

•  on the host system. If you don't have a debugger attached then trying
  

•  to do this will likely cause U-Boot to hang. Say 'n' if you are unsure.
  

+config SPL_SEMIHOSTING_FALLBACK

• bool "Recover gracefully when semihosting fails in SPL"
• depends on SPL_SEMIHOSTING && ARM64
• select ARMV8_SPL_EXCEPTION_VECTORS
• default y
• help

•  Normally, if U-Boot makes a semihosting call and no debugger is
  

•  attached, then it will panic due to a synchronous abort
  

•  exception. This config adds an exception handler which will allow
  

•  U-Boot to recover. Say 'y' if unsure.
  

config PRINTF bool default y diff --git a/lib/Makefile b/lib/Makefile index e3deb15287..134c4319cd 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -145,6 +145,8 @@ obj-y += date.o obj-y += rtc-lib.o obj-$(CONFIG_LIB_ELF) += elf.o

+obj-$(CONFIG_$(SPL_TPL_)SEMIHOSTING) += semihosting.o

# # Build a fast OID lookup registry from include/linux/oid_registry.h # diff --git a/lib/semihosting.c b/lib/semihosting.c new file mode 100644 index 0000000000..831774e356 --- /dev/null +++ b/lib/semihosting.c @@ -0,0 +1,186 @@ +// SPDX-License-Identifier: GPL-2.0+ +/*

• • Copyright (C) 2022 Sean Anderson sean.anderson@seco.com
• • Copyright 2014 Broadcom Corporation
• */

+#include <common.h> +#include <log.h> +#include <semihosting.h>

+#define SYSOPEN 0x01 +#define SYSCLOSE 0x02 +#define SYSWRITEC 0x03 +#define SYSWRITE0 0x04 +#define SYSWRITE 0x05 +#define SYSREAD 0x06 +#define SYSREADC 0x07 +#define SYSISERROR 0x08 +#define SYSSEEK 0x0A +#define SYSFLEN 0x0C +#define SYSERRNO 0x13

+#if CONFIG_IS_ENABLED(SEMIHOSTING_FALLBACK) +static bool _semihosting_enabled = true; +static bool try_semihosting = true;

+bool semihosting_enabled(void) +{

• if (try_semihosting) {

• smh_trap(SYSERRNO, NULL);
  

• try_semihosting = false;
  

• }
• return _semihosting_enabled;

+}

+void disable_semihosting(void) +{

• _semihosting_enabled = false;

+} +#endif

+/**

• • smh_errno() - Read the host's errno
• • This gets the value of the host's errno and negates it. The host's errno may
• • or may not be set, so only call this function if a previous semihosting call
• • has failed.
• • Return: a negative error value
• */

+static int smh_errno(void) +{

• long ret = smh_trap(SYSERRNO, NULL);
• if (ret > 0 && ret < INT_MAX)

• return -ret;
  

• return -EIO;

+}

+long smh_open(const char *fname, enum smh_open_mode mode) +{

• long fd;
• struct smh_open_s {

• const char *fname;
  

• unsigned long mode;
  

• size_t len;
  

• } open;
• debug("%s: file '%s', mode '%u'\n", __func__, fname, mode);
• open.fname = fname;
• open.len = strlen(fname);
• open.mode = mode;
• /* Open the file on the host */
• fd = smh_trap(SYSOPEN, &open);
• if (fd == -1)

• return smh_errno();
  

• return fd;

+}

+/**

• • struct smg_rdwr_s - Arguments for read and write
• • @fd: A file descriptor returned from smh_open()
• • @memp: Pointer to a buffer of memory of at least @len bytes
• • @len: The number of bytes to read or write
• */

+struct smh_rdwr_s {

• long fd;
• void *memp;
• size_t len;

+};

+long smh_read(long fd, void *memp, size_t len) +{

• long ret;
• struct smh_rdwr_s read;
• debug("%s: fd %ld, memp %p, len %zu\n", __func__, fd, memp, len);
• read.fd = fd;
• read.memp = memp;
• read.len = len;
• ret = smh_trap(SYSREAD, &read);
• if (ret < 0)

• return smh_errno();
  

• return len - ret;

+}

+long smh_write(long fd, const void *memp, size_t len, ulong *written) +{

• long ret;
• struct smh_rdwr_s write;
• debug("%s: fd %ld, memp %p, len %zu\n", __func__, fd, memp, len);
• write.fd = fd;
• write.memp = (void *)memp;
• write.len = len;
• ret = smh_trap(SYSWRITE, &write);
• *written = len - ret;
• if (ret)

• return smh_errno();
  

• return 0;

+}

+long smh_close(long fd) +{

• long ret;
• debug("%s: fd %ld\n", __func__, fd);
• ret = smh_trap(SYSCLOSE, &fd);
• if (ret == -1)

• return smh_errno();
  

• return 0;

+}

+long smh_flen(long fd) +{

• long ret;
• debug("%s: fd %ld\n", __func__, fd);
• ret = smh_trap(SYSFLEN, &fd);
• if (ret == -1)

• return smh_errno();
  

• return ret;

+}

+long smh_seek(long fd, long pos) +{

• long ret;
• struct smh_seek_s {

• long fd;
  

• long pos;
  

• } seek;
• debug("%s: fd %ld pos %ld\n", __func__, fd, pos);
• seek.fd = fd;
• seek.pos = pos;
• ret = smh_trap(SYSSEEK, &seek);
• if (ret)

• return smh_errno();
  

• return 0;

+}

+int smh_getc(void) +{

• return smh_trap(SYSREADC, NULL);

+}

+void smh_putc(char ch) +{

• smh_trap(SYSWRITEC, &ch);

+}

+void smh_puts(const char *s) +{

• smh_trap(SYSWRITE0, (char *)s);

+}

Reviewed-by: Sean Anderson sean.anderson@seco.com