git: 2517b2085b58 - main - kinst: use per-probe trampolines in riscv
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Date: Wed, 19 Jul 2023 14:59:53 UTC
The branch main has been updated by christos:
URL: https://cgit.FreeBSD.org/src/commit/?id=2517b2085b58e0ca4837faecd94b91ad80872547
commit 2517b2085b58e0ca4837faecd94b91ad80872547
Author: Christos Margiolis <christos@FreeBSD.org>
AuthorDate: 2023-07-19 14:57:59 +0000
Commit: Christos Margiolis <christos@FreeBSD.org>
CommitDate: 2023-07-19 14:57:59 +0000
kinst: use per-probe trampolines in riscv
Reviewed by: markj
Approved by: markj (mentor)
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D40963
---
sys/cddl/dev/kinst/riscv/kinst_isa.c | 113 +++++++++++++----------------------
1 file changed, 42 insertions(+), 71 deletions(-)
diff --git a/sys/cddl/dev/kinst/riscv/kinst_isa.c b/sys/cddl/dev/kinst/riscv/kinst_isa.c
index 8bd4449a027a..9c1f4a239f83 100644
--- a/sys/cddl/dev/kinst/riscv/kinst_isa.c
+++ b/sys/cddl/dev/kinst/riscv/kinst_isa.c
@@ -14,20 +14,7 @@
#include "kinst.h"
-/*
- * Per-CPU trampolines used when the interrupted thread is executing with
- * interrupts disabled. If an interrupt is raised while executing a trampoline,
- * the interrupt thread cannot safely overwrite its trampoline if it hits a
- * kinst probe while executing the interrupt handler.
- */
-DPCPU_DEFINE_STATIC(uint8_t *, intr_tramp);
-
-/*
- * The double-breakpoint mechanism needs to save the current probe for the next
- * call to kinst_invop(). As with per-CPU trampolines, this also has to be done
- * per-CPU when interrupts are disabled.
- */
-DPCPU_DEFINE_STATIC(struct kinst_probe *, intr_probe);
+DPCPU_DEFINE_STATIC(struct kinst_cpu_state, kinst_state);
#define _MATCH_REG(reg) \
(offsetof(struct trapframe, tf_ ## reg) / sizeof(register_t))
@@ -78,7 +65,7 @@ kinst_c_regoff(struct trapframe *frame, int n)
#undef _MATCH_REG
static int
-kinst_emulate(struct trapframe *frame, struct kinst_probe *kp)
+kinst_emulate(struct trapframe *frame, const struct kinst_probe *kp)
{
kinst_patchval_t instr = kp->kp_savedval;
register_t prevpc;
@@ -244,23 +231,23 @@ kinst_emulate(struct trapframe *frame, struct kinst_probe *kp)
}
static int
-kinst_jump_next_instr(struct trapframe *frame, struct kinst_probe *kp)
+kinst_jump_next_instr(struct trapframe *frame, const struct kinst_probe *kp)
{
- frame->tf_sepc = (register_t)((uint8_t *)kp->kp_patchpoint +
+ frame->tf_sepc = (register_t)((const uint8_t *)kp->kp_patchpoint +
kp->kp_md.instlen);
return (MATCH_C_NOP);
}
static void
-kinst_trampoline_populate(struct kinst_probe *kp, uint8_t *tramp)
+kinst_trampoline_populate(struct kinst_probe *kp)
{
static uint16_t nop = MATCH_C_NOP;
static uint32_t ebreak = MATCH_EBREAK;
int ilen;
ilen = kp->kp_md.instlen;
- kinst_memcpy(tramp, &kp->kp_savedval, ilen);
+ kinst_memcpy(kp->kp_tramp, &kp->kp_savedval, ilen);
/*
* Since we cannot encode large displacements in a single instruction
@@ -273,9 +260,9 @@ kinst_trampoline_populate(struct kinst_probe *kp, uint8_t *tramp)
* Add a NOP after a compressed instruction for padding.
*/
if (ilen == INSN_C_SIZE)
- kinst_memcpy(&tramp[ilen], &nop, INSN_C_SIZE);
+ kinst_memcpy(&kp->kp_tramp[ilen], &nop, INSN_C_SIZE);
- kinst_memcpy(&tramp[INSN_SIZE], &ebreak, INSN_SIZE);
+ kinst_memcpy(&kp->kp_tramp[INSN_SIZE], &ebreak, INSN_SIZE);
fence_i();
}
@@ -306,27 +293,26 @@ int
kinst_invop(uintptr_t addr, struct trapframe *frame, uintptr_t scratch)
{
solaris_cpu_t *cpu;
- struct kinst_probe *kp;
- uint8_t *tramp;
+ struct kinst_cpu_state *ks;
+ const struct kinst_probe *kp;
- /*
- * Use per-CPU trampolines and probes if the thread executing the
- * instruction was executing with interrupts disabled.
- */
- if ((frame->tf_sstatus & SSTATUS_SPIE) == 0) {
- tramp = DPCPU_GET(intr_tramp);
- kp = DPCPU_GET(intr_probe);
- } else {
- tramp = curthread->t_kinst_tramp;
- kp = curthread->t_kinst_curprobe;
- }
+ ks = DPCPU_PTR(kinst_state);
/*
* Detect if the breakpoint was triggered by the trampoline, and
* manually set the PC to the next instruction.
*/
- if (addr == (uintptr_t)(tramp + INSN_SIZE))
- return (kinst_jump_next_instr(frame, kp));
+ if (ks->state == KINST_PROBE_FIRED &&
+ addr == (uintptr_t)(ks->kp->kp_tramp + INSN_SIZE)) {
+ /*
+ * Restore interrupts if they were enabled prior to the first
+ * breakpoint.
+ */
+ if ((ks->status & SSTATUS_SPIE) != 0)
+ frame->tf_sstatus |= SSTATUS_SPIE;
+ ks->state = KINST_PROBE_ARMED;
+ return (kinst_jump_next_instr(frame, ks->kp));
+ }
LIST_FOREACH(kp, KINST_GETPROBE(addr), kp_hashnext) {
if ((uintptr_t)kp->kp_patchpoint == addr)
@@ -343,26 +329,16 @@ kinst_invop(uintptr_t addr, struct trapframe *frame, uintptr_t scratch)
if (kp->kp_md.emulate)
return (kinst_emulate(frame, kp));
- if (tramp == NULL) {
- /*
- * A trampoline allocation failed, so this probe is
- * effectively disabled. Restore the original
- * instruction.
- *
- * We can't safely print anything here, but the
- * trampoline allocator should have left a breadcrumb in
- * the dmesg.
- */
- kinst_patch_tracepoint(kp, kp->kp_savedval);
- frame->tf_sepc = (register_t)kp->kp_patchpoint;
- } else {
- kinst_trampoline_populate(kp, tramp);
- frame->tf_sepc = (register_t)tramp;
- if ((frame->tf_sstatus & SSTATUS_SPIE) == 0)
- DPCPU_SET(intr_probe, kp);
- else
- curthread->t_kinst_curprobe = kp;
- }
+ ks->state = KINST_PROBE_FIRED;
+ ks->kp = kp;
+
+ /*
+ * Cache the current SSTATUS and clear interrupts for the
+ * duration of the double breakpoint.
+ */
+ ks->status = frame->tf_sstatus;
+ frame->tf_sstatus &= ~SSTATUS_SPIE;
+ frame->tf_sepc = (register_t)kp->kp_tramp;
return (MATCH_C_NOP);
}
@@ -427,6 +403,9 @@ kinst_instr_dissect(struct kinst_probe *kp, int instrsize)
break;
}
}
+
+ if (!kpmd->emulate)
+ kinst_trampoline_populate(kp);
}
static bool
@@ -556,6 +535,10 @@ kinst_make_probe(linker_file_t lf, int symindx, linker_symval_t *symval,
kp->kp_patchval = KINST_PATCHVAL;
else
kp->kp_patchval = KINST_C_PATCHVAL;
+ if ((kp->kp_tramp = kinst_trampoline_alloc(M_WAITOK)) == NULL) {
+ KINST_LOG("cannot allocate trampoline for %p", instr);
+ return (ENOMEM);
+ }
kinst_instr_dissect(kp, instrsize);
kinst_probe_create(kp, lf);
@@ -571,14 +554,12 @@ cont:
int
kinst_md_init(void)
{
- uint8_t *tramp;
+ struct kinst_cpu_state *ks;
int cpu;
CPU_FOREACH(cpu) {
- tramp = kinst_trampoline_alloc(M_WAITOK);
- if (tramp == NULL)
- return (ENOMEM);
- DPCPU_ID_SET(cpu, intr_tramp, tramp);
+ ks = DPCPU_PTR(kinst_state);
+ ks->state = KINST_PROBE_ARMED;
}
return (0);
@@ -587,16 +568,6 @@ kinst_md_init(void)
void
kinst_md_deinit(void)
{
- uint8_t *tramp;
- int cpu;
-
- CPU_FOREACH(cpu) {
- tramp = DPCPU_ID_GET(cpu, intr_tramp);
- if (tramp != NULL) {
- kinst_trampoline_dealloc(tramp);
- DPCPU_ID_SET(cpu, intr_tramp, NULL);
- }
- }
}
/*