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Message-ID: <5b8d0dee-8fb6-45af-ba6c-7f74aff9a4b8@stanley.mountain>
Date: Wed, 4 Dec 2024 10:24:41 +0300
From: Dan Carpenter <dan.carpenter@...aro.org>
To: Uros Bizjak <ubizjak@...il.com>
Cc: x86@...nel.org, linux-sparse@...r.kernel.org, linux-mm@...ck.org,
linux-kernel@...r.kernel.org, linux-bcachefs@...r.kernel.org,
linux-arch@...r.kernel.org, netdev@...r.kernel.org,
Thomas Gleixner <tglx@...utronix.de>,
Dennis Zhou <dennis@...nel.org>, Tejun Heo <tj@...nel.org>,
Christoph Lameter <cl@...ux.com>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Andy Lutomirski <luto@...nel.org>, Ingo Molnar <mingo@...nel.org>,
Luc Van Oostenryck <luc.vanoostenryck@...il.com>,
Nadav Amit <nadav.amit@...il.com>, Brian Gerst <brgerst@...il.com>,
"H . Peter Anvin" <hpa@...or.com>,
Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH 0/6] Enable strict percpu address space checks
On Tue, Nov 26, 2024 at 06:21:17PM +0100, Uros Bizjak wrote:
> This patchset enables strict percpu address space checks via x86 named
> address space qualifiers. Percpu variables are declared in
> __seg_gs/__seg_fs named AS and kept named AS qualified until they
> are dereferenced via percpu accessor. This approach enables various
> compiler checks for cross-namespace variable assignments.
>
> Please note that current version of sparse doesn't know anything about
> __typeof_unqual__() operator. Avoid the usage of __typeof_unqual__()
> when sparse checking is active to prevent sparse errors with unknowing
> keyword.
I don't think it would be super hard to add support to Sparse. The only places
where typeof and typeof_unqual are different is that you have to mask away the
qualifiers in examine_typeof()?
I would take over Sparse maintainership but I'm far too sloppy to do it. We
should get Greg to take over, he likes abandoned projects. ;)
Signed-off-by: Dan Carpenter <dan.carpenter@...aro.org>
---
ast-inspect.c | 1 +
ctags.c | 1 +
dissect.c | 1 +
evaluate.c | 3 ++-
parse.c | 24 +++++++++++++++++++++---
show-parse.c | 1 +
symbol.c | 17 ++++++++++++++++-
symbol.h | 1 +
8 files changed, 44 insertions(+), 5 deletions(-)
diff --git a/ast-inspect.c b/ast-inspect.c
index b510cd9b1d2c..e940a93a411e 100644
--- a/ast-inspect.c
+++ b/ast-inspect.c
@@ -110,6 +110,7 @@ static const char *symbol_type_name(enum type type)
[SYM_UNION] = "SYM_UNION",
[SYM_ENUM] = "SYM_ENUM",
[SYM_TYPEOF] = "SYM_TYPEOF",
+ [SYM_TYPEOF_UNQUAL] = "SYM_TYPEOF_UNQUAL",
[SYM_BITFIELD] = "SYM_BITFIELD",
[SYM_LABEL] = "SYM_LABEL",
[SYM_RESTRICT] = "SYM_RESTRICT",
diff --git a/ctags.c b/ctags.c
index aa5f9718d847..afdc42b77b98 100644
--- a/ctags.c
+++ b/ctags.c
@@ -151,6 +151,7 @@ static void examine_symbol(struct symbol *sym)
sym->kind = 'e';
case SYM_PTR:
case SYM_TYPEOF:
+ case SYM_TYPEOF_UNQUAL:
case SYM_BITFIELD:
case SYM_FN:
case SYM_ARRAY:
diff --git a/dissect.c b/dissect.c
index 300d5ca99c97..9419c5931fbb 100644
--- a/dissect.c
+++ b/dissect.c
@@ -212,6 +212,7 @@ static void examine_sym_node(struct symbol *node, struct symbol *parent)
while ((base = node->ctype.base_type) != NULL)
switch (base->type) {
case SYM_TYPEOF:
+ case SYM_TYPEOF_UNQUAL:
node->ctype.base_type =
do_expression(U_VOID, base->initializer);
break;
diff --git a/evaluate.c b/evaluate.c
index fe716f631987..85a6447ba3ce 100644
--- a/evaluate.c
+++ b/evaluate.c
@@ -358,7 +358,8 @@ static inline int classify_type(struct symbol *type, struct symbol **base)
};
if (type->type == SYM_NODE)
type = type->ctype.base_type;
- if (type->type == SYM_TYPEOF) {
+ if (type->type == SYM_TYPEOF ||
+ type->type == SYM_TYPEOF_UNQUAL) {
type = examine_symbol_type(type);
if (type->type == SYM_NODE)
type = type->ctype.base_type;
diff --git a/parse.c b/parse.c
index f868bf63a0f5..95894bf5e54d 100644
--- a/parse.c
+++ b/parse.c
@@ -54,7 +54,7 @@ static struct token *handle_attributes(struct token *token, struct decl_state *c
typedef struct token *declarator_t(struct token *, struct symbol *, struct decl_state *);
static declarator_t
struct_specifier, union_specifier, enum_specifier,
- attribute_specifier, typeof_specifier,
+ attribute_specifier, typeof_specifier, typeof_unqual_specifier,
storage_specifier, thread_specifier;
static declarator_t generic_qualifier;
static declarator_t autotype_specifier;
@@ -196,6 +196,13 @@ static struct symbol_op typeof_op = {
.set = Set_S|Set_T,
};
+static struct symbol_op typeof_unqual_op = {
+ .type = KW_SPECIFIER,
+ .declarator = typeof_unqual_specifier,
+ .test = Set_Any,
+ .set = Set_S|Set_T,
+};
+
static struct symbol_op autotype_op = {
.type = KW_SPECIFIER,
.declarator = autotype_specifier,
@@ -480,6 +487,7 @@ static struct init_keyword {
/* Typedef ... */
N("typedef", &typedef_op, .mods = MOD_USERTYPE),
A("typeof", &typeof_op),
+ A("typeof_unqual", &typeof_unqual_op),
N("__auto_type", &autotype_op),
/* Type qualifiers */
@@ -1052,7 +1060,7 @@ static struct token *enum_specifier(struct token *token, struct symbol *sym, str
return ret;
}
-static struct token *typeof_specifier(struct token *token, struct symbol *sym, struct decl_state *ctx)
+static struct token *typeof_specifier_helper(struct token *token, struct symbol *sym, struct decl_state *ctx, bool qual)
{
if (!match_op(token, '(')) {
@@ -1065,7 +1073,7 @@ static struct token *typeof_specifier(struct token *token, struct symbol *sym, s
ctx->ctype.base_type = sym->ctype.base_type;
apply_ctype(token->pos, &ctx->ctype, &sym->ctype);
} else {
- struct symbol *typeof_sym = alloc_symbol(token->pos, SYM_TYPEOF);
+ struct symbol *typeof_sym = alloc_symbol(token->pos, qual? SYM_TYPEOF : SYM_TYPEOF_UNQUAL);
token = parse_expression(token->next, &typeof_sym->initializer);
typeof_sym->endpos = token->pos;
@@ -1078,6 +1086,16 @@ static struct token *typeof_specifier(struct token *token, struct symbol *sym, s
return expect(token, ')', "after typeof");
}
+static struct token *typeof_specifier(struct token *token, struct symbol *sym, struct decl_state *ctx)
+{
+ return typeof_specifier_helper(token, sym, ctx, true);
+}
+
+static struct token *typeof_unqual_specifier(struct token *token, struct symbol *sym, struct decl_state *ctx)
+{
+ return typeof_specifier_helper(token, sym, ctx, false);
+}
+
static struct token *autotype_specifier(struct token *token, struct symbol *sym, struct decl_state *ctx)
{
ctx->ctype.base_type = &autotype_ctype;
diff --git a/show-parse.c b/show-parse.c
index e2fc18bb4b3d..ceb6b3cb6f82 100644
--- a/show-parse.c
+++ b/show-parse.c
@@ -59,6 +59,7 @@ static void do_debug_symbol(struct symbol *sym, int indent)
[SYM_UNION] = "unin",
[SYM_ENUM] = "enum",
[SYM_TYPEOF] = "tpof",
+ [SYM_TYPEOF_UNQUAL] = "tpof_unqual",
[SYM_BITFIELD] = "bitf",
[SYM_LABEL] = "labl",
[SYM_RESTRICT] = "rstr",
diff --git a/symbol.c b/symbol.c
index 91352a3a447b..7060acb666d9 100644
--- a/symbol.c
+++ b/symbol.c
@@ -541,7 +541,7 @@ static struct symbol *examine_pointer_type(struct symbol *sym)
return sym;
}
-static struct symbol *examine_typeof(struct symbol *sym)
+static struct symbol *examine_typeof_helper(struct symbol *sym, bool qual)
{
struct symbol *base = evaluate_expression(sym->initializer);
unsigned long mod = 0;
@@ -550,6 +550,8 @@ static struct symbol *examine_typeof(struct symbol *sym)
base = &bad_ctype;
if (base->type == SYM_NODE) {
mod |= base->ctype.modifiers & MOD_TYPEOF;
+ if (!qual)
+ mod &= ~MOD_QUALIFIER;
base = base->ctype.base_type;
}
if (base->type == SYM_BITFIELD)
@@ -560,6 +562,16 @@ static struct symbol *examine_typeof(struct symbol *sym)
return examine_node_type(sym);
}
+static struct symbol *examine_typeof(struct symbol *sym)
+{
+ return examine_typeof_helper(sym, true);
+}
+
+static struct symbol *examine_typeof_unqual(struct symbol *sym)
+{
+ return examine_typeof_helper(sym, false);
+}
+
/*
* Fill in type size and alignment information for
* regular SYM_TYPE things.
@@ -595,6 +607,8 @@ struct symbol *examine_symbol_type(struct symbol * sym)
return sym;
case SYM_TYPEOF:
return examine_typeof(sym);
+ case SYM_TYPEOF_UNQUAL:
+ return examine_typeof_unqual(sym);
case SYM_PREPROCESSOR:
sparse_error(sym->pos, "ctype on preprocessor command? (%s)", show_ident(sym->ident));
return NULL;
@@ -628,6 +642,7 @@ const char* get_type_name(enum type type)
[SYM_UNION] = "union",
[SYM_ENUM] = "enum",
[SYM_TYPEOF] = "typeof",
+ [SYM_TYPEOF_UNQUAL] = "typeof_unqual",
[SYM_BITFIELD] = "bitfield",
[SYM_LABEL] = "label",
[SYM_RESTRICT] = "restrict",
diff --git a/symbol.h b/symbol.h
index 88130c15d4bd..3552d4391621 100644
--- a/symbol.h
+++ b/symbol.h
@@ -65,6 +65,7 @@ enum type {
SYM_UNION,
SYM_ENUM,
SYM_TYPEOF,
+ SYM_TYPEOF_UNQUAL,
SYM_BITFIELD,
SYM_LABEL,
SYM_RESTRICT,
--
2.45.2
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