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| author | Peter Zijlstra <peterz@infradead.org> | 2021-11-10 11:01:09 +0100 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2021-12-11 09:09:46 +0100 |
| commit | 4b5305decc8436bfe363d1c1773e8fa1c828b14d (patch) | |
| tree | 44e15c683e80d0043af001e0dec2425575cc09b9 /arch/x86/include/asm/asm.h | |
| parent | aa93e2ad7464ffb90155a5ffdde963816f86d5dc (diff) | |
| download | linux-4b5305decc8436bfe363d1c1773e8fa1c828b14d.tar.gz linux-4b5305decc8436bfe363d1c1773e8fa1c828b14d.tar.bz2 linux-4b5305decc8436bfe363d1c1773e8fa1c828b14d.zip | |
x86/extable: Extend extable functionality
In order to remove further .fixup usage, extend the extable
infrastructure to take additional information from the extable entry
sites.
Specifically add _ASM_EXTABLE_TYPE_REG() and EX_TYPE_IMM_REG that
extend the existing _ASM_EXTABLE_TYPE() by taking an additional
register argument and encoding that and an s16 immediate into the
existing s32 type field. This limits the actual types to the first
byte, 255 seem plenty.
Also add a few flags into the type word, specifically CLEAR_AX and
CLEAR_DX which clear the return and extended return register.
Notes:
- due to the % in our register names it's hard to make it more
generally usable as arm64 did.
- the s16 is far larger than used in these patches, future extentions
can easily shrink this to get more bits.
- without the bitfield fix this will not compile, because: 0xFF > -1
and we can't even extract the TYPE field.
[nathanchance: Build fix for clang-lto builds:
https://lkml.kernel.org/r/20211210234953.3420108-1-nathan@kernel.org
]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://lore.kernel.org/r/20211110101325.303890153@infradead.org
Diffstat (limited to 'arch/x86/include/asm/asm.h')
| -rw-r--r-- | arch/x86/include/asm/asm.h | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/arch/x86/include/asm/asm.h b/arch/x86/include/asm/asm.h index 3a168483bc8e..c878fed3056f 100644 --- a/arch/x86/include/asm/asm.h +++ b/arch/x86/include/asm/asm.h @@ -152,6 +152,33 @@ #else /* ! __ASSEMBLY__ */ +# define DEFINE_EXTABLE_TYPE_REG \ + ".macro extable_type_reg type:req reg:req\n" \ + ".set found, 0\n" \ + ".set regnr, 0\n" \ + ".irp rs,rax,rcx,rdx,rbx,rsp,rbp,rsi,rdi,r8,r9,r10,r11,r12,r13,r14,r15\n" \ + ".ifc \\reg, %%\\rs\n" \ + ".set found, found+1\n" \ + ".long \\type + (regnr << 8)\n" \ + ".endif\n" \ + ".set regnr, regnr+1\n" \ + ".endr\n" \ + ".set regnr, 0\n" \ + ".irp rs,eax,ecx,edx,ebx,esp,ebp,esi,edi,r8d,r9d,r10d,r11d,r12d,r13d,r14d,r15d\n" \ + ".ifc \\reg, %%\\rs\n" \ + ".set found, found+1\n" \ + ".long \\type + (regnr << 8)\n" \ + ".endif\n" \ + ".set regnr, regnr+1\n" \ + ".endr\n" \ + ".if (found != 1)\n" \ + ".error \"extable_type_reg: bad register argument\"\n" \ + ".endif\n" \ + ".endm\n" + +# define UNDEFINE_EXTABLE_TYPE_REG \ + ".purgem extable_type_reg\n" + # define _ASM_EXTABLE_TYPE(from, to, type) \ " .pushsection \"__ex_table\",\"a\"\n" \ " .balign 4\n" \ @@ -160,6 +187,16 @@ " .long " __stringify(type) " \n" \ " .popsection\n" +# define _ASM_EXTABLE_TYPE_REG(from, to, type, reg) \ + " .pushsection \"__ex_table\",\"a\"\n" \ + " .balign 4\n" \ + " .long (" #from ") - .\n" \ + " .long (" #to ") - .\n" \ + DEFINE_EXTABLE_TYPE_REG \ + "extable_type_reg reg=" __stringify(reg) ", type=" __stringify(type) " \n"\ + UNDEFINE_EXTABLE_TYPE_REG \ + " .popsection\n" + /* For C file, we already have NOKPROBE_SYMBOL macro */ /* |