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Merge branch 'bugfix/semihosting_vfs_asm' into 'master'

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xtensa: fix semihosting arguments potentially begin optimized out

See merge request espressif/esp-idf!16880
This commit is contained in:
Ivan Grokhotkov 2022-01-21 10:28:19 +00:00
commit e090b6b031
1 changed files with 21 additions and 17 deletions
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38
components/xtensa/include/xtensa/semihosting.h
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@ -27,28 +27,32 @@ extern "C" {
*/ */
static inline long semihosting_call(long id, long *data, int *out_errno) // NOLINT(readability-non-const-parameter) static inline long semihosting_call(long id, long *data, int *out_errno) // NOLINT(readability-non-const-parameter)
{ {
long host_ret; /* GCC doesn't allow using specific register names in constraints for Xtensa.
long host_errno; * For this case, GCC extended inline assembly manual says the following:
* If you must use a specific register, but your Machine Constraints do not provide
* sufficient control to select the specific register you want, local register variables
* may provide a solution.
* Using local register variables results in simpler generated code than
* the previous implementation which listed a2-a6 as clobbered registers.
*/
register long a2 asm ("a2") = id;
register long a3 asm ("a3") = (long) data[0];
register long a4 asm ("a4") = (long) data[1];
register long a5 asm ("a5") = (long) data[2];
register long a6 asm ("a6") = (long) data[3];
/* The break instruction operands should be (1, 14) according to the ISA manual. /* The break instruction operands should be (1, 14) according to the ISA manual.
* We keep (1, 1) for compatibility, until OpenOCD is updated to support both * We keep (1, 1) for compatibility, until OpenOCD is updated to support both
* conventions. * conventions.
*/ */
__asm__ __volatile__ ( __asm__ __volatile__ (
"mov a2, %[sys_nr]\n" \ "break 1, 1\n"
"mov a3, %[arg1]\n" \ : "+r"(a2), "+r"(a3)
"mov a4, %[arg2]\n" \ : "r"(a4), "r"(a5), "r"(a6)
"mov a5, %[arg3]\n" \ : "memory");
"mov a6, %[arg4]\n" \
"break 1, 1\n" \ long host_ret = a2;
"mov %[host_ret], a2\n" \ long host_errno = a3;
"mov %[host_errno], a3\n" \
:[host_ret]"=r"(host_ret), [host_errno]"=r"(host_errno)
:[sys_nr]"r"(id),
[arg1]"r"(data[0]),
[arg2]"r"(data[1]),
[arg3]"r"(data[2]),
[arg4]"r"(data[3])
:"a2", "a3", "a4", "a5", "a6");
if (host_ret < 0) { if (host_ret < 0) {
*out_errno = host_errno; *out_errno = host_errno;
} }