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uaccess: add force_uaccess_{begin,end} helpers

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Add helpers to wrap the get_fs/set_fs magic for undoing any damange done
by set_fs(KERNEL_DS).  There is no real functional benefit, but this
documents the intent of these calls better, and will allow stubbing the
functions out easily for kernels builds that do not allow address space
overrides in the future.

[hch@lst.de: drop two incorrect hunks, fix a commit log typo]
  Link: http://lkml.kernel.org/r/20200714105505.935079-6-hch@lst.de

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Greentime Hu <green.hu@gmail.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Nick Hu <nickhu@andestech.com>
Cc: Vincent Chen <deanbo422@gmail.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Link: http://lkml.kernel.org/r/20200710135706.537715-6-hch@lst.de
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Christoph Hellwig
2020-08-11 18:33:47 -07:00
committed by Linus Torvalds
parent 428e2976a5
commit 3d13f313ce
12 changed files with 63 additions and 56 deletions
Download Patch File Download Diff File Expand all files Collapse all files

27
arch/mips/kernel/unaligned.c
View File

@@ -191,17 +191,16 @@ static void emulate_load_store_insn(struct pt_regs *regs,
* memory, so we need to "switch" the address limit to
* user space, so that address check can work properly.
*/
seg = get_fs();
set_fs(USER_DS);
seg = force_uaccess_begin();
switch (insn.spec3_format.func) {
case lhe_op:
if (!access_ok(addr, 2)) {
set_fs(seg);
force_uaccess_end(seg);
goto sigbus;
}
LoadHWE(addr, value, res);
if (res) {
set_fs(seg);
force_uaccess_end(seg);
goto fault;
}
compute_return_epc(regs);
@@ -209,12 +208,12 @@ static void emulate_load_store_insn(struct pt_regs *regs,
break;
case lwe_op:
if (!access_ok(addr, 4)) {
set_fs(seg);
force_uaccess_end(seg);
goto sigbus;
}
LoadWE(addr, value, res);
if (res) {
set_fs(seg);
force_uaccess_end(seg);
goto fault;
}
compute_return_epc(regs);
@@ -222,12 +221,12 @@ static void emulate_load_store_insn(struct pt_regs *regs,
break;
case lhue_op:
if (!access_ok(addr, 2)) {
set_fs(seg);
force_uaccess_end(seg);
goto sigbus;
}
LoadHWUE(addr, value, res);
if (res) {
set_fs(seg);
force_uaccess_end(seg);
goto fault;
}
compute_return_epc(regs);
@@ -235,35 +234,35 @@ static void emulate_load_store_insn(struct pt_regs *regs,
break;
case she_op:
if (!access_ok(addr, 2)) {
set_fs(seg);
force_uaccess_end(seg);
goto sigbus;
}
compute_return_epc(regs);
value = regs->regs[insn.spec3_format.rt];
StoreHWE(addr, value, res);
if (res) {
set_fs(seg);
force_uaccess_end(seg);
goto fault;
}
break;
case swe_op:
if (!access_ok(addr, 4)) {
set_fs(seg);
force_uaccess_end(seg);
goto sigbus;
}
compute_return_epc(regs);
value = regs->regs[insn.spec3_format.rt];
StoreWE(addr, value, res);
if (res) {
set_fs(seg);
force_uaccess_end(seg);
goto fault;
}
break;
default:
set_fs(seg);
force_uaccess_end(seg);
goto sigill;
}
set_fs(seg);
force_uaccess_end(seg);
}
#endif
break;