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Message-ID: <20220419205241.339242797@infradead.org>
User-Agent: quilt/0.66
Date:   Tue, 19 Apr 2022 22:41:11 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     x86@kernel.org, jpoimboe@redhat.com, brgerst@gmail.com,
        jiangshanlai@gmail.com, Andrew.Cooper3@citrix.com
Cc:     linux-kernel@vger.kernel.org, peterz@infradead.org
Subject: [PATCH 2/2] x86,entry: Use PUSH_AND_CLEAR_REGS for compat
References: <20220419204109.520779286@infradead.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Precedence: bulk

Since the upper regs don't exist for ia32 code, preserving them
doesn't hurt and it simplifies the code.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 arch/x86/entry/calling.h         |    9 ++--
 arch/x86/entry/entry_64_compat.S |   87 +--------------------------------------
 2 files changed, 8 insertions(+), 88 deletions(-)

--- a/arch/x86/entry/calling.h
+++ b/arch/x86/entry/calling.h
@@ -63,13 +63,15 @@ For 32-bit we have the following convent
  * for assembly code:
  */
 
-.macro PUSH_REGS rdx=%rdx rax=%rax save_ret=0
+.macro PUSH_REGS rdx=%rdx rax=%rax save_ret=0 save_rdi=1
 	.if \save_ret
 	pushq	%rsi		/* pt_regs->si */
 	movq	8(%rsp), %rsi	/* temporarily store the return address in %rsi */
 	movq	%rdi, 8(%rsp)	/* pt_regs->di (overwriting original return address) */
 	.else
+	.if \save_rdi
 	pushq   %rdi		/* pt_regs->di */
+	.endif
 	pushq   %rsi		/* pt_regs->si */
 	.endif
 	pushq	\rdx		/* pt_regs->dx */
@@ -111,11 +113,10 @@ For 32-bit we have the following convent
 	xorl	%r13d, %r13d	/* nospec r13 */
 	xorl	%r14d, %r14d	/* nospec r14 */
 	xorl	%r15d, %r15d	/* nospec r15 */
-
 .endm
 
-.macro PUSH_AND_CLEAR_REGS rdx=%rdx rax=%rax save_ret=0
-	PUSH_REGS rdx=\rdx, rax=\rax, save_ret=\save_ret
+.macro PUSH_AND_CLEAR_REGS rdx=%rdx rax=%rax save_ret=0 save_rdi=1
+	PUSH_REGS rdx=\rdx, rax=\rax, save_ret=\save_ret save_rdi=\save_rdi
 	CLEAR_REGS
 .endm
 
--- a/arch/x86/entry/entry_64_compat.S
+++ b/arch/x86/entry/entry_64_compat.S
@@ -83,32 +83,7 @@ SYM_INNER_LABEL(entry_SYSENTER_compat_af
 	movl	%eax, %eax
 
 	pushq	%rax			/* pt_regs->orig_ax */
-	pushq	%rdi			/* pt_regs->di */
-	pushq	%rsi			/* pt_regs->si */
-	pushq	%rdx			/* pt_regs->dx */
-	pushq	%rcx			/* pt_regs->cx */
-	pushq	$-ENOSYS		/* pt_regs->ax */
-	pushq   $0			/* pt_regs->r8  = 0 */
-	xorl	%r8d, %r8d		/* nospec   r8 */
-	pushq   $0			/* pt_regs->r9  = 0 */
-	xorl	%r9d, %r9d		/* nospec   r9 */
-	pushq   $0			/* pt_regs->r10 = 0 */
-	xorl	%r10d, %r10d		/* nospec   r10 */
-	pushq   $0			/* pt_regs->r11 = 0 */
-	xorl	%r11d, %r11d		/* nospec   r11 */
-	pushq   %rbx                    /* pt_regs->rbx */
-	xorl	%ebx, %ebx		/* nospec   rbx */
-	pushq   %rbp                    /* pt_regs->rbp (will be overwritten) */
-	xorl	%ebp, %ebp		/* nospec   rbp */
-	pushq   $0			/* pt_regs->r12 = 0 */
-	xorl	%r12d, %r12d		/* nospec   r12 */
-	pushq   $0			/* pt_regs->r13 = 0 */
-	xorl	%r13d, %r13d		/* nospec   r13 */
-	pushq   $0			/* pt_regs->r14 = 0 */
-	xorl	%r14d, %r14d		/* nospec   r14 */
-	pushq   $0			/* pt_regs->r15 = 0 */
-	xorl	%r15d, %r15d		/* nospec   r15 */
-
+	PUSH_AND_CLEAR_REGS rax=$-ENOSYS
 	UNWIND_HINT_REGS
 
 	cld
@@ -225,35 +200,7 @@ SYM_INNER_LABEL(entry_SYSCALL_compat_saf
 SYM_INNER_LABEL(entry_SYSCALL_compat_after_hwframe, SYM_L_GLOBAL)
 	movl	%eax, %eax		/* discard orig_ax high bits */
 	pushq	%rax			/* pt_regs->orig_ax */
-	pushq	%rdi			/* pt_regs->di */
-	pushq	%rsi			/* pt_regs->si */
-	xorl	%esi, %esi		/* nospec   si */
-	pushq	%rdx			/* pt_regs->dx */
-	xorl	%edx, %edx		/* nospec   dx */
-	pushq	%rbp			/* pt_regs->cx (stashed in bp) */
-	xorl	%ecx, %ecx		/* nospec   cx */
-	pushq	$-ENOSYS		/* pt_regs->ax */
-	pushq   $0			/* pt_regs->r8  = 0 */
-	xorl	%r8d, %r8d		/* nospec   r8 */
-	pushq   $0			/* pt_regs->r9  = 0 */
-	xorl	%r9d, %r9d		/* nospec   r9 */
-	pushq   $0			/* pt_regs->r10 = 0 */
-	xorl	%r10d, %r10d		/* nospec   r10 */
-	pushq   $0			/* pt_regs->r11 = 0 */
-	xorl	%r11d, %r11d		/* nospec   r11 */
-	pushq   %rbx                    /* pt_regs->rbx */
-	xorl	%ebx, %ebx		/* nospec   rbx */
-	pushq   %rbp                    /* pt_regs->rbp (will be overwritten) */
-	xorl	%ebp, %ebp		/* nospec   rbp */
-	pushq   $0			/* pt_regs->r12 = 0 */
-	xorl	%r12d, %r12d		/* nospec   r12 */
-	pushq   $0			/* pt_regs->r13 = 0 */
-	xorl	%r13d, %r13d		/* nospec   r13 */
-	pushq   $0			/* pt_regs->r14 = 0 */
-	xorl	%r14d, %r14d		/* nospec   r14 */
-	pushq   $0			/* pt_regs->r15 = 0 */
-	xorl	%r15d, %r15d		/* nospec   r15 */
-
+	PUSH_AND_CLEAR_REGS rax=$-ENOSYS
 	UNWIND_HINT_REGS
 
 	movq	%rsp, %rdi
@@ -381,35 +328,7 @@ SYM_CODE_START(entry_INT80_compat)
 	pushq	1*8(%rdi)		/* regs->orig_ax */
 	pushq	(%rdi)			/* pt_regs->di */
 .Lint80_keep_stack:
-
-	pushq	%rsi			/* pt_regs->si */
-	xorl	%esi, %esi		/* nospec   si */
-	pushq	%rdx			/* pt_regs->dx */
-	xorl	%edx, %edx		/* nospec   dx */
-	pushq	%rcx			/* pt_regs->cx */
-	xorl	%ecx, %ecx		/* nospec   cx */
-	pushq	$-ENOSYS		/* pt_regs->ax */
-	pushq   %r8			/* pt_regs->r8 */
-	xorl	%r8d, %r8d		/* nospec   r8 */
-	pushq   %r9			/* pt_regs->r9 */
-	xorl	%r9d, %r9d		/* nospec   r9 */
-	pushq   %r10			/* pt_regs->r10*/
-	xorl	%r10d, %r10d		/* nospec   r10 */
-	pushq   %r11			/* pt_regs->r11 */
-	xorl	%r11d, %r11d		/* nospec   r11 */
-	pushq   %rbx                    /* pt_regs->rbx */
-	xorl	%ebx, %ebx		/* nospec   rbx */
-	pushq   %rbp                    /* pt_regs->rbp */
-	xorl	%ebp, %ebp		/* nospec   rbp */
-	pushq   %r12                    /* pt_regs->r12 */
-	xorl	%r12d, %r12d		/* nospec   r12 */
-	pushq   %r13                    /* pt_regs->r13 */
-	xorl	%r13d, %r13d		/* nospec   r13 */
-	pushq   %r14                    /* pt_regs->r14 */
-	xorl	%r14d, %r14d		/* nospec   r14 */
-	pushq   %r15                    /* pt_regs->r15 */
-	xorl	%r15d, %r15d		/* nospec   r15 */
-
+	PUSH_AND_CLEAR_REGS save_rdi=0
 	UNWIND_HINT_REGS
 
 	cld