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Date: Mon, 17 Oct 2022 14:53:33 -0000
From: "tip-bot2 for Thomas Gleixner" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Thomas Gleixner <tglx@...utronix.de>,
"Peter Zijlstra (Intel)" <peterz@...radead.org>, x86@...nel.org,
linux-kernel@...r.kernel.org
Subject: [tip: x86/core] x86/bpf: Emit call depth accounting if required
The following commit has been merged into the x86/core branch of tip:
Commit-ID: b2e9dfe54be4d023124d588d6f03d16a9c0d2507
Gitweb: https://git.kernel.org/tip/b2e9dfe54be4d023124d588d6f03d16a9c0d2507
Author: Thomas Gleixner <tglx@...utronix.de>
AuthorDate: Thu, 15 Sep 2022 13:11:34 +02:00
Committer: Peter Zijlstra <peterz@...radead.org>
CommitterDate: Mon, 17 Oct 2022 16:41:18 +02:00
x86/bpf: Emit call depth accounting if required
Ensure that calls in BPF jitted programs are emitting call depth accounting
when enabled to keep the call/return balanced. The return thunk jump is
already injected due to the earlier retbleed mitigations.
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Link: https://lore.kernel.org/r/20220915111148.615413406@infradead.org
---
arch/x86/include/asm/alternative.h | 6 +++++-
arch/x86/kernel/callthunks.c | 19 +++++++++++++++++-
arch/x86/net/bpf_jit_comp.c | 32 ++++++++++++++++++++---------
3 files changed, 48 insertions(+), 9 deletions(-)
diff --git a/arch/x86/include/asm/alternative.h b/arch/x86/include/asm/alternative.h
index 4b8cd25..664c077 100644
--- a/arch/x86/include/asm/alternative.h
+++ b/arch/x86/include/asm/alternative.h
@@ -93,6 +93,7 @@ extern void callthunks_patch_module_calls(struct callthunk_sites *sites,
struct module *mod);
extern void *callthunks_translate_call_dest(void *dest);
extern bool is_callthunk(void *addr);
+extern int x86_call_depth_emit_accounting(u8 **pprog, void *func);
#else
static __always_inline void callthunks_patch_builtin_calls(void) {}
static __always_inline void
@@ -106,6 +107,11 @@ static __always_inline bool is_callthunk(void *addr)
{
return false;
}
+static __always_inline int x86_call_depth_emit_accounting(u8 **pprog,
+ void *func)
+{
+ return 0;
+}
#endif
#ifdef CONFIG_SMP
diff --git a/arch/x86/kernel/callthunks.c b/arch/x86/kernel/callthunks.c
index 7f97881..a03d646 100644
--- a/arch/x86/kernel/callthunks.c
+++ b/arch/x86/kernel/callthunks.c
@@ -306,6 +306,25 @@ bool is_callthunk(void *addr)
return !bcmp((void *)(dest - tmpl_size), tmpl, tmpl_size);
}
+#ifdef CONFIG_BPF_JIT
+int x86_call_depth_emit_accounting(u8 **pprog, void *func)
+{
+ unsigned int tmpl_size = SKL_TMPL_SIZE;
+ void *tmpl = skl_call_thunk_template;
+
+ if (!thunks_initialized)
+ return 0;
+
+ /* Is function call target a thunk? */
+ if (is_callthunk(func))
+ return 0;
+
+ memcpy(*pprog, tmpl, tmpl_size);
+ *pprog += tmpl_size;
+ return tmpl_size;
+}
+#endif
+
#ifdef CONFIG_MODULES
void noinline callthunks_patch_module_calls(struct callthunk_sites *cs,
struct module *mod)
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index ad8cb7f..a6b4674 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -340,6 +340,13 @@ static int emit_call(u8 **pprog, void *func, void *ip)
return emit_patch(pprog, func, ip, 0xE8);
}
+static int emit_rsb_call(u8 **pprog, void *func, void *ip)
+{
+ OPTIMIZER_HIDE_VAR(func);
+ x86_call_depth_emit_accounting(pprog, func);
+ return emit_patch(pprog, func, ip, 0xE8);
+}
+
static int emit_jump(u8 **pprog, void *func, void *ip)
{
return emit_patch(pprog, func, ip, 0xE9);
@@ -1436,19 +1443,26 @@ st: if (is_imm8(insn->off))
break;
/* call */
- case BPF_JMP | BPF_CALL:
+ case BPF_JMP | BPF_CALL: {
+ int offs;
+
func = (u8 *) __bpf_call_base + imm32;
if (tail_call_reachable) {
/* mov rax, qword ptr [rbp - rounded_stack_depth - 8] */
EMIT3_off32(0x48, 0x8B, 0x85,
-round_up(bpf_prog->aux->stack_depth, 8) - 8);
- if (!imm32 || emit_call(&prog, func, image + addrs[i - 1] + 7))
+ if (!imm32)
return -EINVAL;
+ offs = 7 + x86_call_depth_emit_accounting(&prog, func);
} else {
- if (!imm32 || emit_call(&prog, func, image + addrs[i - 1]))
+ if (!imm32)
return -EINVAL;
+ offs = x86_call_depth_emit_accounting(&prog, func);
}
+ if (emit_call(&prog, func, image + addrs[i - 1] + offs))
+ return -EINVAL;
break;
+ }
case BPF_JMP | BPF_TAIL_CALL:
if (imm32)
@@ -1854,7 +1868,7 @@ static int invoke_bpf_prog(const struct btf_func_model *m, u8 **pprog,
/* arg2: lea rsi, [rbp - ctx_cookie_off] */
EMIT4(0x48, 0x8D, 0x75, -run_ctx_off);
- if (emit_call(&prog, enter, prog))
+ if (emit_rsb_call(&prog, enter, prog))
return -EINVAL;
/* remember prog start time returned by __bpf_prog_enter */
emit_mov_reg(&prog, true, BPF_REG_6, BPF_REG_0);
@@ -1875,7 +1889,7 @@ static int invoke_bpf_prog(const struct btf_func_model *m, u8 **pprog,
(long) p->insnsi >> 32,
(u32) (long) p->insnsi);
/* call JITed bpf program or interpreter */
- if (emit_call(&prog, p->bpf_func, prog))
+ if (emit_rsb_call(&prog, p->bpf_func, prog))
return -EINVAL;
/*
@@ -1899,7 +1913,7 @@ static int invoke_bpf_prog(const struct btf_func_model *m, u8 **pprog,
emit_mov_reg(&prog, true, BPF_REG_2, BPF_REG_6);
/* arg3: lea rdx, [rbp - run_ctx_off] */
EMIT4(0x48, 0x8D, 0x55, -run_ctx_off);
- if (emit_call(&prog, exit, prog))
+ if (emit_rsb_call(&prog, exit, prog))
return -EINVAL;
*pprog = prog;
@@ -2147,7 +2161,7 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i
if (flags & BPF_TRAMP_F_CALL_ORIG) {
/* arg1: mov rdi, im */
emit_mov_imm64(&prog, BPF_REG_1, (long) im >> 32, (u32) (long) im);
- if (emit_call(&prog, __bpf_tramp_enter, prog)) {
+ if (emit_rsb_call(&prog, __bpf_tramp_enter, prog)) {
ret = -EINVAL;
goto cleanup;
}
@@ -2179,7 +2193,7 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i
EMIT2(0xff, 0xd0); /* call *rax */
} else {
/* call original function */
- if (emit_call(&prog, orig_call, prog)) {
+ if (emit_rsb_call(&prog, orig_call, prog)) {
ret = -EINVAL;
goto cleanup;
}
@@ -2223,7 +2237,7 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i
im->ip_epilogue = prog;
/* arg1: mov rdi, im */
emit_mov_imm64(&prog, BPF_REG_1, (long) im >> 32, (u32) (long) im);
- if (emit_call(&prog, __bpf_tramp_exit, prog)) {
+ if (emit_rsb_call(&prog, __bpf_tramp_exit, prog)) {
ret = -EINVAL;
goto cleanup;
}
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