work around gcc bugs with 'asm goto' with outputs

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'.

but 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>

diff --git a/arch/arc/include/asm/jump_label.h b/arch/arc/include/asm/jump_label.h
index 9d96180797396bba26ace54f047f7a47bf82dd5f..a339223d9e052b35ea678d6a3e60faf6e5673671 100644 (file)
--- 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 @@ l_yes:
 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 e12d7d096fc034058bfaa094bf9b314a2a7a983d..e4eb54f6cd9fef41fecad56e25c4136e75455756 100644 (file)
--- 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 @@ l_yes:
 
 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 210bb43cff2c7d020fdf9dc1c8f2a99ca49415a0..d328f549b1a60a26bff884bccebe448fc0936f76 100644 (file)
--- a/arch/arm64/include/asm/alternative-macros.h
+++ b/arch/arm64/include/asm/alternative-macros.h
@@ -229,7 +229,7 @@ alternative_has_cap_likely(const unsigned long cpucap)
        if (!cpucap_is_possible(cpucap))
                return false;
 
-       asm_volatile_goto(
+       asm goto(
        ALTERNATIVE_CB("b       %l[l_no]", %[cpucap], alt_cb_patch_nops)
        :
        : [cpucap] "i" (cpucap)
@@ -247,7 +247,7 @@ alternative_has_cap_unlikely(const unsigned long cpucap)
        if (!cpucap_is_possible(cpucap))
                return false;
 
-       asm_volatile_goto(
+       asm goto(
        ALTERNATIVE("nop", "b   %l[l_yes]", %[cpucap])
        :
        : [cpucap] "i" (cpucap)

diff --git a/arch/arm64/include/asm/jump_label.h b/arch/arm64/include/asm/jump_label.h
index 48ddc0f45d2283f2c5ba0de62f5d3231999a91f3..6aafbb7899916e631eab9241c39c1313a7c93707 100644 (file)
--- 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 * const key,
                                               const 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 @@ l_yes:
 static __always_inline bool arch_static_branch_jump(struct static_key * const key,
                                                    const 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 98a3f4b168bd2687f3e4828aa681d29e0c13b97e..ef2e37a10a0feb9af3543481cffddd75c5b3a8ef 100644 (file)
--- 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 @@ label:
 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/loongarch/include/asm/jump_label.h b/arch/loongarch/include/asm/jump_label.h
index 3cea299a5ef58313a305f7d5a086ae9a32e8aa95..29acfe3de3faae797beca198e58f9e5a5e570bbc 100644 (file)
--- a/arch/loongarch/include/asm/jump_label.h
+++ b/arch/loongarch/include/asm/jump_label.h
@@ -22,7 +22,7 @@
 
 static __always_inline bool arch_static_branch(struct static_key * const key, const bool branch)
 {
-       asm_volatile_goto(
+       asm goto(
                "1:     nop                     \n\t"
                JUMP_TABLE_ENTRY
                :  :  "i"(&((char *)key)[branch]) :  : l_yes);
@@ -35,7 +35,7 @@ l_yes:
 
 static __always_inline bool arch_static_branch_jump(struct static_key * const key, const bool branch)
 {
-       asm_volatile_goto(
+       asm goto(
                "1:     b       %l[l_yes]       \n\t"
                JUMP_TABLE_ENTRY
                :  :  "i"(&((char *)key)[branch]) :  : l_yes);

diff --git a/arch/mips/include/asm/jump_label.h b/arch/mips/include/asm/jump_label.h
index 081be98c71ef48c698f4aa6ba14945239a666a9d..ff5d388502d4ab56ec28d71ad4126d542bb65977 100644 (file)
--- a/arch/mips/include/asm/jump_label.h
+++ b/arch/mips/include/asm/jump_label.h
@@ -39,7 +39,7 @@ extern void jump_label_apply_nops(struct module *mod);
 
 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"
@@ -53,7 +53,7 @@ l_yes:
 
 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 94428798b6aa63e8d4b0878cc7555826cf080e47..317ebc5edc9fe99950f4efe55d989db453f46d0d 100644 (file)
--- 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 @@ l_yes:
 
 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/jump_label.h b/arch/powerpc/include/asm/jump_label.h
index 93ce3ec253877d38da5e3f9c3ac76205354d3496..2f2a86ed2280aac66df0535d7938cf4a673446f7 100644 (file)
--- 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 @@ l_yes:
 
 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 f1f9890f50d3ef84dfd62b5d66db68315f0698b6..de10437fd20652ee63a6d214638bded13cdbc6c3 100644 (file)
--- a/arch/powerpc/include/asm/uaccess.h
+++ b/arch/powerpc/include/asm/uaccess.h
@@ -74,7 +74,7 @@ __pu_failed:                                                  \
 /* -mprefixed can generate offsets beyond range, fall back hack */
 #ifdef CONFIG_PPC_KERNEL_PREFIXED
 #define __put_user_asm_goto(x, addr, label, op)                        \
-       asm_volatile_goto(                                      \
+       asm goto(                                       \
                "1:     " op " %0,0(%1) # put_user\n"           \
                EX_TABLE(1b, %l2)                               \
                :                                               \
@@ -83,7 +83,7 @@ __pu_failed:                                                  \
                : label)
 #else
 #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)                               \
                :                                               \
@@ -97,7 +97,7 @@ __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)                               \
@@ -146,7 +146,7 @@ do {                                                                \
 /* -mprefixed can generate offsets beyond range, fall back hack */
 #ifdef CONFIG_PPC_KERNEL_PREFIXED
 #define __get_user_asm_goto(x, addr, label, op)                        \
-       asm_volatile_goto(                                      \
+       asm_goto_output(                                        \
                "1:     "op" %0,0(%1)   # get_user\n"           \
                EX_TABLE(1b, %l2)                               \
                : "=r" (x)                                      \
@@ -155,7 +155,7 @@ do {                                                                \
                : label)
 #else
 #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)                                      \
@@ -169,7 +169,7 @@ 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 938e66829eae65cc52d170f7753ee0685cdaa4e3..d5c48d1b0a31ea533281934e414320bbf77368d2 100644 (file)
--- a/arch/powerpc/kernel/irq_64.c
+++ b/arch/powerpc/kernel/irq_64.c
@@ -230,7 +230,7 @@ again:
         * 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/arch_hweight.h b/arch/riscv/include/asm/arch_hweight.h
index c20236a0725b9e27a31d28b580db1bd1ad2c945a..85b2c443823e8ab8ce55aa5b32953eabbc5e1108 100644 (file)
--- a/arch/riscv/include/asm/arch_hweight.h
+++ b/arch/riscv/include/asm/arch_hweight.h
@@ -20,7 +20,7 @@
 static __always_inline unsigned int __arch_hweight32(unsigned int w)
 {
 #ifdef CONFIG_RISCV_ISA_ZBB
-       asm_volatile_goto(ALTERNATIVE("j %l[legacy]", "nop", 0,
+       asm goto(ALTERNATIVE("j %l[legacy]", "nop", 0,
                                      RISCV_ISA_EXT_ZBB, 1)
                          : : : : legacy);
 
@@ -51,7 +51,7 @@ static inline unsigned int __arch_hweight8(unsigned int w)
 static __always_inline unsigned long __arch_hweight64(__u64 w)
 {
 # ifdef CONFIG_RISCV_ISA_ZBB
-       asm_volatile_goto(ALTERNATIVE("j %l[legacy]", "nop", 0,
+       asm goto(ALTERNATIVE("j %l[legacy]", "nop", 0,
                                      RISCV_ISA_EXT_ZBB, 1)
                          : : : : legacy);
 

diff --git a/arch/riscv/include/asm/bitops.h b/arch/riscv/include/asm/bitops.h
index 9ffc355370248aed22dbe690ba1cde8e682a3588..329d8244a9b3fd516104808db5a959acfb469b22 100644 (file)
--- a/arch/riscv/include/asm/bitops.h
+++ b/arch/riscv/include/asm/bitops.h
@@ -39,7 +39,7 @@ static __always_inline unsigned long variable__ffs(unsigned long word)
 {
        int num;
 
-       asm_volatile_goto(ALTERNATIVE("j %l[legacy]", "nop", 0,
+       asm goto(ALTERNATIVE("j %l[legacy]", "nop", 0,
                                      RISCV_ISA_EXT_ZBB, 1)
                          : : : : legacy);
 
@@ -95,7 +95,7 @@ static __always_inline unsigned long variable__fls(unsigned long word)
 {
        int num;
 
-       asm_volatile_goto(ALTERNATIVE("j %l[legacy]", "nop", 0,
+       asm goto(ALTERNATIVE("j %l[legacy]", "nop", 0,
                                      RISCV_ISA_EXT_ZBB, 1)
                          : : : : legacy);
 
@@ -154,7 +154,7 @@ static __always_inline int variable_ffs(int x)
        if (!x)
                return 0;
 
-       asm_volatile_goto(ALTERNATIVE("j %l[legacy]", "nop", 0,
+       asm goto(ALTERNATIVE("j %l[legacy]", "nop", 0,
                                      RISCV_ISA_EXT_ZBB, 1)
                          : : : : legacy);
 
@@ -209,7 +209,7 @@ static __always_inline int variable_fls(unsigned int x)
        if (!x)
                return 0;
 
-       asm_volatile_goto(ALTERNATIVE("j %l[legacy]", "nop", 0,
+       asm goto(ALTERNATIVE("j %l[legacy]", "nop", 0,
                                      RISCV_ISA_EXT_ZBB, 1)
                          : : : : legacy);
 

diff --git a/arch/riscv/include/asm/checksum.h b/arch/riscv/include/asm/checksum.h
index a5b60b54b101c3ba1e550b3e16e7096a6bfc8357..88e6f1499e889951b2871fec052330b3c92f2eb7 100644 (file)
--- a/arch/riscv/include/asm/checksum.h
+++ b/arch/riscv/include/asm/checksum.h
@@ -53,7 +53,7 @@ static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
            IS_ENABLED(CONFIG_RISCV_ALTERNATIVE)) {
                unsigned long fold_temp;
 
-               asm_volatile_goto(ALTERNATIVE("j %l[no_zbb]", "nop", 0,
+               asm goto(ALTERNATIVE("j %l[no_zbb]", "nop", 0,
                                              RISCV_ISA_EXT_ZBB, 1)
                    :
                    :

diff --git a/arch/riscv/include/asm/cpufeature.h b/arch/riscv/include/asm/cpufeature.h
index 5a626ed2c47a8915b3848df2e7f4a7ea0601bd71..0bd11862b7607b9ffebf8460ea6cc00cc1e4ff62 100644 (file)
--- a/arch/riscv/include/asm/cpufeature.h
+++ b/arch/riscv/include/asm/cpufeature.h
@@ -80,7 +80,7 @@ riscv_has_extension_likely(const unsigned long ext)
                           "ext must be < RISCV_ISA_EXT_MAX");
 
        if (IS_ENABLED(CONFIG_RISCV_ALTERNATIVE)) {
-               asm_volatile_goto(
+               asm goto(
                ALTERNATIVE("j  %l[l_no]", "nop", 0, %[ext], 1)
                :
                : [ext] "i" (ext)
@@ -103,7 +103,7 @@ riscv_has_extension_unlikely(const unsigned long ext)
                           "ext must be < RISCV_ISA_EXT_MAX");
 
        if (IS_ENABLED(CONFIG_RISCV_ALTERNATIVE)) {
-               asm_volatile_goto(
+               asm goto(
                ALTERNATIVE("nop", "j   %l[l_yes]", 0, %[ext], 1)
                :
                : [ext] "i" (ext)

diff --git a/arch/riscv/include/asm/jump_label.h b/arch/riscv/include/asm/jump_label.h
index 14a5ea8d8ef0f4a2f4477fb65778e4f8ea449e2a..4a35d787c0191475b3a5d8dc7452e448541dc8e9 100644 (file)
--- 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 @@ label:
 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/riscv/lib/csum.c b/arch/riscv/lib/csum.c
index af3df5274ccbae0118488080040f45881a3e025a..74af3ab520b6d433836930937dd90ffa2e672339 100644 (file)
--- a/arch/riscv/lib/csum.c
+++ b/arch/riscv/lib/csum.c
@@ -53,7 +53,7 @@ __sum16 csum_ipv6_magic(const struct in6_addr *saddr,
                 * support, so nop when Zbb is available and jump when Zbb is
                 * not available.
                 */
-               asm_volatile_goto(ALTERNATIVE("j %l[no_zbb]", "nop", 0,
+               asm goto(ALTERNATIVE("j %l[no_zbb]", "nop", 0,
                                              RISCV_ISA_EXT_ZBB, 1)
                                  :
                                  :
@@ -170,7 +170,7 @@ do_csum_with_alignment(const unsigned char *buff, int len)
                 * support, so nop when Zbb is available and jump when Zbb is
                 * not available.
                 */
-               asm_volatile_goto(ALTERNATIVE("j %l[no_zbb]", "nop", 0,
+               asm goto(ALTERNATIVE("j %l[no_zbb]", "nop", 0,
                                              RISCV_ISA_EXT_ZBB, 1)
                                  :
                                  :
@@ -178,7 +178,7 @@ do_csum_with_alignment(const unsigned char *buff, int len)
                                  : no_zbb);
 
 #ifdef CONFIG_32BIT
-               asm_volatile_goto(".option push                 \n\
+               asm_goto_output(".option push                   \n\
                .option arch,+zbb                               \n\
                        rori    %[fold_temp], %[csum], 16       \n\
                        andi    %[offset], %[offset], 1         \n\
@@ -193,7 +193,7 @@ do_csum_with_alignment(const unsigned char *buff, int len)
 
                return (unsigned short)csum;
 #else /* !CONFIG_32BIT */
-               asm_volatile_goto(".option push                 \n\
+               asm_goto_output(".option push                   \n\
                .option arch,+zbb                               \n\
                        rori    %[fold_temp], %[csum], 32       \n\
                        add     %[csum], %[fold_temp], %[csum]  \n\
@@ -257,7 +257,7 @@ do_csum_no_alignment(const unsigned char *buff, int len)
                 * support, so nop when Zbb is available and jump when Zbb is
                 * not available.
                 */
-               asm_volatile_goto(ALTERNATIVE("j %l[no_zbb]", "nop", 0,
+               asm goto(ALTERNATIVE("j %l[no_zbb]", "nop", 0,
                                              RISCV_ISA_EXT_ZBB, 1)
                                  :
                                  :

diff --git a/arch/s390/include/asm/jump_label.h b/arch/s390/include/asm/jump_label.h
index 895f774bbcc55353cc7a3d302b009796a799446f..bf78cf381dfcdac92a170b754328acd16846eb2e 100644 (file)
--- 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 @@ label:
 
 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 94eb529dcb77623caf637387e694d8e5ddc049a8..2718cbea826a7d13aefacd26fee3719b69856746 100644 (file)
--- 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 @@ l_yes:
 
 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 4b6d1b526bc1217e2e89d4670f9c4385e68dacc7..66fe06db872f05bb775f0089a4f134f77563efe4 100644 (file)
--- 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 a26bebbdff87ed20c45bdb98dcc4a8873f5c30f5..a1273698fc430b41951c241b6b76dfa9b7887692 100644 (file)
--- a/arch/x86/include/asm/cpufeature.h
+++ b/arch/x86/include/asm/cpufeature.h
@@ -168,7 +168,7 @@ 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 071572e23d3a06783e3a1f63e11bb47e99af9daa..cbbef32517f0049a3df51842162032ff1946e901 100644 (file)
--- 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 @@ l_yes:
 
 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 @@ l_yes:
 
 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 4b081e0d3306b79cca3dc222bb7406cde371d517..363266cbcadaf29e5bdeba4b0bfd5ab0ccb7355f 100644 (file)
--- a/arch/x86/include/asm/rmwcc.h
+++ b/arch/x86/include/asm/rmwcc.h
@@ -13,7 +13,7 @@
 #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/special_insns.h b/arch/x86/include/asm/special_insns.h
index d6cd9344f6c78e5555486e5d9f231fd27de9da6a..48f8dd47cf6882ac9e3920d6e7105c0eff430528 100644 (file)
--- a/arch/x86/include/asm/special_insns.h
+++ b/arch/x86/include/asm/special_insns.h
@@ -205,7 +205,7 @@ static inline void clwb(volatile void *__p)
 #ifdef CONFIG_X86_USER_SHADOW_STACK
 static inline int write_user_shstk_64(u64 __user *addr, u64 val)
 {
-       asm_volatile_goto("1: wrussq %[val], (%[addr])\n"
+       asm goto("1: wrussq %[val], (%[addr])\n"
                          _ASM_EXTABLE(1b, %l[fail])
                          :: [addr] "r" (addr), [val] "r" (val)
                          :: fail);

diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index 5c367c1290c355fb3849800a38c88c3553175903..237dc8cdd12b9482f38f8543b85dbde88fb98d65 100644 (file)
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -133,7 +133,7 @@ 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)                   \
@@ -295,7 +295,7 @@ 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)                                \
@@ -375,7 +375,7 @@ 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),                             \
@@ -394,7 +394,7 @@ 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),                             \
@@ -477,7 +477,7 @@ 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/kvm/svm/svm_ops.h b/arch/x86/kvm/svm/svm_ops.h
index 36c8af87a707ac0556fb1e50157e70c6305df798..4e725854c63a10c8645fa3b875a7a718020e96fe 100644 (file)
--- 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 e262bc2ba4e569983a94c3db5c13e1f0dabd9951..1111d9d089038b2f17b372891a235222b74f87bf 100644 (file)
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -738,7 +738,7 @@ static int vmx_set_guest_uret_msr(struct vcpu_vmx *vmx,
  */
 static int kvm_cpu_vmxoff(void)
 {
-       asm_volatile_goto("1: vmxoff\n\t"
+       asm goto("1: vmxoff\n\t"
                          _ASM_EXTABLE(1b, %l[fault])
                          ::: "cc", "memory" : fault);
 
@@ -2784,7 +2784,7 @@ static int kvm_cpu_vmxon(u64 vmxon_pointer)
 
        cr4_set_bits(X86_CR4_VMXE);
 
-       asm_volatile_goto("1: vmxon %[vmxon_pointer]\n\t"
+       asm goto("1: vmxon %[vmxon_pointer]\n\t"
                          _ASM_EXTABLE(1b, %l[fault])
                          : : [vmxon_pointer] "m"(vmxon_pointer)
                          : : fault);

diff --git a/arch/x86/kvm/vmx/vmx_ops.h b/arch/x86/kvm/vmx/vmx_ops.h
index f41ce3c24123a93e08a996d4daa8e033077caf6d..8060e5fc6dbd83e145f6c08fca370e4a42d9861b 100644 (file)
--- a/arch/x86/kvm/vmx/vmx_ops.h
+++ b/arch/x86/kvm/vmx/vmx_ops.h
@@ -94,7 +94,7 @@ 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])
@@ -188,7 +188,7 @@ 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])                   \
@@ -205,7 +205,7 @@ 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 c812bf85021c02db59d107fda752dba2872e3b60..46c8596259d2d921fc0395a9eaf8dd444032029c 100644 (file)
--- 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 aebb65bf95a7988dfe8cf9cb1b5ec0945640ced3..c1a963be7d289e6edafba98f1d7d0236ee4f69f1 100644 (file)
--- a/include/linux/compiler-gcc.h
+++ b/include/linux/compiler-gcc.h
@@ -64,6 +64,25 @@
                __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 6f1ca49306d2f7e7b51817fc579b82a85246736d..663d8791c871a7310467ea1b5417b65e58db604f 100644 (file)
--- a/include/linux/compiler_types.h
+++ b/include/linux/compiler_types.h
@@ -362,8 +362,8 @@ struct ftrace_likely_data {
 #define __member_size(p)       __builtin_object_size(p, 1)
 #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 90e275bb3e5d73f92fce8c6b66607229f2f62ed8..a3a8ddca991894b28aa1a1cd7c84ba0380366b5f 100644 (file)
--- 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 7048bb3594d65be6d132d4103ee801fadf087b7e..634e81d83efd9577337e37f1ce42911574b0adf9 100644 (file)
--- 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 11ff975242cac7cff4dfaab3a4591dc4cb82eb1d..e2ff22b379a44c584b7325249c48db9b3368c7d8 100644 (file)
--- 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 1bdd834bdd57198059c91222036314403191cdbc..d09f9dc172a486875e2e62cf8550a69f24c9beed 100644 (file)
--- 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 */