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| author | Christoph Hellwig <hch@lst.de> | 2020-09-03 16:22:40 +0200 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2020-09-08 22:21:36 -0400 |
| commit | 47058bb54b57962b3958a936ddbc59355e4c5504 (patch) | |
| tree | b1399d96916177ef63b8a86bf30daceb35508959 /arch/x86/lib/putuser.S | |
| parent | a1d826d475aafe63775b910e86ccd1bcf1e5a6e1 (diff) | |
| download | linux-stable-47058bb54b57962b3958a936ddbc59355e4c5504.tar.gz linux-stable-47058bb54b57962b3958a936ddbc59355e4c5504.tar.bz2 linux-stable-47058bb54b57962b3958a936ddbc59355e4c5504.zip | |
x86: remove address space overrides using set_fs()
Stop providing the possibility to override the address space using
set_fs() now that there is no need for that any more. To properly
handle the TASK_SIZE_MAX checking for 4 vs 5-level page tables on
x86 a new alternative is introduced, which just like the one in
entry_64.S has to use the hardcoded virtual address bits to escape
the fact that TASK_SIZE_MAX isn't actually a constant when 5-level
page tables are enabled.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'arch/x86/lib/putuser.S')
| -rw-r--r-- | arch/x86/lib/putuser.S | 25 |
1 files changed, 13 insertions, 12 deletions
diff --git a/arch/x86/lib/putuser.S b/arch/x86/lib/putuser.S index 7c7c92db8497..358239d77dff 100644 --- a/arch/x86/lib/putuser.S +++ b/arch/x86/lib/putuser.S @@ -31,12 +31,19 @@ * as they get called from within inline assembly. */ -#define ENTER mov PER_CPU_VAR(current_task), %_ASM_BX +#ifdef CONFIG_X86_5LEVEL +#define LOAD_TASK_SIZE_MINUS_N(n) \ + ALTERNATIVE __stringify(mov $((1 << 47) - 4096 - (n)),%rbx), \ + __stringify(mov $((1 << 56) - 4096 - (n)),%rbx), X86_FEATURE_LA57 +#else +#define LOAD_TASK_SIZE_MINUS_N(n) \ + mov $(TASK_SIZE_MAX - (n)),%_ASM_BX +#endif .text SYM_FUNC_START(__put_user_1) - ENTER - cmp TASK_addr_limit(%_ASM_BX),%_ASM_CX + LOAD_TASK_SIZE_MINUS_N(0) + cmp %_ASM_BX,%_ASM_CX jae .Lbad_put_user ASM_STAC 1: movb %al,(%_ASM_CX) @@ -47,9 +54,7 @@ SYM_FUNC_END(__put_user_1) EXPORT_SYMBOL(__put_user_1) SYM_FUNC_START(__put_user_2) - ENTER - mov TASK_addr_limit(%_ASM_BX),%_ASM_BX - sub $1,%_ASM_BX + LOAD_TASK_SIZE_MINUS_N(1) cmp %_ASM_BX,%_ASM_CX jae .Lbad_put_user ASM_STAC @@ -61,9 +66,7 @@ SYM_FUNC_END(__put_user_2) EXPORT_SYMBOL(__put_user_2) SYM_FUNC_START(__put_user_4) - ENTER - mov TASK_addr_limit(%_ASM_BX),%_ASM_BX - sub $3,%_ASM_BX + LOAD_TASK_SIZE_MINUS_N(3) cmp %_ASM_BX,%_ASM_CX jae .Lbad_put_user ASM_STAC @@ -75,9 +78,7 @@ SYM_FUNC_END(__put_user_4) EXPORT_SYMBOL(__put_user_4) SYM_FUNC_START(__put_user_8) - ENTER - mov TASK_addr_limit(%_ASM_BX),%_ASM_BX - sub $7,%_ASM_BX + LOAD_TASK_SIZE_MINUS_N(7) cmp %_ASM_BX,%_ASM_CX jae .Lbad_put_user ASM_STAC |