linux-kernel - [PATCH 5.15 212/279] Revert "parisc: Reduce sigreturn trampoline to 3 instructions"

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Date:   Wed, 24 Nov 2021 12:58:19 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Helge Deller <deller@....de>
Subject: [PATCH 5.15 212/279] Revert "parisc: Reduce sigreturn trampoline to 3 instructions"

From: Helge Deller <deller@....de>

commit 79df39d535c7a3770856fe9f5aba8c0ad1eebdb6 upstream.

This reverts commit e4f2006f1287e7ea17660490569cff323772dac4.

This patch shows problems with signal handling. Revert it for now.

Signed-off-by: Helge Deller <deller@....de>
Cc: <stable@...r.kernel.org> # v5.15
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/parisc/include/asm/rt_sigframe.h |    2 +-
 arch/parisc/kernel/signal.c           |   13 +++++++------
 arch/parisc/kernel/signal32.h         |    2 +-
 3 files changed, 9 insertions(+), 8 deletions(-)

--- a/arch/parisc/include/asm/rt_sigframe.h
+++ b/arch/parisc/include/asm/rt_sigframe.h
@@ -2,7 +2,7 @@
 #ifndef _ASM_PARISC_RT_SIGFRAME_H
 #define _ASM_PARISC_RT_SIGFRAME_H
 
-#define SIGRETURN_TRAMP 3
+#define SIGRETURN_TRAMP 4
 #define SIGRESTARTBLOCK_TRAMP 5 
 #define TRAMP_SIZE (SIGRETURN_TRAMP + SIGRESTARTBLOCK_TRAMP)
 
--- a/arch/parisc/kernel/signal.c
+++ b/arch/parisc/kernel/signal.c
@@ -288,21 +288,22 @@ setup_rt_frame(struct ksignal *ksig, sig
 	   already in userspace. The first words of tramp are used to
 	   save the previous sigrestartblock trampoline that might be
 	   on the stack. We start the sigreturn trampoline at 
-	   SIGRESTARTBLOCK_TRAMP. */
+	   SIGRESTARTBLOCK_TRAMP+X. */
 	err |= __put_user(in_syscall ? INSN_LDI_R25_1 : INSN_LDI_R25_0,
 			&frame->tramp[SIGRESTARTBLOCK_TRAMP+0]);
-	err |= __put_user(INSN_BLE_SR2_R0, 
+	err |= __put_user(INSN_LDI_R20,
 			&frame->tramp[SIGRESTARTBLOCK_TRAMP+1]);
-	err |= __put_user(INSN_LDI_R20,
+	err |= __put_user(INSN_BLE_SR2_R0,
 			&frame->tramp[SIGRESTARTBLOCK_TRAMP+2]);
+	err |= __put_user(INSN_NOP, &frame->tramp[SIGRESTARTBLOCK_TRAMP+3]);
 
-	start = (unsigned long) &frame->tramp[SIGRESTARTBLOCK_TRAMP+0];
-	end = (unsigned long) &frame->tramp[SIGRESTARTBLOCK_TRAMP+3];
+	start = (unsigned long) &frame->tramp[0];
+	end = (unsigned long) &frame->tramp[TRAMP_SIZE];
 	flush_user_dcache_range_asm(start, end);
 	flush_user_icache_range_asm(start, end);
 
 	/* TRAMP Words 0-4, Length 5 = SIGRESTARTBLOCK_TRAMP
-	 * TRAMP Words 5-7, Length 3 = SIGRETURN_TRAMP
+	 * TRAMP Words 5-9, Length 4 = SIGRETURN_TRAMP
 	 * So the SIGRETURN_TRAMP is at the end of SIGRESTARTBLOCK_TRAMP
 	 */
 	rp = (unsigned long) &frame->tramp[SIGRESTARTBLOCK_TRAMP];
--- a/arch/parisc/kernel/signal32.h
+++ b/arch/parisc/kernel/signal32.h
@@ -36,7 +36,7 @@ struct compat_regfile {
         compat_int_t rf_sar;
 };
 
-#define COMPAT_SIGRETURN_TRAMP 3
+#define COMPAT_SIGRETURN_TRAMP 4
 #define COMPAT_SIGRESTARTBLOCK_TRAMP 5
 #define COMPAT_TRAMP_SIZE (COMPAT_SIGRETURN_TRAMP + \
 				COMPAT_SIGRESTARTBLOCK_TRAMP)