* Re: Please put the gcc "asm goto" bug workaround into stable
2024-02-16 18:45 ` Greg Kroah-Hartman
@ 2024-02-16 19:14 ` Linus Torvalds
2024-02-17 13:32 ` Greg Kroah-Hartman
0 siblings, 1 reply; 4+ messages in thread
From: Linus Torvalds @ 2024-02-16 19:14 UTC (permalink / raw)
To: Greg Kroah-Hartman; +Cc: stable, Sean Christopherson
[-- Attachment #1: Type: text/plain, Size: 446 bytes --]
On Fri, 16 Feb 2024 at 10:45, Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> I gave up at 6.1.y and if anyone wants them there, I'll gladly
> take a working backport, but I'm not going to attempt it.
The attached *looks* correct for 6.1.y.
No warranties. Caveat emptor. Your mileage may vary. Objects in
mirror are closer than they appear. These patches are known to the
state of California to cause cancer.
Linus
[-- Attachment #2: 0001-work-around-gcc-bugs-with-asm-goto-with-outputs.patch --]
[-- Type: text/x-patch, Size: 28235 bytes --]
From e31799903acaa1a35f69f1bbc93d54b38dc8eb4e Mon Sep 17 00:00:00 2001
From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Fri, 9 Feb 2024 12:39:31 -0800
Subject: [PATCH] work around gcc bugs with 'asm goto' with outputs
[ Commit 4356e9f841f7fbb945521cef3577ba394c65f3fc upstream ]
We've had issues with gcc and 'asm goto' before, and we created a
'asm_volatile_goto()' macro for that in the past: see commits
3f0116c3238a ("compiler/gcc4: Add quirk for 'asm goto' miscompilation
bug") and a9f180345f53 ("compiler/gcc4: Make quirk for
asm_volatile_goto() unconditional").
Then, much later, we ended up removing the workaround in commit
43c249ea0b1e ("compiler-gcc.h: remove ancient workaround for gcc PR
58670") because we no longer supported building the kernel with the
affected gcc versions, but we left the macro uses around.
Now, Sean Christopherson reports a new version of a very similar
problem, which is fixed by re-applying that ancient workaround. But the
problem in question is limited to only the 'asm goto with outputs'
cases, so instead of re-introducing the old workaround as-is, let's
rename and limit the workaround to just that much less common case.
It looks like there are at least two separate issues that all hit in
this area:
(a) some versions of gcc don't mark the asm goto as 'volatile' when it
has outputs:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98619
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110420
which is easy to work around by just adding the 'volatile' by hand.
(b) Internal compiler errors:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110422
which are worked around by adding the extra empty 'asm' as a
barrier, as in the original workaround.
but the problem Sean sees may be a third thing since it involves bad
code generation (not an ICE) even with the manually added 'volatile'.
The same old workaround works for this case, even if this feels a
bit like voodoo programming and may only be hiding the issue.
Reported-and-tested-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/all/20240208220604.140859-1-seanjc@google.com/
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Uros Bizjak <ubizjak@gmail.com>
Cc: Jakub Jelinek <jakub@redhat.com>
Cc: Andrew Pinski <quic_apinski@quicinc.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
arch/arc/include/asm/jump_label.h | 4 ++--
arch/arm/include/asm/jump_label.h | 4 ++--
arch/arm64/include/asm/alternative-macros.h | 4 ++--
arch/arm64/include/asm/jump_label.h | 4 ++--
arch/csky/include/asm/jump_label.h | 4 ++--
arch/mips/include/asm/jump_label.h | 4 ++--
arch/parisc/include/asm/jump_label.h | 4 ++--
arch/powerpc/include/asm/bug.h | 2 +-
arch/powerpc/include/asm/jump_label.h | 4 ++--
arch/powerpc/include/asm/uaccess.h | 8 ++++----
arch/powerpc/kernel/irq_64.c | 2 +-
arch/riscv/include/asm/jump_label.h | 4 ++--
arch/s390/include/asm/jump_label.h | 4 ++--
arch/sparc/include/asm/jump_label.h | 4 ++--
arch/um/include/asm/cpufeature.h | 2 +-
arch/x86/include/asm/cpufeature.h | 2 +-
arch/x86/include/asm/jump_label.h | 6 +++---
arch/x86/include/asm/rmwcc.h | 2 +-
arch/x86/include/asm/uaccess.h | 10 +++++-----
arch/x86/include/asm/virtext.h | 12 ++++++------
arch/x86/kvm/svm/svm_ops.h | 6 +++---
arch/x86/kvm/vmx/vmx.c | 8 ++++----
arch/x86/kvm/vmx/vmx_ops.h | 6 +++---
arch/xtensa/include/asm/jump_label.h | 4 ++--
include/linux/compiler-gcc.h | 19 +++++++++++++++++++
include/linux/compiler_types.h | 4 ++--
net/netfilter/nft_set_pipapo_avx2.c | 2 +-
samples/bpf/asm_goto_workaround.h | 8 ++++----
tools/arch/x86/include/asm/rmwcc.h | 2 +-
tools/include/linux/compiler_types.h | 4 ++--
30 files changed, 86 insertions(+), 67 deletions(-)
diff --git a/arch/arc/include/asm/jump_label.h b/arch/arc/include/asm/jump_label.h
index 9d9618079739..a339223d9e05 100644
--- a/arch/arc/include/asm/jump_label.h
+++ b/arch/arc/include/asm/jump_label.h
@@ -31,7 +31,7 @@
static __always_inline bool arch_static_branch(struct static_key *key,
bool branch)
{
- asm_volatile_goto(".balign "__stringify(JUMP_LABEL_NOP_SIZE)" \n"
+ asm goto(".balign "__stringify(JUMP_LABEL_NOP_SIZE)" \n"
"1: \n"
"nop \n"
".pushsection __jump_table, \"aw\" \n"
@@ -47,7 +47,7 @@ static __always_inline bool arch_static_branch(struct static_key *key,
static __always_inline bool arch_static_branch_jump(struct static_key *key,
bool branch)
{
- asm_volatile_goto(".balign "__stringify(JUMP_LABEL_NOP_SIZE)" \n"
+ asm goto(".balign "__stringify(JUMP_LABEL_NOP_SIZE)" \n"
"1: \n"
"b %l[l_yes] \n"
".pushsection __jump_table, \"aw\" \n"
diff --git a/arch/arm/include/asm/jump_label.h b/arch/arm/include/asm/jump_label.h
index e12d7d096fc0..e4eb54f6cd9f 100644
--- a/arch/arm/include/asm/jump_label.h
+++ b/arch/arm/include/asm/jump_label.h
@@ -11,7 +11,7 @@
static __always_inline bool arch_static_branch(struct static_key *key, bool branch)
{
- asm_volatile_goto("1:\n\t"
+ asm goto("1:\n\t"
WASM(nop) "\n\t"
".pushsection __jump_table, \"aw\"\n\t"
".word 1b, %l[l_yes], %c0\n\t"
@@ -25,7 +25,7 @@ static __always_inline bool arch_static_branch(struct static_key *key, bool bran
static __always_inline bool arch_static_branch_jump(struct static_key *key, bool branch)
{
- asm_volatile_goto("1:\n\t"
+ asm goto("1:\n\t"
WASM(b) " %l[l_yes]\n\t"
".pushsection __jump_table, \"aw\"\n\t"
".word 1b, %l[l_yes], %c0\n\t"
diff --git a/arch/arm64/include/asm/alternative-macros.h b/arch/arm64/include/asm/alternative-macros.h
index 3622e9f4fb44..51738c56e96c 100644
--- a/arch/arm64/include/asm/alternative-macros.h
+++ b/arch/arm64/include/asm/alternative-macros.h
@@ -229,7 +229,7 @@ alternative_has_feature_likely(unsigned long feature)
compiletime_assert(feature < ARM64_NCAPS,
"feature must be < ARM64_NCAPS");
- asm_volatile_goto(
+ asm goto(
ALTERNATIVE_CB("b %l[l_no]", %[feature], alt_cb_patch_nops)
:
: [feature] "i" (feature)
@@ -247,7 +247,7 @@ alternative_has_feature_unlikely(unsigned long feature)
compiletime_assert(feature < ARM64_NCAPS,
"feature must be < ARM64_NCAPS");
- asm_volatile_goto(
+ asm goto(
ALTERNATIVE("nop", "b %l[l_yes]", %[feature])
:
: [feature] "i" (feature)
diff --git a/arch/arm64/include/asm/jump_label.h b/arch/arm64/include/asm/jump_label.h
index cea441b6aa5d..b5bd3c38a01b 100644
--- a/arch/arm64/include/asm/jump_label.h
+++ b/arch/arm64/include/asm/jump_label.h
@@ -18,7 +18,7 @@
static __always_inline bool arch_static_branch(struct static_key *key,
bool branch)
{
- asm_volatile_goto(
+ asm goto(
"1: nop \n\t"
" .pushsection __jump_table, \"aw\" \n\t"
" .align 3 \n\t"
@@ -35,7 +35,7 @@ static __always_inline bool arch_static_branch(struct static_key *key,
static __always_inline bool arch_static_branch_jump(struct static_key *key,
bool branch)
{
- asm_volatile_goto(
+ asm goto(
"1: b %l[l_yes] \n\t"
" .pushsection __jump_table, \"aw\" \n\t"
" .align 3 \n\t"
diff --git a/arch/csky/include/asm/jump_label.h b/arch/csky/include/asm/jump_label.h
index 98a3f4b168bd..ef2e37a10a0f 100644
--- a/arch/csky/include/asm/jump_label.h
+++ b/arch/csky/include/asm/jump_label.h
@@ -12,7 +12,7 @@
static __always_inline bool arch_static_branch(struct static_key *key,
bool branch)
{
- asm_volatile_goto(
+ asm goto(
"1: nop32 \n"
" .pushsection __jump_table, \"aw\" \n"
" .align 2 \n"
@@ -29,7 +29,7 @@ static __always_inline bool arch_static_branch(struct static_key *key,
static __always_inline bool arch_static_branch_jump(struct static_key *key,
bool branch)
{
- asm_volatile_goto(
+ asm goto(
"1: bsr32 %l[label] \n"
" .pushsection __jump_table, \"aw\" \n"
" .align 2 \n"
diff --git a/arch/mips/include/asm/jump_label.h b/arch/mips/include/asm/jump_label.h
index c5c6864e64bc..405c85173f2c 100644
--- a/arch/mips/include/asm/jump_label.h
+++ b/arch/mips/include/asm/jump_label.h
@@ -36,7 +36,7 @@
static __always_inline bool arch_static_branch(struct static_key *key, bool branch)
{
- asm_volatile_goto("1:\t" B_INSN " 2f\n\t"
+ asm goto("1:\t" B_INSN " 2f\n\t"
"2:\t.insn\n\t"
".pushsection __jump_table, \"aw\"\n\t"
WORD_INSN " 1b, %l[l_yes], %0\n\t"
@@ -50,7 +50,7 @@ static __always_inline bool arch_static_branch(struct static_key *key, bool bran
static __always_inline bool arch_static_branch_jump(struct static_key *key, bool branch)
{
- asm_volatile_goto("1:\t" J_INSN " %l[l_yes]\n\t"
+ asm goto("1:\t" J_INSN " %l[l_yes]\n\t"
".pushsection __jump_table, \"aw\"\n\t"
WORD_INSN " 1b, %l[l_yes], %0\n\t"
".popsection\n\t"
diff --git a/arch/parisc/include/asm/jump_label.h b/arch/parisc/include/asm/jump_label.h
index 94428798b6aa..317ebc5edc9f 100644
--- a/arch/parisc/include/asm/jump_label.h
+++ b/arch/parisc/include/asm/jump_label.h
@@ -12,7 +12,7 @@
static __always_inline bool arch_static_branch(struct static_key *key, bool branch)
{
- asm_volatile_goto("1:\n\t"
+ asm goto("1:\n\t"
"nop\n\t"
".pushsection __jump_table, \"aw\"\n\t"
".align %1\n\t"
@@ -29,7 +29,7 @@ static __always_inline bool arch_static_branch(struct static_key *key, bool bran
static __always_inline bool arch_static_branch_jump(struct static_key *key, bool branch)
{
- asm_volatile_goto("1:\n\t"
+ asm goto("1:\n\t"
"b,n %l[l_yes]\n\t"
".pushsection __jump_table, \"aw\"\n\t"
".align %1\n\t"
diff --git a/arch/powerpc/include/asm/bug.h b/arch/powerpc/include/asm/bug.h
index 61a4736355c2..20d5052e2292 100644
--- a/arch/powerpc/include/asm/bug.h
+++ b/arch/powerpc/include/asm/bug.h
@@ -74,7 +74,7 @@
##__VA_ARGS__)
#define WARN_ENTRY(insn, flags, label, ...) \
- asm_volatile_goto( \
+ asm goto( \
"1: " insn "\n" \
EX_TABLE(1b, %l[label]) \
_EMIT_BUG_ENTRY \
diff --git a/arch/powerpc/include/asm/jump_label.h b/arch/powerpc/include/asm/jump_label.h
index 93ce3ec25387..2f2a86ed2280 100644
--- a/arch/powerpc/include/asm/jump_label.h
+++ b/arch/powerpc/include/asm/jump_label.h
@@ -17,7 +17,7 @@
static __always_inline bool arch_static_branch(struct static_key *key, bool branch)
{
- asm_volatile_goto("1:\n\t"
+ asm goto("1:\n\t"
"nop # arch_static_branch\n\t"
".pushsection __jump_table, \"aw\"\n\t"
".long 1b - ., %l[l_yes] - .\n\t"
@@ -32,7 +32,7 @@ static __always_inline bool arch_static_branch(struct static_key *key, bool bran
static __always_inline bool arch_static_branch_jump(struct static_key *key, bool branch)
{
- asm_volatile_goto("1:\n\t"
+ asm goto("1:\n\t"
"b %l[l_yes] # arch_static_branch_jump\n\t"
".pushsection __jump_table, \"aw\"\n\t"
".long 1b - ., %l[l_yes] - .\n\t"
diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h
index 3ddc65c63a49..45d4c9cf3f3a 100644
--- a/arch/powerpc/include/asm/uaccess.h
+++ b/arch/powerpc/include/asm/uaccess.h
@@ -72,7 +72,7 @@ __pu_failed: \
* are no aliasing issues.
*/
#define __put_user_asm_goto(x, addr, label, op) \
- asm_volatile_goto( \
+ asm goto( \
"1: " op "%U1%X1 %0,%1 # put_user\n" \
EX_TABLE(1b, %l2) \
: \
@@ -85,7 +85,7 @@ __pu_failed: \
__put_user_asm_goto(x, ptr, label, "std")
#else /* __powerpc64__ */
#define __put_user_asm2_goto(x, addr, label) \
- asm_volatile_goto( \
+ asm goto( \
"1: stw%X1 %0, %1\n" \
"2: stw%X1 %L0, %L1\n" \
EX_TABLE(1b, %l2) \
@@ -132,7 +132,7 @@ do { \
#ifdef CONFIG_CC_HAS_ASM_GOTO_OUTPUT
#define __get_user_asm_goto(x, addr, label, op) \
- asm_volatile_goto( \
+ asm_goto_output( \
"1: "op"%U1%X1 %0, %1 # get_user\n" \
EX_TABLE(1b, %l2) \
: "=r" (x) \
@@ -145,7 +145,7 @@ do { \
__get_user_asm_goto(x, addr, label, "ld")
#else /* __powerpc64__ */
#define __get_user_asm2_goto(x, addr, label) \
- asm_volatile_goto( \
+ asm_goto_output( \
"1: lwz%X1 %0, %1\n" \
"2: lwz%X1 %L0, %L1\n" \
EX_TABLE(1b, %l2) \
diff --git a/arch/powerpc/kernel/irq_64.c b/arch/powerpc/kernel/irq_64.c
index 9dc0ad3c533a..5a6e44e4d36f 100644
--- a/arch/powerpc/kernel/irq_64.c
+++ b/arch/powerpc/kernel/irq_64.c
@@ -230,7 +230,7 @@ notrace void arch_local_irq_restore(unsigned long mask)
* This allows interrupts to be unmasked without hard disabling, and
* also without new hard interrupts coming in ahead of pending ones.
*/
- asm_volatile_goto(
+ asm goto(
"1: \n"
" lbz 9,%0(13) \n"
" cmpwi 9,0 \n"
diff --git a/arch/riscv/include/asm/jump_label.h b/arch/riscv/include/asm/jump_label.h
index 14a5ea8d8ef0..4a35d787c019 100644
--- a/arch/riscv/include/asm/jump_label.h
+++ b/arch/riscv/include/asm/jump_label.h
@@ -17,7 +17,7 @@
static __always_inline bool arch_static_branch(struct static_key * const key,
const bool branch)
{
- asm_volatile_goto(
+ asm goto(
" .align 2 \n\t"
" .option push \n\t"
" .option norelax \n\t"
@@ -39,7 +39,7 @@ static __always_inline bool arch_static_branch(struct static_key * const key,
static __always_inline bool arch_static_branch_jump(struct static_key * const key,
const bool branch)
{
- asm_volatile_goto(
+ asm goto(
" .align 2 \n\t"
" .option push \n\t"
" .option norelax \n\t"
diff --git a/arch/s390/include/asm/jump_label.h b/arch/s390/include/asm/jump_label.h
index 895f774bbcc5..bf78cf381dfc 100644
--- a/arch/s390/include/asm/jump_label.h
+++ b/arch/s390/include/asm/jump_label.h
@@ -25,7 +25,7 @@
*/
static __always_inline bool arch_static_branch(struct static_key *key, bool branch)
{
- asm_volatile_goto("0: brcl 0,%l[label]\n"
+ asm goto("0: brcl 0,%l[label]\n"
".pushsection __jump_table,\"aw\"\n"
".balign 8\n"
".long 0b-.,%l[label]-.\n"
@@ -39,7 +39,7 @@ static __always_inline bool arch_static_branch(struct static_key *key, bool bran
static __always_inline bool arch_static_branch_jump(struct static_key *key, bool branch)
{
- asm_volatile_goto("0: brcl 15,%l[label]\n"
+ asm goto("0: brcl 15,%l[label]\n"
".pushsection __jump_table,\"aw\"\n"
".balign 8\n"
".long 0b-.,%l[label]-.\n"
diff --git a/arch/sparc/include/asm/jump_label.h b/arch/sparc/include/asm/jump_label.h
index 94eb529dcb77..2718cbea826a 100644
--- a/arch/sparc/include/asm/jump_label.h
+++ b/arch/sparc/include/asm/jump_label.h
@@ -10,7 +10,7 @@
static __always_inline bool arch_static_branch(struct static_key *key, bool branch)
{
- asm_volatile_goto("1:\n\t"
+ asm goto("1:\n\t"
"nop\n\t"
"nop\n\t"
".pushsection __jump_table, \"aw\"\n\t"
@@ -26,7 +26,7 @@ static __always_inline bool arch_static_branch(struct static_key *key, bool bran
static __always_inline bool arch_static_branch_jump(struct static_key *key, bool branch)
{
- asm_volatile_goto("1:\n\t"
+ asm goto("1:\n\t"
"b %l[l_yes]\n\t"
"nop\n\t"
".pushsection __jump_table, \"aw\"\n\t"
diff --git a/arch/um/include/asm/cpufeature.h b/arch/um/include/asm/cpufeature.h
index 4b6d1b526bc1..66fe06db872f 100644
--- a/arch/um/include/asm/cpufeature.h
+++ b/arch/um/include/asm/cpufeature.h
@@ -75,7 +75,7 @@ extern void setup_clear_cpu_cap(unsigned int bit);
*/
static __always_inline bool _static_cpu_has(u16 bit)
{
- asm_volatile_goto("1: jmp 6f\n"
+ asm goto("1: jmp 6f\n"
"2:\n"
".skip -(((5f-4f) - (2b-1b)) > 0) * "
"((5f-4f) - (2b-1b)),0x90\n"
diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h
index ce0c8f7d3218..f835b328ba24 100644
--- a/arch/x86/include/asm/cpufeature.h
+++ b/arch/x86/include/asm/cpufeature.h
@@ -173,7 +173,7 @@ extern void clear_cpu_cap(struct cpuinfo_x86 *c, unsigned int bit);
*/
static __always_inline bool _static_cpu_has(u16 bit)
{
- asm_volatile_goto(
+ asm goto(
ALTERNATIVE_TERNARY("jmp 6f", %P[feature], "", "jmp %l[t_no]")
".pushsection .altinstr_aux,\"ax\"\n"
"6:\n"
diff --git a/arch/x86/include/asm/jump_label.h b/arch/x86/include/asm/jump_label.h
index 071572e23d3a..cbbef32517f0 100644
--- a/arch/x86/include/asm/jump_label.h
+++ b/arch/x86/include/asm/jump_label.h
@@ -24,7 +24,7 @@
static __always_inline bool arch_static_branch(struct static_key *key, bool branch)
{
- asm_volatile_goto("1:"
+ asm goto("1:"
"jmp %l[l_yes] # objtool NOPs this \n\t"
JUMP_TABLE_ENTRY
: : "i" (key), "i" (2 | branch) : : l_yes);
@@ -38,7 +38,7 @@ static __always_inline bool arch_static_branch(struct static_key *key, bool bran
static __always_inline bool arch_static_branch(struct static_key * const key, const bool branch)
{
- asm_volatile_goto("1:"
+ asm goto("1:"
".byte " __stringify(BYTES_NOP5) "\n\t"
JUMP_TABLE_ENTRY
: : "i" (key), "i" (branch) : : l_yes);
@@ -52,7 +52,7 @@ static __always_inline bool arch_static_branch(struct static_key * const key, co
static __always_inline bool arch_static_branch_jump(struct static_key * const key, const bool branch)
{
- asm_volatile_goto("1:"
+ asm goto("1:"
"jmp %l[l_yes]\n\t"
JUMP_TABLE_ENTRY
: : "i" (key), "i" (branch) : : l_yes);
diff --git a/arch/x86/include/asm/rmwcc.h b/arch/x86/include/asm/rmwcc.h
index 7fa611216417..1919ccf493cd 100644
--- a/arch/x86/include/asm/rmwcc.h
+++ b/arch/x86/include/asm/rmwcc.h
@@ -18,7 +18,7 @@
#define __GEN_RMWcc(fullop, _var, cc, clobbers, ...) \
({ \
bool c = false; \
- asm_volatile_goto (fullop "; j" #cc " %l[cc_label]" \
+ asm goto (fullop "; j" #cc " %l[cc_label]" \
: : [var] "m" (_var), ## __VA_ARGS__ \
: clobbers : cc_label); \
if (0) { \
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index 6ca0c661cb63..c638535eedd5 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -155,7 +155,7 @@ extern int __get_user_bad(void);
#ifdef CONFIG_X86_32
#define __put_user_goto_u64(x, addr, label) \
- asm_volatile_goto("\n" \
+ asm goto("\n" \
"1: movl %%eax,0(%1)\n" \
"2: movl %%edx,4(%1)\n" \
_ASM_EXTABLE_UA(1b, %l2) \
@@ -317,7 +317,7 @@ do { \
} while (0)
#define __get_user_asm(x, addr, itype, ltype, label) \
- asm_volatile_goto("\n" \
+ asm_goto_output("\n" \
"1: mov"itype" %[umem],%[output]\n" \
_ASM_EXTABLE_UA(1b, %l2) \
: [output] ltype(x) \
@@ -397,7 +397,7 @@ do { \
__typeof__(_ptr) _old = (__typeof__(_ptr))(_pold); \
__typeof__(*(_ptr)) __old = *_old; \
__typeof__(*(_ptr)) __new = (_new); \
- asm_volatile_goto("\n" \
+ asm_goto_output("\n" \
"1: " LOCK_PREFIX "cmpxchg"itype" %[new], %[ptr]\n"\
_ASM_EXTABLE_UA(1b, %l[label]) \
: CC_OUT(z) (success), \
@@ -416,7 +416,7 @@ do { \
__typeof__(_ptr) _old = (__typeof__(_ptr))(_pold); \
__typeof__(*(_ptr)) __old = *_old; \
__typeof__(*(_ptr)) __new = (_new); \
- asm_volatile_goto("\n" \
+ asm_goto_output("\n" \
"1: " LOCK_PREFIX "cmpxchg8b %[ptr]\n" \
_ASM_EXTABLE_UA(1b, %l[label]) \
: CC_OUT(z) (success), \
@@ -499,7 +499,7 @@ struct __large_struct { unsigned long buf[100]; };
* aliasing issues.
*/
#define __put_user_goto(x, addr, itype, ltype, label) \
- asm_volatile_goto("\n" \
+ asm goto("\n" \
"1: mov"itype" %0,%1\n" \
_ASM_EXTABLE_UA(1b, %l2) \
: : ltype(x), "m" (__m(addr)) \
diff --git a/arch/x86/include/asm/virtext.h b/arch/x86/include/asm/virtext.h
index 6c2e3ff3cb28..724ce44809ed 100644
--- a/arch/x86/include/asm/virtext.h
+++ b/arch/x86/include/asm/virtext.h
@@ -43,9 +43,9 @@ static inline int cpu_has_vmx(void)
*/
static inline int cpu_vmxoff(void)
{
- asm_volatile_goto("1: vmxoff\n\t"
- _ASM_EXTABLE(1b, %l[fault])
- ::: "cc", "memory" : fault);
+ asm goto("1: vmxoff\n\t"
+ _ASM_EXTABLE(1b, %l[fault])
+ ::: "cc", "memory" : fault);
cr4_clear_bits(X86_CR4_VMXE);
return 0;
@@ -129,9 +129,9 @@ static inline void cpu_svm_disable(void)
* case, GIF must already be set, otherwise the NMI would have
* been blocked, so just eat the fault.
*/
- asm_volatile_goto("1: stgi\n\t"
- _ASM_EXTABLE(1b, %l[fault])
- ::: "memory" : fault);
+ asm goto("1: stgi\n\t"
+ _ASM_EXTABLE(1b, %l[fault])
+ ::: "memory" : fault);
fault:
wrmsrl(MSR_EFER, efer & ~EFER_SVME);
}
diff --git a/arch/x86/kvm/svm/svm_ops.h b/arch/x86/kvm/svm/svm_ops.h
index 36c8af87a707..4e725854c63a 100644
--- a/arch/x86/kvm/svm/svm_ops.h
+++ b/arch/x86/kvm/svm/svm_ops.h
@@ -8,7 +8,7 @@
#define svm_asm(insn, clobber...) \
do { \
- asm_volatile_goto("1: " __stringify(insn) "\n\t" \
+ asm goto("1: " __stringify(insn) "\n\t" \
_ASM_EXTABLE(1b, %l[fault]) \
::: clobber : fault); \
return; \
@@ -18,7 +18,7 @@ fault: \
#define svm_asm1(insn, op1, clobber...) \
do { \
- asm_volatile_goto("1: " __stringify(insn) " %0\n\t" \
+ asm goto("1: " __stringify(insn) " %0\n\t" \
_ASM_EXTABLE(1b, %l[fault]) \
:: op1 : clobber : fault); \
return; \
@@ -28,7 +28,7 @@ fault: \
#define svm_asm2(insn, op1, op2, clobber...) \
do { \
- asm_volatile_goto("1: " __stringify(insn) " %1, %0\n\t" \
+ asm goto("1: " __stringify(insn) " %1, %0\n\t" \
_ASM_EXTABLE(1b, %l[fault]) \
:: op1, op2 : clobber : fault); \
return; \
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 98d732b9418f..57c1374fdfd4 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2469,10 +2469,10 @@ static int kvm_cpu_vmxon(u64 vmxon_pointer)
cr4_set_bits(X86_CR4_VMXE);
- asm_volatile_goto("1: vmxon %[vmxon_pointer]\n\t"
- _ASM_EXTABLE(1b, %l[fault])
- : : [vmxon_pointer] "m"(vmxon_pointer)
- : : fault);
+ asm goto("1: vmxon %[vmxon_pointer]\n\t"
+ _ASM_EXTABLE(1b, %l[fault])
+ : : [vmxon_pointer] "m"(vmxon_pointer)
+ : : fault);
return 0;
fault:
diff --git a/arch/x86/kvm/vmx/vmx_ops.h b/arch/x86/kvm/vmx/vmx_ops.h
index ec268df83ed6..5edab28dfb2e 100644
--- a/arch/x86/kvm/vmx/vmx_ops.h
+++ b/arch/x86/kvm/vmx/vmx_ops.h
@@ -73,7 +73,7 @@ static __always_inline unsigned long __vmcs_readl(unsigned long field)
#ifdef CONFIG_CC_HAS_ASM_GOTO_OUTPUT
- asm_volatile_goto("1: vmread %[field], %[output]\n\t"
+ asm_goto_output("1: vmread %[field], %[output]\n\t"
"jna %l[do_fail]\n\t"
_ASM_EXTABLE(1b, %l[do_exception])
@@ -166,7 +166,7 @@ static __always_inline unsigned long vmcs_readl(unsigned long field)
#define vmx_asm1(insn, op1, error_args...) \
do { \
- asm_volatile_goto("1: " __stringify(insn) " %0\n\t" \
+ asm goto("1: " __stringify(insn) " %0\n\t" \
".byte 0x2e\n\t" /* branch not taken hint */ \
"jna %l[error]\n\t" \
_ASM_EXTABLE(1b, %l[fault]) \
@@ -183,7 +183,7 @@ fault: \
#define vmx_asm2(insn, op1, op2, error_args...) \
do { \
- asm_volatile_goto("1: " __stringify(insn) " %1, %0\n\t" \
+ asm goto("1: " __stringify(insn) " %1, %0\n\t" \
".byte 0x2e\n\t" /* branch not taken hint */ \
"jna %l[error]\n\t" \
_ASM_EXTABLE(1b, %l[fault]) \
diff --git a/arch/xtensa/include/asm/jump_label.h b/arch/xtensa/include/asm/jump_label.h
index c812bf85021c..46c8596259d2 100644
--- a/arch/xtensa/include/asm/jump_label.h
+++ b/arch/xtensa/include/asm/jump_label.h
@@ -13,7 +13,7 @@
static __always_inline bool arch_static_branch(struct static_key *key,
bool branch)
{
- asm_volatile_goto("1:\n\t"
+ asm goto("1:\n\t"
"_nop\n\t"
".pushsection __jump_table, \"aw\"\n\t"
".word 1b, %l[l_yes], %c0\n\t"
@@ -38,7 +38,7 @@ static __always_inline bool arch_static_branch_jump(struct static_key *key,
* make it reachable and wrap both into a no-transform block
* to avoid any assembler interference with this.
*/
- asm_volatile_goto("1:\n\t"
+ asm goto("1:\n\t"
".begin no-transform\n\t"
"_j %l[l_yes]\n\t"
"2:\n\t"
diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
index f55a37efdb97..e31243ea637c 100644
--- a/include/linux/compiler-gcc.h
+++ b/include/linux/compiler-gcc.h
@@ -66,6 +66,25 @@
__builtin_unreachable(); \
} while (0)
+/*
+ * GCC 'asm goto' with outputs miscompiles certain code sequences:
+ *
+ * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110420
+ * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110422
+ *
+ * Work it around via the same compiler barrier quirk that we used
+ * to use for the old 'asm goto' workaround.
+ *
+ * Also, always mark such 'asm goto' statements as volatile: all
+ * asm goto statements are supposed to be volatile as per the
+ * documentation, but some versions of gcc didn't actually do
+ * that for asms with outputs:
+ *
+ * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98619
+ */
+#define asm_goto_output(x...) \
+ do { asm volatile goto(x); asm (""); } while (0)
+
#if defined(CONFIG_ARCH_USE_BUILTIN_BSWAP)
#define __HAVE_BUILTIN_BSWAP32__
#define __HAVE_BUILTIN_BSWAP64__
diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h
index eb0466236661..a95ec8a3a7ca 100644
--- a/include/linux/compiler_types.h
+++ b/include/linux/compiler_types.h
@@ -284,8 +284,8 @@ struct ftrace_likely_data {
# define __realloc_size(x, ...)
#endif
-#ifndef asm_volatile_goto
-#define asm_volatile_goto(x...) asm goto(x)
+#ifndef asm_goto_output
+#define asm_goto_output(x...) asm goto(x)
#endif
#ifdef CONFIG_CC_HAS_ASM_INLINE
diff --git a/net/netfilter/nft_set_pipapo_avx2.c b/net/netfilter/nft_set_pipapo_avx2.c
index 90e275bb3e5d..a3a8ddca9918 100644
--- a/net/netfilter/nft_set_pipapo_avx2.c
+++ b/net/netfilter/nft_set_pipapo_avx2.c
@@ -57,7 +57,7 @@
/* Jump to label if @reg is zero */
#define NFT_PIPAPO_AVX2_NOMATCH_GOTO(reg, label) \
- asm_volatile_goto("vptest %%ymm" #reg ", %%ymm" #reg ";" \
+ asm goto("vptest %%ymm" #reg ", %%ymm" #reg ";" \
"je %l[" #label "]" : : : : label)
/* Store 256 bits from YMM register into memory. Contrary to bucket load
diff --git a/samples/bpf/asm_goto_workaround.h b/samples/bpf/asm_goto_workaround.h
index 7048bb3594d6..634e81d83efd 100644
--- a/samples/bpf/asm_goto_workaround.h
+++ b/samples/bpf/asm_goto_workaround.h
@@ -4,14 +4,14 @@
#define __ASM_GOTO_WORKAROUND_H
/*
- * This will bring in asm_volatile_goto and asm_inline macro definitions
+ * This will bring in asm_goto_output and asm_inline macro definitions
* if enabled by compiler and config options.
*/
#include <linux/types.h>
-#ifdef asm_volatile_goto
-#undef asm_volatile_goto
-#define asm_volatile_goto(x...) asm volatile("invalid use of asm_volatile_goto")
+#ifdef asm_goto_output
+#undef asm_goto_output
+#define asm_goto_output(x...) asm volatile("invalid use of asm_goto_output")
#endif
/*
diff --git a/tools/arch/x86/include/asm/rmwcc.h b/tools/arch/x86/include/asm/rmwcc.h
index 11ff975242ca..e2ff22b379a4 100644
--- a/tools/arch/x86/include/asm/rmwcc.h
+++ b/tools/arch/x86/include/asm/rmwcc.h
@@ -4,7 +4,7 @@
#define __GEN_RMWcc(fullop, var, cc, ...) \
do { \
- asm_volatile_goto (fullop "; j" cc " %l[cc_label]" \
+ asm goto (fullop "; j" cc " %l[cc_label]" \
: : "m" (var), ## __VA_ARGS__ \
: "memory" : cc_label); \
return 0; \
diff --git a/tools/include/linux/compiler_types.h b/tools/include/linux/compiler_types.h
index 1bdd834bdd57..d09f9dc172a4 100644
--- a/tools/include/linux/compiler_types.h
+++ b/tools/include/linux/compiler_types.h
@@ -36,8 +36,8 @@
#include <linux/compiler-gcc.h>
#endif
-#ifndef asm_volatile_goto
-#define asm_volatile_goto(x...) asm goto(x)
+#ifndef asm_goto_output
+#define asm_goto_output(x...) asm goto(x)
#endif
#endif /* __LINUX_COMPILER_TYPES_H */
--
2.44.0.rc0.5.g95feb12ff0
[-- Attachment #3: 0002-update-workarounds-for-gcc-asm-goto-issue.patch --]
[-- Type: text/x-patch, Size: 4964 bytes --]
From 3a6d8ce9b40eef35295356c61c7b4d95481b9b45 Mon Sep 17 00:00:00 2001
From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Thu, 15 Feb 2024 11:14:33 -0800
Subject: [PATCH 2/2] update workarounds for gcc "asm goto" issue
[ Commit 68fb3ca0e408e00db1c3f8fccdfa19e274c033be upstream ]
In commit 4356e9f841f7 ("work around gcc bugs with 'asm goto' with
outputs") I did the gcc workaround unconditionally, because the cause of
the bad code generation wasn't entirely clear.
In the meantime, Jakub Jelinek debugged the issue, and has come up with
a fix in gcc [2], which also got backported to the still maintained
branches of gcc-11, gcc-12 and gcc-13.
Note that while the fix technically wasn't in the original gcc-14
branch, Jakub says:
"while it is true that no GCC 14 snapshots until today (or whenever the
fix will be committed) have the fix, for GCC trunk it is up to the
distros to use the latest snapshot if they use it at all and would
allow better testing of the kernel code without the workaround, so
that if there are other issues they won't be discovered years later.
Most userland code doesn't actually use asm goto with outputs..."
so we will consider gcc-14 to be fixed - if somebody is using gcc
snapshots of the gcc-14 before the fix, they should upgrade.
Note that while the bug goes back to gcc-11, in practice other gcc
changes seem to have effectively hidden it since gcc-12.1 as per a
bisect by Jakub. So even a gcc-14 snapshot without the fix likely
doesn't show actual problems.
Also, make the default 'asm_goto_output()' macro mark the asm as
volatile by hand, because of an unrelated gcc issue [1] where it doesn't
match the documented behavior ("asm goto is always volatile").
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103979 [1]
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113921 [2]
Link: https://lore.kernel.org/all/20240208220604.140859-1-seanjc@google.com/
Requested-by: Jakub Jelinek <jakub@redhat.com>
Cc: Uros Bizjak <ubizjak@gmail.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Andrew Pinski <quic_apinski@quicinc.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
include/linux/compiler-gcc.h | 7 ++++---
include/linux/compiler_types.h | 9 ++++++++-
init/Kconfig | 9 +++++++++
3 files changed, 21 insertions(+), 4 deletions(-)
diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
index e31243ea637c..149a520515e1 100644
--- a/include/linux/compiler-gcc.h
+++ b/include/linux/compiler-gcc.h
@@ -69,10 +69,9 @@
/*
* GCC 'asm goto' with outputs miscompiles certain code sequences:
*
- * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110420
- * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110422
+ * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113921
*
- * Work it around via the same compiler barrier quirk that we used
+ * Work around it via the same compiler barrier quirk that we used
* to use for the old 'asm goto' workaround.
*
* Also, always mark such 'asm goto' statements as volatile: all
@@ -82,8 +81,10 @@
*
* https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98619
*/
+#ifdef CONFIG_GCC_ASM_GOTO_OUTPUT_WORKAROUND
#define asm_goto_output(x...) \
do { asm volatile goto(x); asm (""); } while (0)
+#endif
#if defined(CONFIG_ARCH_USE_BUILTIN_BSWAP)
#define __HAVE_BUILTIN_BSWAP32__
diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h
index a95ec8a3a7ca..574b4121ebe3 100644
--- a/include/linux/compiler_types.h
+++ b/include/linux/compiler_types.h
@@ -284,8 +284,15 @@ struct ftrace_likely_data {
# define __realloc_size(x, ...)
#endif
+/*
+ * Some versions of gcc do not mark 'asm goto' volatile:
+ *
+ * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103979
+ *
+ * We do it here by hand, because it doesn't hurt.
+ */
#ifndef asm_goto_output
-#define asm_goto_output(x...) asm goto(x)
+#define asm_goto_output(x...) asm volatile goto(x)
#endif
#ifdef CONFIG_CC_HAS_ASM_INLINE
diff --git a/init/Kconfig b/init/Kconfig
index 148704640252..ffb927bf6034 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -89,6 +89,15 @@ config CC_HAS_ASM_GOTO_TIED_OUTPUT
# Detect buggy gcc and clang, fixed in gcc-11 clang-14.
def_bool $(success,echo 'int foo(int *x) { asm goto (".long (%l[bar]) - .": "+m"(*x) ::: bar); return *x; bar: return 0; }' | $CC -x c - -c -o /dev/null)
+config GCC_ASM_GOTO_OUTPUT_WORKAROUND
+ bool
+ depends on CC_IS_GCC && CC_HAS_ASM_GOTO_OUTPUT
+ # Fixed in GCC 14, 13.3, 12.4 and 11.5
+ # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113921
+ default y if GCC_VERSION < 110500
+ default y if GCC_VERSION >= 120000 && GCC_VERSION < 120400
+ default y if GCC_VERSION >= 130000 && GCC_VERSION < 130300
+
config TOOLS_SUPPORT_RELR
def_bool $(success,env "CC=$(CC)" "LD=$(LD)" "NM=$(NM)" "OBJCOPY=$(OBJCOPY)" $(srctree)/scripts/tools-support-relr.sh)
--
2.44.0.rc0.5.g95feb12ff0
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