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esp32s3: improve exception handlers, add procPin/procUnpin, and linker wrap flags

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Rewrite kernel and double exception handlers to save EXCCAUSE/EPC1 to
RTC STORE registers before triggering a software reset, replacing the
LED-blink diagnostic with post-mortem debug info that survives reset.

Add user exception dispatch in the level-1 handler with a weak
espradio_user_exception symbol so programs without espradio still link.

Implement procPin/procUnpin for Xtensa using RSIL/WSR PS to properly
disable interrupts during atomic operations. Fix abort() to use a
waiti loop instead of bare spin.

Add --wrap ldflags for malloc/calloc/free/realloc/ppCheckTxConnTrafficIdle
to support espradio WiFi blob integration.

Signed-off-by: deadprogram <ron@hybridgroup.com>
This commit is contained in:
deadprogram
2026-04-07 12:15:39 +02:00
committed by Ron Evans
parent c3d514a751
commit a24dc8c543
4 changed files with 126 additions and 29 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/runtime/arch_xtensa.go
+20
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@@ -2,6 +2,8 @@
package runtime
import "device"
const GOARCH = "arm" // xtensa pretends to be arm
// The bitness of the CPU (e.g. 8, 32, 64).
@@ -19,3 +21,21 @@ func align(ptr uintptr) uintptr {
func getCurrentStackPointer() uintptr {
return uintptr(stacksave())
}
// Disable interrupts for procPin/procUnpin using the Xtensa RSIL/WSR PS
// instructions. A global variable is safe here because accesses happen
// with interrupts disabled.
var procPinnedMask uintptr
//go:linkname procPin sync/atomic.runtime_procPin
func procPin() {
// rsil sets PS.INTLEVEL=15 (mask all) and returns the old PS.
procPinnedMask = uintptr(device.AsmFull("rsil {}, 15", nil))
}
//go:linkname procUnpin sync/atomic.runtime_procUnpin
func procUnpin() {
device.AsmFull("wsr {state}, PS", map[string]interface{}{
"state": procPinnedMask,
})
}
src/runtime/runtime_esp32s3.go
+4 -1
View File
@@ -96,8 +96,11 @@ func init() {
}
func abort() {
// lock up forever
print("abort called\n")
// lock up forever
for {
device.Asm("waiti 0")
}
}
// interruptInit installs the Xtensa vector table by writing its address
targets/esp32s3-interrupts.S
+95 -28
View File
@@ -173,7 +173,7 @@ _nmi_vector:
// -----------------------------------------------------------------------
// Offset 0x300 — Kernel exception
// Diagnostic: steady 1s ON / 1s OFF blink.
// Writes EXCCAUSE+EPC1 to RTC STORE regs, then triggers software reset.
// -----------------------------------------------------------------------
.org _vector_table + 0x300
_kernel_vector:
@@ -192,17 +192,39 @@ _level1_vector:
// -----------------------------------------------------------------------
// Offset 0x3C0 — Double exception
// Diagnostic: solid LED ON (no blinking).
// Diagnostic: write magic to RTC STORE regs, then halt.
// RTC_CNTL_STORE0 = 0x60008050, STORE1 = 0x60008054
// -----------------------------------------------------------------------
.org _vector_table + 0x3C0
_double_vector:
movi a0, 1
slli a0, a0, 21
movi a1, 6
slli a1, a1, 28
addmi a1, a1, 0x4000
s32i a0, a1, 0x0C // LED ON permanently
1: j 1b // spin forever
// Write 0x55550000 + EXCCAUSE to RTC_CNTL_STORE0 (0x60008050)
// Build address: 0x60008050 = 6<<28 + 0x4000 + 0x4000 + 0x50
movi a0, 6
slli a0, a0, 28 // a0 = 0x60000000
addmi a0, a0, 0x4000 // a0 = 0x60004000
addmi a0, a0, 0x4000 // a0 = 0x60008000
addi a0, a0, 0x50 // a0 = 0x60008050
rsr a1, EXCCAUSE
movi a2, 0x555
slli a2, a2, 20 // a2 = 0x55500000
movi a3, 5
slli a3, a3, 16 // a3 = 0x00050000
or a2, a2, a3 // a2 = 0x55550000
or a1, a2, a1 // a1 = 0x5555xxxx
s32i a1, a0, 0 // STORE0
rsr a1, DEPC
s32i a1, a0, 4 // STORE1 = DEPC
rsr a1, EPC1
s32i a1, a0, 8 // STORE2 = EPC1
// Trigger software system reset (preserves RTC STORE regs).
// RTC_CNTL_OPTIONS0_REG = 0x60008000, bit 31 = SW_SYS_RST
addi a0, a0, -0x50 // a0 = 0x60008000
l32i a1, a0, 0
movi a2, 1
slli a2, a2, 31
or a1, a1, a2
s32i a1, a0, 0 // trigger reset
1: j 1b // wait for reset
// -----------------------------------------------------------------------
// Level-1 interrupt handler — lives outside the vector table so there
@@ -232,6 +254,13 @@ _double_vector:
.balign 4
.LhandleInterrupt_addr:
.word handleInterrupt
.Luser_exception_addr:
.word espradio_user_exception
// Make espradio_user_exception a weak reference so programs that don't
// link espradio (e.g. blinky) still build. The default handler below
// is used when no strong definition is provided.
.weak espradio_user_exception
// -----------------------------------------------------------------------
// Kernel exception handler (out-of-table).
@@ -243,25 +272,30 @@ _double_vector:
// 29 blinks = cause 28 (LoadProhibitedCause)
// -----------------------------------------------------------------------
_handle_kernel_exc:
// Steady 1-second ON / 1-second OFF blink.
// This is the KERNEL exception handler.
movi a0, 1
slli a0, a0, 21 // a0 = GPIO21 bit
movi a1, 6
slli a1, a1, 28
addmi a1, a1, 0x4000 // a1 = 0x60004000
_hke_blink:
s32i a0, a1, 0x0C // LED ON
movi a2, 5
slli a2, a2, 23 // ~1s @40MHz
1: addi a2, a2, -1
bnez a2, 1b
s32i a0, a1, 0x08 // LED OFF
movi a2, 5
slli a2, a2, 23 // ~1s @40MHz
1: addi a2, a2, -1
bnez a2, 1b
j _hke_blink
// Write 0x55560000 + EXCCAUSE to RTC_CNTL_STORE0 (0x60008050)
movi a0, 6
slli a0, a0, 28
addmi a0, a0, 0x4000
addmi a0, a0, 0x4000
addi a0, a0, 0x50 // a0 = 0x60008050
rsr a1, EXCCAUSE
movi a2, 0x555
slli a2, a2, 20
movi a3, 6
slli a3, a3, 16
or a2, a2, a3 // a2 = 0x55560000
or a1, a2, a1
s32i a1, a0, 0 // STORE0
rsr a1, EPC1
s32i a1, a0, 4 // STORE1 = EPC1
// Trigger software system reset (preserves RTC STORE regs).
addi a0, a0, -0x50 // a0 = 0x60008000
l32i a1, a0, 0
movi a2, 1
slli a2, a2, 31
or a1, a1, a2
s32i a1, a0, 0 // trigger reset
1: j 1b // wait for reset
.global _handle_level1
_handle_level1:
@@ -312,6 +346,26 @@ _handle_level1:
wsr a2, PS
rsync
// Check if this is an exception (not an interrupt).
// EXCCAUSE == 4 means level-1 interrupt; anything else is an exception.
rsr a2, EXCCAUSE
movi a3, 4
beq a2, a3, .Lis_interrupt
// --- It's an exception, not an interrupt ---
// Call the C exception handler: espradio_user_exception(cause, epc, excvaddr, frame)
// Using callx4 (same convention as handleInterrupt).
mov a6, a2 // a6 = EXCCAUSE (will be a2 after window rotate)
l32i a7, a1, 68 // a7 = EPC1 (saved earlier)
rsr a8, EXCVADDR // a8 = faulting address
mov a9, a1 // a9 = frame pointer (callee a5)
mov a5, a1 // callee stack
l32r a2, .Luser_exception_addr
callx4 a2
// Does not return — loops forever in the C handler.
.Lis_interrupt:
// Call the Go interrupt dispatcher via callx4.
// callx4 explicitly sets PS.CALLINC=1 and puts the return address
// (with top 2 bits = 01) in a4. After entry rotates the window by
@@ -357,3 +411,16 @@ _handle_level1:
l32i a1, a1, 4 // restores original SP (deallocates frame)
rfe
// -----------------------------------------------------------------------
// Default weak espradio_user_exception: infinite loop halt.
// Overridden by the strong definition in espradio's isr.c when linked.
// -----------------------------------------------------------------------
.section .iram1, "ax"
.balign 4
.weak espradio_user_exception
.type espradio_user_exception, @function
espradio_user_exception:
waiti 0
j espradio_user_exception
.size espradio_user_exception, . - espradio_user_exception
targets/esp32s3.json
+7
View File
@@ -7,6 +7,13 @@
"scheduler": "tasks",
"serial": "usb",
"linker": "ld.lld",
"ldflags": [
"--wrap=malloc",
"--wrap=calloc",
"--wrap=free",
"--wrap=realloc",
"--wrap=ppCheckTxConnTrafficIdle"
],
"default-stack-size": 8192,
"rtlib": "compiler-rt",
"libc": "picolibc",