From: Peter Zijlstra <peterz@infradead.org>
To: x86@kernel.org
Cc: linux-kernel@vger.kernel.org, peterz@infradead.org,
jpoimboe@redhat.com, mark.rutland@arm.com, dvyukov@google.com,
seanjc@google.com, pbonzini@redhat.com, mbenes@suse.cz
Subject: [PATCH 06/22] x86,entry_32: Remove .fixup usage
Date: Fri, 05 Nov 2021 18:10:29 +0100 [thread overview]
Message-ID: <20211105171820.809028458@infradead.org> (raw)
In-Reply-To: 20211105171023.989862879@infradead.org
Where possible, push the .fixup into code, at the tail of functions.
This is hard for macros since they're used in multiple functions,
therefore introduce a new extable handler for pop-segment.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
arch/x86/entry/entry_32.S | 28 ++++++++--------------------
arch/x86/include/asm/extable_fixup_types.h | 2 ++
arch/x86/mm/extable.c | 14 ++++++++++++++
3 files changed, 24 insertions(+), 20 deletions(-)
--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -270,17 +270,9 @@
3: popl %fs
addl $(4 + \pop), %esp /* pop the unused "gs" slot */
IRET_FRAME
-.pushsection .fixup, "ax"
-4: movl $0, (%esp)
- jmp 1b
-5: movl $0, (%esp)
- jmp 2b
-6: movl $0, (%esp)
- jmp 3b
-.popsection
- _ASM_EXTABLE(1b, 4b)
- _ASM_EXTABLE(2b, 5b)
- _ASM_EXTABLE(3b, 6b)
+ _ASM_EXTABLE_TYPE(1b, 1b, EX_TYPE_POP_ZERO)
+ _ASM_EXTABLE_TYPE(2b, 2b, EX_TYPE_POP_ZERO)
+ _ASM_EXTABLE_TYPE(3b, 3b, EX_TYPE_POP_ZERO)
.endm
.macro RESTORE_ALL_NMI cr3_reg:req pop=0
@@ -925,10 +917,8 @@ SYM_FUNC_START(entry_SYSENTER_32)
sti
sysexit
-.pushsection .fixup, "ax"
-2: movl $0, PT_FS(%esp)
- jmp 1b
-.popsection
+2: movl $0, PT_FS(%esp)
+ jmp 1b
_ASM_EXTABLE(1b, 2b)
.Lsysenter_fix_flags:
@@ -996,8 +986,7 @@ SYM_FUNC_START(entry_INT80_32)
*/
iret
-.section .fixup, "ax"
-SYM_CODE_START(asm_iret_error)
+.Lasm_iret_error:
pushl $0 # no error code
pushl $iret_error
@@ -1014,9 +1003,8 @@ SYM_CODE_START(asm_iret_error)
#endif
jmp handle_exception
-SYM_CODE_END(asm_iret_error)
-.previous
- _ASM_EXTABLE(.Lirq_return, asm_iret_error)
+
+ _ASM_EXTABLE(.Lirq_return, .Lasm_iret_error)
SYM_FUNC_END(entry_INT80_32)
.macro FIXUP_ESPFIX_STACK
--- a/arch/x86/include/asm/extable_fixup_types.h
+++ b/arch/x86/include/asm/extable_fixup_types.h
@@ -19,4 +19,6 @@
#define EX_TYPE_DEFAULT_MCE_SAFE 12
#define EX_TYPE_FAULT_MCE_SAFE 13
+#define EX_TYPE_POP_ZERO 14
+
#endif
--- a/arch/x86/mm/extable.c
+++ b/arch/x86/mm/extable.c
@@ -99,6 +99,18 @@ static bool ex_handler_clear_fs(const st
return ex_handler_default(fixup, regs);
}
+static bool ex_handler_pop_zero(const struct exception_table_entry *fixup,
+ struct pt_regs *regs)
+{
+ /*
+ * Typically used for when "pop %seg" traps, in which case we'll clear
+ * the stack slot and re-try the instruction, which will then succeed
+ * to pop zero.
+ */
+ *((unsigned long *)regs->sp) = 0;
+ return ex_handler_default(fixup, regs);
+}
+
int ex_get_fixup_type(unsigned long ip)
{
const struct exception_table_entry *e = search_exception_tables(ip);
@@ -156,6 +168,8 @@ int fixup_exception(struct pt_regs *regs
case EX_TYPE_WRMSR_IN_MCE:
ex_handler_msr_mce(regs, true);
break;
+ case EX_TYPE_POP_ZERO:
+ return ex_handler_pop_zero(e, regs);
}
BUG();
}
next prev parent reply other threads:[~2021-11-05 17:20 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-05 17:10 [PATCH 00/22] x86: Remove anonymous out-of-line fixups Peter Zijlstra
2021-11-05 17:10 ` [PATCH 01/22] bitfield.h: Fix "type of reg too small for mask" test Peter Zijlstra
2021-11-05 17:10 ` [PATCH 02/22] x86,mmx_32: Remove .fixup usage Peter Zijlstra
2021-11-05 17:10 ` [PATCH 03/22] x86,copy_user_64: " Peter Zijlstra
2021-11-05 17:10 ` [PATCH 04/22] x86,copy_mc_64: " Peter Zijlstra
2021-11-05 17:10 ` [PATCH 05/22] x86,entry_64: " Peter Zijlstra
2021-11-05 17:10 ` Peter Zijlstra [this message]
2021-11-05 17:10 ` [PATCH 07/22] x86,extable: Extend extable functionality Peter Zijlstra
2021-11-05 17:10 ` [PATCH 08/22] x86,msr: Remove .fixup usage Peter Zijlstra
2021-11-05 17:10 ` [PATCH 09/22] x86,futex: " Peter Zijlstra
2021-11-05 17:10 ` [PATCH 10/22] x86,uaccess: " Peter Zijlstra
2021-11-05 17:10 ` [PATCH 11/22] x86,xen: " Peter Zijlstra
2021-11-05 17:10 ` [PATCH 12/22] x86,fpu: " Peter Zijlstra
2021-11-05 17:10 ` [PATCH 13/22] x86,segment: " Peter Zijlstra
2021-11-05 17:10 ` [PATCH 14/22] x86,vmx: " Peter Zijlstra
2021-11-05 17:10 ` [PATCH 15/22] x86,checksum_32: " Peter Zijlstra
2021-11-05 17:10 ` [PATCH 16/22] x86,sgx: " Peter Zijlstra
2021-11-05 17:10 ` [PATCH 17/22] x86,kvm: " Peter Zijlstra
2021-11-05 17:10 ` [PATCH 18/22] x86,usercopy_32: Simplify __copy_user_intel_nocache() Peter Zijlstra
2021-11-05 17:10 ` [PATCH 19/22] x86,usercopy: Remove .fixup usage Peter Zijlstra
2021-11-05 17:10 ` [PATCH 20/22] x86,word-at-a-time: " Peter Zijlstra
2021-11-05 18:01 ` Josh Poimboeuf
2021-11-05 18:07 ` Peter Zijlstra
2021-11-08 16:47 ` Josh Poimboeuf
2021-11-08 18:29 ` Peter Zijlstra
2021-11-08 18:53 ` Nick Desaulniers
2021-11-09 8:23 ` Peter Zijlstra
2021-11-09 19:22 ` Nick Desaulniers
2021-11-09 20:59 ` Bill Wendling
2021-11-09 21:21 ` Peter Zijlstra
2021-11-09 21:25 ` Nick Desaulniers
2021-11-09 22:11 ` Peter Zijlstra
2021-11-09 22:15 ` Nick Desaulniers
2021-11-09 21:07 ` Peter Zijlstra
2021-11-10 10:18 ` Peter Zijlstra
2021-11-10 10:46 ` David Laight
2021-11-10 11:09 ` Peter Zijlstra
2021-11-10 12:20 ` David Laight
2021-11-12 1:50 ` Josh Poimboeuf
2021-11-12 9:33 ` Peter Zijlstra
2021-11-13 5:35 ` Josh Poimboeuf
2021-11-15 12:36 ` Miroslav Benes
2021-11-15 13:01 ` Joe Lawrence
2021-11-15 23:40 ` Josh Poimboeuf
2021-11-16 7:25 ` Miroslav Benes
2021-11-15 12:59 ` Miroslav Benes
2021-11-16 21:27 ` Josh Poimboeuf
2021-11-18 7:15 ` Miroslav Benes
2021-11-22 17:46 ` Petr Mladek
2021-11-24 17:42 ` Josh Poimboeuf
2021-11-25 8:18 ` Petr Mladek
2021-11-10 12:14 ` Segher Boessenkool
2021-11-05 17:10 ` [PATCH 21/22] x86: Remove .fixup section Peter Zijlstra
2021-11-05 17:10 ` [PATCH 22/22] objtool: Remove .fixup handling Peter Zijlstra
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