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Message-Id: <20250131104129.11052-2-ink@unseen.parts>
Date: Fri, 31 Jan 2025 11:41:26 +0100
From: Ivan Kokshaysky <ink@...een.parts>
To: Richard Henderson <richard.henderson@...aro.org>,
Matt Turner <mattst88@...il.com>,
Oleg Nesterov <oleg@...hat.com>,
Al Viro <viro@...iv.linux.org.uk>,
Arnd Bergmann <arnd@...db.de>,
"Paul E. McKenney" <paulmck@...nel.org>
Cc: "Maciej W. Rozycki" <macro@...am.me.uk>,
Magnus Lindholm <linmag7@...il.com>,
John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>,
linux-alpha@...r.kernel.org,
linux-kernel@...r.kernel.org,
stable@...r.kernel.org
Subject: [PATCH v2 1/4] alpha/uapi: do not expose kernel-only stack frame structures
Parts of asm/ptrace.h went into UAPI with commit 96433f6ee490
("UAPI: (Scripted) Disintegrate arch/alpha/include/asm") back in 2012.
At first glance it looked correct, as many other architectures expose
'struct pt_regs' for ptrace(2) PTRACE_GETREGS/PTRACE_SETREGS requests
and bpf(2) BPF_PROG_TYPE_KPROBE/BPF_PROG_TYPE_PERF_EVENT program
types.
On Alpha, however, these requests have never been implemented;
'struct pt_regs' describes internal kernel stack frame which has
nothing to do with userspace. Same applies to 'struct switch_stack',
as PTRACE_GETFPREG/PTRACE_SETFPREG are not implemented either.
Move this stuff back into internal asm, where we can ajust it
without causing a lot of confusion about possible UAPI breakage.
Cc: stable@...r.kernel.org
Fixes: 96433f6ee490 ("UAPI: (Scripted) Disintegrate arch/alpha/include/asm")
Signed-off-by: Ivan Kokshaysky <ink@...een.parts>
---
arch/alpha/include/asm/ptrace.h | 62 +++++++++++++++++++++++++-
arch/alpha/include/uapi/asm/ptrace.h | 65 ++--------------------------
2 files changed, 64 insertions(+), 63 deletions(-)
diff --git a/arch/alpha/include/asm/ptrace.h b/arch/alpha/include/asm/ptrace.h
index 3557ce64ed21..693d4c5b4dc7 100644
--- a/arch/alpha/include/asm/ptrace.h
+++ b/arch/alpha/include/asm/ptrace.h
@@ -2,8 +2,68 @@
#ifndef _ASMAXP_PTRACE_H
#define _ASMAXP_PTRACE_H
-#include <uapi/asm/ptrace.h>
+/*
+ * This struct defines the way the registers are stored on the
+ * kernel stack during a system call or other kernel entry
+ *
+ * NOTE! I want to minimize the overhead of system calls, so this
+ * struct has as little information as possible. It does not have
+ *
+ * - floating point regs: the kernel doesn't change those
+ * - r9-15: saved by the C compiler
+ *
+ * This makes "fork()" and "exec()" a bit more complex, but should
+ * give us low system call latency.
+ */
+struct pt_regs {
+ unsigned long r0;
+ unsigned long r1;
+ unsigned long r2;
+ unsigned long r3;
+ unsigned long r4;
+ unsigned long r5;
+ unsigned long r6;
+ unsigned long r7;
+ unsigned long r8;
+ unsigned long r19;
+ unsigned long r20;
+ unsigned long r21;
+ unsigned long r22;
+ unsigned long r23;
+ unsigned long r24;
+ unsigned long r25;
+ unsigned long r26;
+ unsigned long r27;
+ unsigned long r28;
+ unsigned long hae;
+/* JRP - These are the values provided to a0-a2 by PALcode */
+ unsigned long trap_a0;
+ unsigned long trap_a1;
+ unsigned long trap_a2;
+/* These are saved by PAL-code: */
+ unsigned long ps;
+ unsigned long pc;
+ unsigned long gp;
+ unsigned long r16;
+ unsigned long r17;
+ unsigned long r18;
+};
+
+/*
+ * This is the extended stack used by signal handlers and the context
+ * switcher: it's pushed after the normal "struct pt_regs".
+ */
+struct switch_stack {
+ unsigned long r9;
+ unsigned long r10;
+ unsigned long r11;
+ unsigned long r12;
+ unsigned long r13;
+ unsigned long r14;
+ unsigned long r15;
+ unsigned long r26;
+};
#define arch_has_single_step() (1)
#define user_mode(regs) (((regs)->ps & 8) != 0)
diff --git a/arch/alpha/include/uapi/asm/ptrace.h b/arch/alpha/include/uapi/asm/ptrace.h
index 5ca45934fcbb..ad55dc283d8d 100644
--- a/arch/alpha/include/uapi/asm/ptrace.h
+++ b/arch/alpha/include/uapi/asm/ptrace.h
@@ -2,72 +2,13 @@
#ifndef _UAPI_ASMAXP_PTRACE_H
#define _UAPI_ASMAXP_PTRACE_H
-
/*
- * This struct defines the way the registers are stored on the
- * kernel stack during a system call or other kernel entry
- *
- * NOTE! I want to minimize the overhead of system calls, so this
- * struct has as little information as possible. It does not have
- *
- * - floating point regs: the kernel doesn't change those
- * - r9-15: saved by the C compiler
+ * We don't HAVE_REGS_AND_STACK_ACCESS_API.
*
- * This makes "fork()" and "exec()" a bit more complex, but should
- * give us low system call latency.
+ * Provide empty pt_regs structure for libbpf and the likes
+ * to avoid breaking the compilation.
*/
-
struct pt_regs {
- unsigned long r0;
- unsigned long r1;
- unsigned long r2;
- unsigned long r3;
- unsigned long r4;
- unsigned long r5;
- unsigned long r6;
- unsigned long r7;
- unsigned long r8;
- unsigned long r19;
- unsigned long r20;
- unsigned long r21;
- unsigned long r22;
- unsigned long r23;
- unsigned long r24;
- unsigned long r25;
- unsigned long r26;
- unsigned long r27;
- unsigned long r28;
- unsigned long hae;
-/* JRP - These are the values provided to a0-a2 by PALcode */
- unsigned long trap_a0;
- unsigned long trap_a1;
- unsigned long trap_a2;
-/* These are saved by PAL-code: */
- unsigned long ps;
- unsigned long pc;
- unsigned long gp;
- unsigned long r16;
- unsigned long r17;
- unsigned long r18;
};
-/*
- * This is the extended stack used by signal handlers and the context
- * switcher: it's pushed after the normal "struct pt_regs".
- */
-struct switch_stack {
- unsigned long r9;
- unsigned long r10;
- unsigned long r11;
- unsigned long r12;
- unsigned long r13;
- unsigned long r14;
- unsigned long r15;
- unsigned long r26;
-#ifndef __KERNEL__
- unsigned long fp[32]; /* fp[31] is fpcr */
-#endif
-};
-
-
#endif /* _UAPI_ASMAXP_PTRACE_H */
--
2.39.5
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