From: Matthieu Longo Date: Thu, 21 Nov 2024 18:44:07 +0000 (+0000) Subject: aarch64: make explicit that CFI gnu_window_save is for Sparc, not AArch64 X-Git-Tag: binutils-2_44~151 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=b4c230fe2283cfe1a14426f68a1b76b05596a295;p=thirdparty%2Fbinutils-gdb.git aarch64: make explicit that CFI gnu_window_save is for Sparc, not AArch64 - add a detailed comment when parsing DW_CFA_GNU_window_save in SFrame to explain why we are checking whether the targeted architecture is AArch64, whereas this CFI is a Sparc extension. - replace .cfi_gnu_window_save by .cfi_negate_ra_state in existing AArch64 DWARF tests as this is the preferred directive since GCC 15. - add a new AArch64 test to check backward compatibility with old GCC versions that emits .cfi_gnu_window_save. Approved-by: Indu Bhagat Approved-by: Richard Earnshaw --- diff --git a/gas/gen-sframe.c b/gas/gen-sframe.c index 71296f2f4fb..960c22e05f5 100644 --- a/gas/gen-sframe.c +++ b/gas/gen-sframe.c @@ -1273,7 +1273,13 @@ sframe_xlate_do_aarch64_negate_ra_state (struct sframe_xlate_ctx *xlate_ctx, } /* Translate DW_CFA_GNU_window_save into SFrame context. - DW_CFA_AARCH64_negate_ra_state is multiplexed with DW_CFA_GNU_window_save. + DW_CFA_GNU_window_save is a DWARF Sparc extension, but is multiplexed with a + directive of DWARF AArch64 extension: DW_CFA_AARCH64_negate_ra_state. + The AArch64 backend of GCC 14 and older versions was emitting mistakenly the + Sparc CFI directive (.cfi_window_save). From GCC 15, the AArch64 backend + only emits .cfi_negate_ra_state. For backward compatibility, the handler for + .cfi_window_save needs to check whether the directive was used in a AArch64 + ABI context or not. Return SFRAME_XLATE_OK if success. */ static int diff --git a/gas/testsuite/gas/aarch64/pac_ab_key.s b/gas/testsuite/gas/aarch64/pac_ab_key.s index 4b328e72ae4..3b81919409d 100644 --- a/gas/testsuite/gas/aarch64/pac_ab_key.s +++ b/gas/testsuite/gas/aarch64/pac_ab_key.s @@ -7,7 +7,7 @@ _Z5foo_av: .LFB0: .cfi_startproc hint 25 // paciasp - .cfi_window_save + .cfi_negate_ra_state stp x29, x30, [sp, -16]! .cfi_def_cfa_offset 16 .cfi_offset 29, -16 @@ -23,7 +23,7 @@ _Z5foo_bv: .cfi_startproc .cfi_b_key_frame hint 27 // pacibsp - .cfi_window_save + .cfi_negate_ra_state stp x29, x30, [sp, -16]! .cfi_def_cfa_offset 16 .cfi_offset 29, -16 diff --git a/gas/testsuite/gas/aarch64/pac_compat_cfi_window_save.d b/gas/testsuite/gas/aarch64/pac_compat_cfi_window_save.d new file mode 100644 index 00000000000..8e59086c1b4 --- /dev/null +++ b/gas/testsuite/gas/aarch64/pac_compat_cfi_window_save.d @@ -0,0 +1,44 @@ +#objdump: --dwarf=frames +# This test is only valid on ELF based ports. +#notarget: *-*-*coff *-*-pe *-*-wince *-*-*aout* *-*-netbsd + +## ARMv8.3 adds support for a new security feature named Pointer Authentication. +## The main idea behind this is to use the unused bits in the pointer values. +## Each pointer is patched with a PAC before writing to memory, and is verified +## before using it. +## When the pointers are mangled, the stack trace generator needs to know so it +## can mask off the PAC from the pointer value to recover the return address, +## and conversely, skip doing so if the pointers are not mangled. +## +## .cfi_negate_ra_state CFI directive is usually used to convey this information. +## .cfi_negate_ra_state and .cfi_window_save are both in the processor-specific +## numbering space, but use the same code value in the dwarf tables. +## In GCC 14 and older, the Sparc DWARF extension .cfi_window_save is emitted +## instead of .cfi_negate_ra_state, but it mapped to the same value. GCC 15 fixed +## this naming issue and there is no change to the object file created when the +## source is assembled. Nevertheless the support for the SPARC directive is +## preserved in binutils for backward compatibility with existing GCC releases, +## hence this test. + +.+: file .+ + +Contents of the .eh_frame section: + +0+ 0+10 0+ CIE + Version: 1 + Augmentation: "zR" + Code alignment factor: 4 + Data alignment factor: -8 + Return address column: 30 + Augmentation data: 1b + DW_CFA_def_cfa: r31 \(sp\) ofs 0 + +0+14 0+18 0+18 FDE cie=0+ pc=0+\.\.0+8 + DW_CFA_advance_loc: 4 to 0+4 + DW_CFA_AARCH64_negate_ra_state + DW_CFA_advance_loc: 4 to 0+8 + DW_CFA_def_cfa_offset: 16 + DW_CFA_offset: r29 \(x29\) at cfa-16 + DW_CFA_offset: r30 \(x30\) at cfa-8 + DW_CFA_nop + DW_CFA_nop diff --git a/gas/testsuite/gas/aarch64/pac_compat_cfi_window_save.s b/gas/testsuite/gas/aarch64/pac_compat_cfi_window_save.s new file mode 100644 index 00000000000..92a54f3a344 --- /dev/null +++ b/gas/testsuite/gas/aarch64/pac_compat_cfi_window_save.s @@ -0,0 +1,20 @@ + .arch armv8-a + .text + .align 2 + .global _Z5foo_av + .type _Z5foo_av, %function +_Z5foo_av: +.LFB0: + .cfi_startproc + hint 25 // paciasp + .cfi_window_save // really .cfi_negate_ra_state + stp x29, x30, [sp, -16]! + .cfi_def_cfa_offset 16 + .cfi_offset 29, -16 + .cfi_offset 30, -8 + .cfi_endproc +.LFE0: + .size _Z5foo_av, .-_Z5foo_av + .align 2 + .global _Z5foo_bv + .type _Z5foo_bv, %function