lib/syscall_shim: Use global scope inline asm for execenv prologue

Avoid having to use weird and unconventional function attributes by
writing the inline assembly in a global scope. This is especially
useful for ARM64 as it does not support the naked attribute on GCC.

Signed-off-by: Sergiu Moga <sergiu@unikraft.io>
Approved-by: Andrei Tatar <andrei@unikraft.io>
Reviewed-by: Andrei Tatar <andrei@unikraft.io>
Reviewed-by: Michalis Pappas <michalis@unikraft.io>
GitHub-Closes: #1598

diff --git a/lib/syscall_shim/arch/arm64/include/arch/syscall_prologue.h b/lib/syscall_shim/arch/arm64/include/arch/syscall_prologue.h
index 2212d5f1f65ecdb00f36ab5629e991266462c59f..c04659bf124f873b09abc0b4ef1bb9e998ea834a 100644 (file)
--- a/lib/syscall_shim/arch/arm64/include/arch/syscall_prologue.h
+++ b/lib/syscall_shim/arch/arm64/include/arch/syscall_prologue.h
@@ -38,10 +38,11 @@
         (0b1101 << 6) /* D, A, I, F, only IRQ's unmasked */)
 
 #define UK_SYSCALL_EXECENV_PROLOGUE_DEFINE(pname, fname, x, ...)       \
-       long __used __noreturn __attribute__((optimize("O3")))          \
-       pname(UK_ARG_MAPx(x, UK_S_ARG_LONG_MAYBE_UNUSED, __VA_ARGS__))  \
-       {                                                               \
-               __asm__ __volatile__(                                   \
+       long __used                                                     \
+       pname(UK_ARG_MAPx(x, UK_S_ARG_LONG_MAYBE_UNUSED, __VA_ARGS__)); \
+       __asm__ (                                                       \
+               ".global " STRINGIFY(pname) "\n\t"                      \
+               "" STRINGIFY(pname) ":\n\t"                             \
                "/* No IRQ's during register saving please */\n\t"      \
                "msr    daifset, #2\n\t"                                \
                "/* Use TPIDRRO_EL0 as a scratch register. This\n\t"    \
@@ -137,8 +138,6 @@
                "ldr    x9, [sp, #" STRINGIFY(__SP_OFFSET) "]\n\t"      \
                "mov    sp, x9\n\t"                                     \
                "ret\n\t"                                               \
-               ::                                                      \
-               );                                                      \
-       }
+       );
 
 #endif /* !__ASSEMBLY__ */

diff --git a/lib/syscall_shim/arch/x86_64/include/arch/syscall_prologue.h b/lib/syscall_shim/arch/x86_64/include/arch/syscall_prologue.h
index 43a0737ae7838f1785b992d23bd9c93a4f3ab076..395fb66f26b5d9ee53fe5ff984dc45ad7f489c91 100644 (file)
--- a/lib/syscall_shim/arch/x86_64/include/arch/syscall_prologue.h
+++ b/lib/syscall_shim/arch/x86_64/include/arch/syscall_prologue.h
@@ -24,19 +24,20 @@
 #include <uk/essentials.h>
 
 #define UK_SYSCALL_EXECENV_PROLOGUE_DEFINE(pname, fname, x, ...)       \
-       long __used __naked __noreturn                                  \
-       pname(UK_ARG_MAPx(x, UK_S_ARG_LONG_MAYBE_UNUSED, __VA_ARGS__))  \
-       {                                                               \
-               __asm__ __volatile__(                                   \
+       long __used                                                     \
+       pname(UK_ARG_MAPx(x, UK_S_ARG_LONG_MAYBE_UNUSED, __VA_ARGS__)); \
+       __asm__ (                                                       \
+               ".global " STRINGIFY(pname) "\n\t"                      \
+               "" STRINGIFY(pname) ":\n\t"                             \
                "cli\n\t"                                               \
                "/* Switch to the per-CPU auxiliary stack */\n\t"       \
                "/* AMD64 SysV ABI: r11 is scratch register */\n\t"     \
-               "movq   %%rsp, %%r11\n\t"                               \
-               "movq   %%gs:(" STRINGIFY(LCPU_AUXSP_OFFSET) "), %%rsp\n\t"\
+               "movq   %rsp, %r11\n\t"                                 \
+               "movq   %gs:(" STRINGIFY(LCPU_AUXSP_OFFSET) "), %rsp\n\t"\
                "/* Auxiliary stack is already ECTX aligned */\n\t"     \
                "/* Make room for `struct UKARCH_EXECENV` */\n\t"       \
                "subq   $(" STRINGIFY(UKARCH_EXECENV_SIZE -             \
-                                    __REGS_SIZEOF)" ), %%rsp\n\t"      \
+                                    __REGS_SIZEOF)" ), %rsp\n\t"       \
                "/* Now build stack frame beginning with 5 pointers\n\t"\
                " * in the classical iretq/`struct __regs` format\n\t"  \
                " */\n\t"                                               \
@@ -47,7 +48,7 @@
                " */\n\t"                                               \
                "pushq  $(0x10)\n\t"                                    \
                "/* Push saving original rsp stored in r11 */\n\t"      \
-               "pushq  %%r11\n\t"                                      \
+               "pushq  %r11\n\t"                                       \
                "/* Push EFLAGS register. Additionally, since we\n\t"   \
                " * pushed it with IRQs disabled, it won't have\n\t"    \
                " * the corresponding bit flag set, making it look\n\t" \
@@ -56,63 +57,60 @@
                " * manually set the flag.\n\t"                         \
                " */\n\t"                                               \
                "pushfq\n\t"                                            \
-               "orq    $(" STRINGIFY(X86_EFLAGS_IF) "), 0(%%rsp)\n\t"  \
+               "orq    $(" STRINGIFY(X86_EFLAGS_IF) "), 0(%rsp)\n\t"   \
                "/* Push code segment, GDT code segment selector:\n\t"  \
                " * [15: 3]: Selector Index - first GDT entry\n\t"      \
                " * [ 2: 2]: Table Indicator - GDT, table 0\n\t"        \
                " * [ 1: 0]: Requestor Privilege Level - ring 0\n\t"    \
                " */\n\t"                                               \
                "pushq  $(0x8)\n\t"                                     \
-               "/* Save caller next rip, this part here\n\t"           \
-               " * is the reason why we depend on `__naked`, as we\n\t"\
-               " * rely on the aforementioned rip being placed at\n\t" \
+               "/* Save caller next rip, this part here.\n\t"          \
+               " * Rely on the aforementioned rip being placed at\n\t" \
                " * rsp + 8 initially w.r.t. `call` instruction.\n\t"   \
                " */\n\t"                                               \
-               "movq   (%%r11), %%r11\n\t"                             \
-               "pushq  %%r11\n\t"                                      \
+               "movq   (%r11), %r11\n\t"                               \
+               "pushq  %r11\n\t"                                       \
                "/* Now just push the rest of `struct __regs` */\n\t"   \
-               "pushq  %%rax\n\t"                                      \
-               "pushq  %%rdi\n\t"                                      \
-               "pushq  %%rsi\n\t"                                      \
-               "pushq  %%rdx\n\t"                                      \
-               "pushq  %%rcx\n\t"                                      \
-               "pushq  %%rax\n\t"                                      \
-               "pushq  %%r8\n\t"                                       \
-               "pushq  %%r9\n\t"                                       \
-               "pushq  %%r10\n\t"                                      \
-               "pushq  %%r11\n\t"                                      \
-               "pushq  %%rbx\n\t"                                      \
-               "pushq  %%rbp\n\t"                                      \
-               "pushq  %%r12\n\t"                                      \
-               "pushq  %%r13\n\t"                                      \
-               "pushq  %%r14\n\t"                                      \
-               "pushq  %%r15\n\t"                                      \
-               "subq   $(" STRINGIFY(__REGS_PAD_SIZE) "), %%rsp\n\t"   \
+               "pushq  %rax\n\t"                                       \
+               "pushq  %rdi\n\t"                                       \
+               "pushq  %rsi\n\t"                                       \
+               "pushq  %rdx\n\t"                                       \
+               "pushq  %rcx\n\t"                                       \
+               "pushq  %rax\n\t"                                       \
+               "pushq  %r8\n\t"                                        \
+               "pushq  %r9\n\t"                                        \
+               "pushq  %r10\n\t"                                       \
+               "pushq  %r11\n\t"                                       \
+               "pushq  %rbx\n\t"                                       \
+               "pushq  %rbp\n\t"                                       \
+               "pushq  %r12\n\t"                                       \
+               "pushq  %r13\n\t"                                       \
+               "pushq  %r14\n\t"                                       \
+               "pushq  %r15\n\t"                                       \
+               "subq   $(" STRINGIFY(__REGS_PAD_SIZE) "), %rsp\n\t"    \
                "/* ECTX at slot w.r.t. `struct UKARCH_EXECENV` */\n\t" \
-               "movq   %%rsp, %%rdi\n\t"                               \
+               "movq   %rsp, %rdi\n\t"                                 \
                "addq   $(" STRINGIFY(__REGS_SIZEOF +                   \
-                                    UKARCH_SYSCTX_SIZE) "), %%rdi\n\t" \
+                                    UKARCH_SYSCTX_SIZE) "), %rdi\n\t"  \
                "call   ukarch_ectx_store\n\t"                          \
                "/* SYSCTX at slot w.r.t. `struct UKARCH_EXECENV` */\n\t"\
-               "movq   %%rsp, %%rdi\n\t"                               \
-               "addq   $(" STRINGIFY(__REGS_SIZEOF) "), %%rdi\n\t"     \
+               "movq   %rsp, %rdi\n\t"                                 \
+               "addq   $(" STRINGIFY(__REGS_SIZEOF) "), %rdi\n\t"      \
                "call   ukarch_sysctx_store\n\t"                        \
-               "movq   %%rsp, %%rdi\n\t"                               \
+               "movq   %rsp, %rdi\n\t"                                 \
                "sti\n\t"                                               \
                "call   " STRINGIFY(fname) "\n\t"                       \
-               "addq   $(" STRINGIFY(__REGS_PAD_SIZE) "), %%rsp\n\t"   \
+               "addq   $(" STRINGIFY(__REGS_PAD_SIZE) "), %rsp\n\t"    \
                "/* Only restore callee preserved regs (ABI) */\n\t"    \
-               "popq   %%r15\n\t"                                      \
-               "popq   %%r14\n\t"                                      \
-               "popq   %%r13\n\t"                                      \
-               "popq   %%r12\n\t"                                      \
-               "popq   %%rbp\n\t"                                      \
-               "popq   %%rbx\n\t"                                      \
+               "popq   %r15\n\t"                                       \
+               "popq   %r14\n\t"                                       \
+               "popq   %r13\n\t"                                       \
+               "popq   %r12\n\t"                                       \
+               "popq   %rbp\n\t"                                       \
+               "popq   %rbx\n\t"                                       \
                "/* Restore rsp from where it was stored */\n\t"        \
-               "movq   104(%%rsp), %%rsp\n\t"                          \
+               "movq   104(%rsp), %rsp\n\t"                            \
                "ret\n\t"                                               \
-               ::                                                      \
-               );                                                      \
-       }
+       );
 
 #endif /* !__ASSEMBLY__ */