From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
stable@vger.kernel.org,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
Borislav Petkov <bp@suse.de>, Alexei Starovoitov <ast@kernel.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Subject: [PATCH 5.15 20/89] bpf,x86: Respect X86_FEATURE_RETPOLINE*
Date: Fri, 22 Jul 2022 11:10:54 +0200 [thread overview]
Message-ID: <20220722091134.502726755@linuxfoundation.org> (raw)
In-Reply-To: <20220722091133.320803732@linuxfoundation.org>
From: Peter Zijlstra <peterz@infradead.org>
commit 87c87ecd00c54ecd677798cb49ef27329e0fab41 upstream.
Current BPF codegen doesn't respect X86_FEATURE_RETPOLINE* flags and
unconditionally emits a thunk call, this is sub-optimal and doesn't
match the regular, compiler generated, code.
Update the i386 JIT to emit code equal to what the compiler emits for
the regular kernel text (IOW. a plain THUNK call).
Update the x86_64 JIT to emit code similar to the result of compiler
and kernel rewrites as according to X86_FEATURE_RETPOLINE* flags.
Inlining RETPOLINE_AMD (lfence; jmp *%reg) and !RETPOLINE (jmp *%reg),
while doing a THUNK call for RETPOLINE.
This removes the hard-coded retpoline thunks and shrinks the generated
code. Leaving a single retpoline thunk definition in the kernel.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Borislav Petkov <bp@suse.de>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Tested-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/r/20211026120310.614772675@infradead.org
[cascardo: RETPOLINE_AMD was renamed to RETPOLINE_LFENCE]
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/include/asm/nospec-branch.h | 59 -----------------------------------
arch/x86/net/bpf_jit_comp.c | 46 +++++++++++++--------------
arch/x86/net/bpf_jit_comp32.c | 22 +++++++++++--
3 files changed, 41 insertions(+), 86 deletions(-)
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -320,63 +320,4 @@ static inline void mds_idle_clear_cpu_bu
#endif /* __ASSEMBLY__ */
-/*
- * Below is used in the eBPF JIT compiler and emits the byte sequence
- * for the following assembly:
- *
- * With retpolines configured:
- *
- * callq do_rop
- * spec_trap:
- * pause
- * lfence
- * jmp spec_trap
- * do_rop:
- * mov %rcx,(%rsp) for x86_64
- * mov %edx,(%esp) for x86_32
- * retq
- *
- * Without retpolines configured:
- *
- * jmp *%rcx for x86_64
- * jmp *%edx for x86_32
- */
-#ifdef CONFIG_RETPOLINE
-# ifdef CONFIG_X86_64
-# define RETPOLINE_RCX_BPF_JIT_SIZE 17
-# define RETPOLINE_RCX_BPF_JIT() \
-do { \
- EMIT1_off32(0xE8, 7); /* callq do_rop */ \
- /* spec_trap: */ \
- EMIT2(0xF3, 0x90); /* pause */ \
- EMIT3(0x0F, 0xAE, 0xE8); /* lfence */ \
- EMIT2(0xEB, 0xF9); /* jmp spec_trap */ \
- /* do_rop: */ \
- EMIT4(0x48, 0x89, 0x0C, 0x24); /* mov %rcx,(%rsp) */ \
- EMIT1(0xC3); /* retq */ \
-} while (0)
-# else /* !CONFIG_X86_64 */
-# define RETPOLINE_EDX_BPF_JIT() \
-do { \
- EMIT1_off32(0xE8, 7); /* call do_rop */ \
- /* spec_trap: */ \
- EMIT2(0xF3, 0x90); /* pause */ \
- EMIT3(0x0F, 0xAE, 0xE8); /* lfence */ \
- EMIT2(0xEB, 0xF9); /* jmp spec_trap */ \
- /* do_rop: */ \
- EMIT3(0x89, 0x14, 0x24); /* mov %edx,(%esp) */ \
- EMIT1(0xC3); /* ret */ \
-} while (0)
-# endif
-#else /* !CONFIG_RETPOLINE */
-# ifdef CONFIG_X86_64
-# define RETPOLINE_RCX_BPF_JIT_SIZE 2
-# define RETPOLINE_RCX_BPF_JIT() \
- EMIT2(0xFF, 0xE1); /* jmp *%rcx */
-# else /* !CONFIG_X86_64 */
-# define RETPOLINE_EDX_BPF_JIT() \
- EMIT2(0xFF, 0xE2) /* jmp *%edx */
-# endif
-#endif
-
#endif /* _ASM_X86_NOSPEC_BRANCH_H_ */
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -387,6 +387,25 @@ int bpf_arch_text_poke(void *ip, enum bp
return __bpf_arch_text_poke(ip, t, old_addr, new_addr, true);
}
+#define EMIT_LFENCE() EMIT3(0x0F, 0xAE, 0xE8)
+
+static void emit_indirect_jump(u8 **pprog, int reg, u8 *ip)
+{
+ u8 *prog = *pprog;
+
+#ifdef CONFIG_RETPOLINE
+ if (cpu_feature_enabled(X86_FEATURE_RETPOLINE_LFENCE)) {
+ EMIT_LFENCE();
+ EMIT2(0xFF, 0xE0 + reg);
+ } else if (cpu_feature_enabled(X86_FEATURE_RETPOLINE)) {
+ emit_jump(&prog, &__x86_indirect_thunk_array[reg], ip);
+ } else
+#endif
+ EMIT2(0xFF, 0xE0 + reg);
+
+ *pprog = prog;
+}
+
/*
* Generate the following code:
*
@@ -468,7 +487,7 @@ static void emit_bpf_tail_call_indirect(
* rdi == ctx (1st arg)
* rcx == prog->bpf_func + X86_TAIL_CALL_OFFSET
*/
- RETPOLINE_RCX_BPF_JIT();
+ emit_indirect_jump(&prog, 1 /* rcx */, ip + (prog - start));
/* out: */
ctx->tail_call_indirect_label = prog - start;
@@ -1185,8 +1204,7 @@ static int do_jit(struct bpf_prog *bpf_p
/* speculation barrier */
case BPF_ST | BPF_NOSPEC:
if (boot_cpu_has(X86_FEATURE_XMM2))
- /* Emit 'lfence' */
- EMIT3(0x0F, 0xAE, 0xE8);
+ EMIT_LFENCE();
break;
/* ST: *(u8*)(dst_reg + off) = imm */
@@ -2122,24 +2140,6 @@ cleanup:
return ret;
}
-static int emit_fallback_jump(u8 **pprog)
-{
- u8 *prog = *pprog;
- int err = 0;
-
-#ifdef CONFIG_RETPOLINE
- /* Note that this assumes the the compiler uses external
- * thunks for indirect calls. Both clang and GCC use the same
- * naming convention for external thunks.
- */
- err = emit_jump(&prog, __x86_indirect_thunk_rdx, prog);
-#else
- EMIT2(0xFF, 0xE2); /* jmp rdx */
-#endif
- *pprog = prog;
- return err;
-}
-
static int emit_bpf_dispatcher(u8 **pprog, int a, int b, s64 *progs)
{
u8 *jg_reloc, *prog = *pprog;
@@ -2161,9 +2161,7 @@ static int emit_bpf_dispatcher(u8 **ppro
if (err)
return err;
- err = emit_fallback_jump(&prog); /* jmp thunk/indirect */
- if (err)
- return err;
+ emit_indirect_jump(&prog, 2 /* rdx */, prog);
*pprog = prog;
return 0;
--- a/arch/x86/net/bpf_jit_comp32.c
+++ b/arch/x86/net/bpf_jit_comp32.c
@@ -15,6 +15,7 @@
#include <asm/cacheflush.h>
#include <asm/set_memory.h>
#include <asm/nospec-branch.h>
+#include <asm/asm-prototypes.h>
#include <linux/bpf.h>
/*
@@ -1267,6 +1268,21 @@ static void emit_epilogue(u8 **pprog, u3
*pprog = prog;
}
+static int emit_jmp_edx(u8 **pprog, u8 *ip)
+{
+ u8 *prog = *pprog;
+ int cnt = 0;
+
+#ifdef CONFIG_RETPOLINE
+ EMIT1_off32(0xE9, (u8 *)__x86_indirect_thunk_edx - (ip + 5));
+#else
+ EMIT2(0xFF, 0xE2);
+#endif
+ *pprog = prog;
+
+ return cnt;
+}
+
/*
* Generate the following code:
* ... bpf_tail_call(void *ctx, struct bpf_array *array, u64 index) ...
@@ -1280,7 +1296,7 @@ static void emit_epilogue(u8 **pprog, u3
* goto *(prog->bpf_func + prologue_size);
* out:
*/
-static void emit_bpf_tail_call(u8 **pprog)
+static void emit_bpf_tail_call(u8 **pprog, u8 *ip)
{
u8 *prog = *pprog;
int cnt = 0;
@@ -1362,7 +1378,7 @@ static void emit_bpf_tail_call(u8 **ppro
* eax == ctx (1st arg)
* edx == prog->bpf_func + prologue_size
*/
- RETPOLINE_EDX_BPF_JIT();
+ cnt += emit_jmp_edx(&prog, ip + cnt);
if (jmp_label1 == -1)
jmp_label1 = cnt;
@@ -2122,7 +2138,7 @@ static int do_jit(struct bpf_prog *bpf_p
break;
}
case BPF_JMP | BPF_TAIL_CALL:
- emit_bpf_tail_call(&prog);
+ emit_bpf_tail_call(&prog, image + addrs[i - 1]);
break;
/* cond jump */
next prev parent reply other threads:[~2022-07-22 9:21 UTC|newest]
Thread overview: 96+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-22 9:10 [PATCH 5.15 00/89] 5.15.57-rc1 review Greg Kroah-Hartman
2022-07-22 9:10 ` [PATCH 5.15 01/89] x86/traps: Use pt_regs directly in fixup_bad_iret() Greg Kroah-Hartman
2022-07-22 9:10 ` [PATCH 5.15 02/89] x86/entry: Switch the stack after error_entry() returns Greg Kroah-Hartman
2022-07-22 9:10 ` [PATCH 5.15 03/89] x86/entry: Move PUSH_AND_CLEAR_REGS out of error_entry() Greg Kroah-Hartman
2022-07-22 9:10 ` [PATCH 5.15 04/89] x86/entry: Dont call error_entry() for XENPV Greg Kroah-Hartman
2022-07-22 9:10 ` [PATCH 5.15 05/89] objtool: Classify symbols Greg Kroah-Hartman
2022-07-22 9:10 ` [PATCH 5.15 06/89] objtool: Explicitly avoid self modifying code in .altinstr_replacement Greg Kroah-Hartman
2022-07-22 9:10 ` [PATCH 5.15 07/89] objtool: Shrink struct instruction Greg Kroah-Hartman
2022-07-22 9:10 ` [PATCH 5.15 08/89] objtool,x86: Replace alternatives with .retpoline_sites Greg Kroah-Hartman
2022-07-22 9:10 ` [PATCH 5.15 09/89] objtool: Introduce CFI hash Greg Kroah-Hartman
2022-07-22 9:10 ` [PATCH 5.15 10/89] x86/retpoline: Remove unused replacement symbols Greg Kroah-Hartman
2022-07-22 9:10 ` [PATCH 5.15 11/89] x86/asm: Fix register order Greg Kroah-Hartman
2022-07-22 9:10 ` [PATCH 5.15 12/89] x86/asm: Fixup odd GEN-for-each-reg.h usage Greg Kroah-Hartman
2022-07-22 9:10 ` [PATCH 5.15 13/89] x86/retpoline: Move the retpoline thunk declarations to nospec-branch.h Greg Kroah-Hartman
2022-07-22 9:10 ` [PATCH 5.15 14/89] x86/retpoline: Create a retpoline thunk array Greg Kroah-Hartman
2022-07-22 9:10 ` [PATCH 5.15 15/89] x86/alternative: Implement .retpoline_sites support Greg Kroah-Hartman
2022-07-22 9:10 ` [PATCH 5.15 16/89] x86/alternative: Handle Jcc __x86_indirect_thunk_\reg Greg Kroah-Hartman
2022-07-22 9:10 ` [PATCH 5.15 17/89] x86/alternative: Try inline spectre_v2=retpoline,amd Greg Kroah-Hartman
2022-07-22 9:10 ` [PATCH 5.15 18/89] x86/alternative: Add debug prints to apply_retpolines() Greg Kroah-Hartman
2022-07-22 9:10 ` [PATCH 5.15 19/89] bpf,x86: Simplify computing label offsets Greg Kroah-Hartman
2022-07-22 9:10 ` Greg Kroah-Hartman [this message]
2022-07-22 9:10 ` [PATCH 5.15 21/89] objtool: Default ignore INT3 for unreachable Greg Kroah-Hartman
2022-07-22 9:10 ` [PATCH 5.15 22/89] x86/entry: Remove skip_r11rcx Greg Kroah-Hartman
2022-07-22 9:10 ` [PATCH 5.15 23/89] x86/realmode: build with -D__DISABLE_EXPORTS Greg Kroah-Hartman
2022-07-22 9:10 ` [PATCH 5.15 24/89] x86/kvm/vmx: Make noinstr clean Greg Kroah-Hartman
2022-07-22 9:10 ` [PATCH 5.15 25/89] x86/cpufeatures: Move RETPOLINE flags to word 11 Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 26/89] x86/retpoline: Cleanup some #ifdefery Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 27/89] x86/retpoline: Swizzle retpoline thunk Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 28/89] x86/retpoline: Use -mfunction-return Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 29/89] x86: Undo return-thunk damage Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 30/89] x86,objtool: Create .return_sites Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 31/89] objtool: skip non-text sections when adding return-thunk sites Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 32/89] x86,static_call: Use alternative RET encoding Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 33/89] x86/ftrace: " Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 34/89] x86/bpf: " Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 35/89] x86/kvm: Fix SETcc emulation for return thunks Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 36/89] x86/vsyscall_emu/64: Dont use RET in vsyscall emulation Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 37/89] x86/sev: Avoid using __x86_return_thunk Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 38/89] x86: Use return-thunk in asm code Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 39/89] x86/entry: Avoid very early RET Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 40/89] objtool: Treat .text.__x86.* as noinstr Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 41/89] x86: Add magic AMD return-thunk Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 42/89] x86/bugs: Report AMD retbleed vulnerability Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 43/89] x86/bugs: Add AMD retbleed= boot parameter Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 44/89] x86/bugs: Enable STIBP for JMP2RET Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 45/89] x86/bugs: Keep a per-CPU IA32_SPEC_CTRL value Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 46/89] x86/entry: Add kernel IBRS implementation Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 47/89] x86/bugs: Optimize SPEC_CTRL MSR writes Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 48/89] x86/speculation: Add spectre_v2=ibrs option to support Kernel IBRS Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 49/89] x86/bugs: Split spectre_v2_select_mitigation() and spectre_v2_user_select_mitigation() Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 50/89] x86/bugs: Report Intel retbleed vulnerability Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 51/89] intel_idle: Disable IBRS during long idle Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 52/89] objtool: Update Retpoline validation Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 53/89] x86/xen: Rename SYS* entry points Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 54/89] x86/xen: Add UNTRAIN_RET Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 55/89] x86/bugs: Add retbleed=ibpb Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 56/89] x86/bugs: Do IBPB fallback check only once Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 57/89] objtool: Add entry UNRET validation Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 58/89] x86/cpu/amd: Add Spectral Chicken Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 59/89] x86/speculation: Fix RSB filling with CONFIG_RETPOLINE=n Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 60/89] x86/speculation: Fix firmware entry SPEC_CTRL handling Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 61/89] x86/speculation: Fix SPEC_CTRL write on SMT state change Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 62/89] x86/speculation: Use cached host SPEC_CTRL value for guest entry/exit Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 63/89] x86/speculation: Remove x86_spec_ctrl_mask Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 64/89] objtool: Re-add UNWIND_HINT_{SAVE_RESTORE} Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 65/89] KVM: VMX: Flatten __vmx_vcpu_run() Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 66/89] KVM: VMX: Convert launched argument to flags Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 67/89] KVM: VMX: Prevent guest RSB poisoning attacks with eIBRS Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 68/89] KVM: VMX: Fix IBRS handling after vmexit Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 69/89] x86/speculation: Fill RSB on vmexit for IBRS Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 70/89] x86/common: Stamp out the stepping madness Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 71/89] x86/cpu/amd: Enumerate BTC_NO Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 72/89] x86/retbleed: Add fine grained Kconfig knobs Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 73/89] x86/bugs: Add Cannon lake to RETBleed affected CPU list Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 74/89] x86/entry: Move PUSH_AND_CLEAR_REGS() back into error_entry Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 75/89] x86/bugs: Do not enable IBPB-on-entry when IBPB is not supported Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 76/89] x86/kexec: Disable RET on kexec Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 77/89] x86/speculation: Disable RRSBA behavior Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 78/89] x86/static_call: Serialize __static_call_fixup() properly Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 79/89] x86/xen: Fix initialisation in hypercall_page after rethunk Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 80/89] x86/asm/32: Fix ANNOTATE_UNRET_SAFE use on 32-bit Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 81/89] x86/speculation: Use DECLARE_PER_CPU for x86_spec_ctrl_current Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 82/89] efi/x86: use naked RET on mixed mode call wrapper Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 83/89] x86/kvm: fix FASTOP_SIZE when return thunks are enabled Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 84/89] KVM: emulate: do not adjust size of fastop and setcc subroutines Greg Kroah-Hartman
2022-07-22 9:11 ` [PATCH 5.15 85/89] tools arch x86: Sync the msr-index.h copy with the kernel sources Greg Kroah-Hartman
2022-07-22 9:12 ` [PATCH 5.15 86/89] tools headers cpufeatures: Sync " Greg Kroah-Hartman
2022-07-22 9:12 ` [PATCH 5.15 87/89] x86/bugs: Remove apostrophe typo Greg Kroah-Hartman
2022-07-22 9:12 ` [PATCH 5.15 88/89] um: Add missing apply_returns() Greg Kroah-Hartman
2022-07-22 9:12 ` [PATCH 5.15 89/89] x86: Use -mindirect-branch-cs-prefix for RETPOLINE builds Greg Kroah-Hartman
2022-07-22 12:14 ` [PATCH 5.15 00/89] 5.15.57-rc1 review Bagas Sanjaya
2022-07-22 17:58 ` Florian Fainelli
2022-07-22 19:36 ` Naresh Kamboju
2022-07-22 21:59 ` Guenter Roeck
2022-07-23 4:21 ` Ron Economos
2022-07-23 8:55 ` Sudip Mukherjee (Codethink)
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