[PATCH v3 1/3] lib: Add common semihosting library

Kautuk Consul
2022-09-19T11:23:13Z

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 | 46 +++++++++
lib/Makefile | 2 +
lib/semihosting.c | 186 +++++++++++++++++++++++++++++++++++++
6 files changed, 246 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..97920e7552 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -71,6 +71,52 @@ config HAVE_PRIVATE_LIBGCC
config LIB_UUID
bool

+config SEMIHOSTING
+ bool "Support 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 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 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);
+}
--
2.34.1