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| author |   Peter Zijlstra <peterz@infradead.org> | 2021-11-10 11:01:08 +0100 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2021-12-11 09:09:46 +0100 |
| commit | aa93e2ad7464ffb90155a5ffdde963816f86d5dc (patch) | |
| tree | 345b322a089c1ca16e708ed1123555d729c5bc82 | |
| parent | x86/entry_64: Remove .fixup usage (diff) | |
| download | linux-dev-aa93e2ad7464ffb90155a5ffdde963816f86d5dc.tar.xz linux-dev-aa93e2ad7464ffb90155a5ffdde963816f86d5dc.zip | |
x86/entry_32: Remove .fixup usage
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 to pop zeros.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20211110101325.245184699@infradead.org
| -rw-r--r-- | arch/x86/entry/entry_32.S | 28 | ||||
| -rw-r--r-- | arch/x86/include/asm/extable_fixup_types.h | 2 | ||||
| -rw-r--r-- | arch/x86/mm/extable.c | 14 |
3 files changed, 24 insertions, 20 deletions
diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S index 00413e37feee..e0a95d8a6553 100644 --- 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 @@ restore_all_switch_stack: */ 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 diff --git a/arch/x86/include/asm/extable_fixup_types.h b/arch/x86/include/asm/extable_fixup_types.h index 409524d5d2eb..4d709a2768bb 100644 --- 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 diff --git a/arch/x86/mm/extable.c b/arch/x86/mm/extable.c index 5cd2a88930a9..fb0c4752df1a 100644 --- a/arch/x86/mm/extable.c +++ b/arch/x86/mm/extable.c @@ -99,6 +99,18 @@ static bool ex_handler_clear_fs(const struct exception_table_entry *fixup, 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, int trapnr, unsigned long error_code, 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(); } |