From: Nicholas Piggin <npiggin@gmail.com>
To: linuxppc-dev@lists.ozlabs.org
Cc: Nicholas Piggin <npiggin@gmail.com>
Subject: [RFC PATCH 19/19] powerpc/64: ELFv2 use reserved word in the stack frame for the regs marker
Date: Mon, 31 Oct 2022 15:54:40 +1000 [thread overview]
Message-ID: <20221031055440.3594315-20-npiggin@gmail.com> (raw)
In-Reply-To: <20221031055440.3594315-1-npiggin@gmail.com>
There are 4 unused bytes in the minimum frame in the ELFv2 ABI. At the
risk of causing a future ABI incompatibility, use this and save 16 bytes
from interrupt and switch frames.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
arch/powerpc/include/asm/ptrace.h | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)
diff --git a/arch/powerpc/include/asm/ptrace.h b/arch/powerpc/include/asm/ptrace.h
index ab41d47761c9..cc308dce7ace 100644
--- a/arch/powerpc/include/asm/ptrace.h
+++ b/arch/powerpc/include/asm/ptrace.h
@@ -121,11 +121,16 @@ struct pt_regs
#ifdef CONFIG_PPC64_ELF_ABI_V2
#define STACK_FRAME_MIN_SIZE 32
-#define STACK_USER_INT_FRAME_SIZE (sizeof(struct pt_regs) + STACK_FRAME_MIN_SIZE + 16)
-#define STACK_INT_FRAME_REGS (STACK_FRAME_MIN_SIZE + 16)
-#define STACK_INT_FRAME_MARKER STACK_FRAME_MIN_SIZE
-#define STACK_SWITCH_FRAME_SIZE (sizeof(struct pt_regs) + STACK_FRAME_MIN_SIZE + 16)
-#define STACK_SWITCH_FRAME_REGS (STACK_FRAME_MIN_SIZE + 16)
+#define STACK_USER_INT_FRAME_SIZE (sizeof(struct pt_regs) + STACK_FRAME_MIN_SIZE)
+#define STACK_INT_FRAME_REGS STACK_FRAME_MIN_SIZE
+#define STACK_INT_FRAME_MARKER 12 /* Reserved word next to CR save word */
+
+/*
+ * The switch frame has to match the format of the int frames up to pt_regs,
+ * because fields are accessed with the int frame pt_regs offsets.
+ */
+#define STACK_SWITCH_FRAME_SIZE (sizeof(struct pt_regs) + STACK_FRAME_MIN_SIZE)
+#define STACK_SWITCH_FRAME_REGS STACK_FRAME_MIN_SIZE
#else
/*
* The ELFv1 ABI specifies 48 bytes plus a minimum 64 byte parameter save
--
2.37.2
prev parent reply other threads:[~2022-10-31 6:13 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-31 5:54 [RFC PATCH 00/19] Remove STACK_FRAME_OVERHEAD Nicholas Piggin
2022-10-31 5:54 ` [RFC PATCH 01/19] powerpc/perf: callchain validate kernel stack pointer bounds Nicholas Piggin
2022-11-04 13:10 ` Segher Boessenkool
2022-10-31 5:54 ` [RFC PATCH 02/19] powerpc: Rearrange copy_thread child stack creation Nicholas Piggin
2022-10-31 5:54 ` [RFC PATCH 03/19] powerpc/64: Remove asm interrupt tracing call helpers Nicholas Piggin
2022-10-31 5:54 ` [RFC PATCH 04/19] powerpc/pseries: hvcall stack frame overhead Nicholas Piggin
2022-10-31 5:54 ` [RFC PATCH 05/19] powerpc/32: Use load and store multiple in GPR save/restore macros Nicholas Piggin
2022-11-03 8:26 ` Christophe Leroy
2022-11-07 12:45 ` Nicholas Piggin
2022-11-07 12:51 ` Christophe Leroy
2022-10-31 5:54 ` [RFC PATCH 06/19] powerpc: simplify ppc_save_regs Nicholas Piggin
2022-10-31 5:54 ` [RFC PATCH 07/19] powerpc: add definition for pt_regs offset within an interrupt frame Nicholas Piggin
2022-10-31 5:54 ` [RFC PATCH 08/19] powerpc: add a definition for the marker offset within the " Nicholas Piggin
2022-10-31 5:54 ` [RFC PATCH 09/19] powerpc: Rename STACK_FRAME_MARKER and derive it from frame offset Nicholas Piggin
2022-10-31 5:54 ` [RFC PATCH 10/19] powerpc: add a define for the user interrupt frame size Nicholas Piggin
2022-10-31 5:54 ` [RFC PATCH 11/19] powerpc: add a define for the switch frame size and regs offset Nicholas Piggin
2022-10-31 5:54 ` [RFC PATCH 12/19] powerpc: copy_thread fill in interrupt frame marker and back chain Nicholas Piggin
2022-10-31 5:54 ` [RFC PATCH 13/19] powerpc: copy_thread add a back chain to the switch stack frame Nicholas Piggin
2022-10-31 5:54 ` [RFC PATCH 14/19] powerpc: split validate_sp into two functions Nicholas Piggin
2022-11-07 0:58 ` Russell Currey
2022-11-07 12:29 ` Nicholas Piggin
2022-10-31 5:54 ` [RFC PATCH 15/19] powerpc: allow minimum sized kernel stack frames Nicholas Piggin
2022-10-31 5:54 ` [RFC PATCH 16/19] powerpc/64: ELFv2 use minimal stack frames in int and switch frame sizes Nicholas Piggin
2022-10-31 5:54 ` [RFC PATCH 17/19] powerpc: remove STACK_FRAME_OVERHEAD Nicholas Piggin
2022-10-31 5:54 ` [RFC PATCH 18/19] powerpc: change stack marker memory operations to 32-bit Nicholas Piggin
2022-10-31 5:54 ` Nicholas Piggin [this message]
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